Tag Archives: snake

Highly venomous sea snakes may be attacking scuba divers as a mating behavior

Credit: Jack Breedon.

There has been a worrisome amount of documented attacks by venomous Olive sea snakes on scuba divers over the years. This has always struck marine biologists as very odd seeing how the vast majority of these encounters were unprovoked. A new study may finally explain what’s going on -and it’s not getting any less weird. Apparently, the snakes may be confusing the divers with potential mates, accidentally biting them as part of their courtship behavior.

According to an analysis of Olive sea snake encounters, researchers in Australia found that the vast majority of attacks were performed by males during the mating season, between May and August.

To some snakes, humans may look just like oversized females

A curious Olive sea snake approaching a diver. Credit: Claire Goiran.

Richard Shine, professor of biology at Macquarie University in Australia and corresponding author of the new study, knows firsthand about the bizarre behavior of Olive sea snakes (Aipysurus laevis). Between 1994 and 1995, Lynch had 158 encounters with these sea snakes, 74 of which resulted in approaches, while diving in the Great Barrier Reef. It was data on these encounters that Lynch and colleagues analyzed in order to spot any meaningful patterns that may explain some of these dangerous unprovoked attacks.

In general, although they’re greatly feared by humans, terrestrial snakes would much rather escape than confront an approaching person. Why would sea snakes be any different? What’s more, why would a snake approach and bite a human that has not harassed it, is obviously too large to constitute prey, and could easily be evaded by maneuvering around the coral? The researchers set out to answer these questions.

Looking closely at the encounter data, the researchers noticed that 39 of 58 approaches involved males while 35 of 100 were males. Outside the breeding season, males were rarely observed approaching divers, whereas the proportion of females approaching divers did not differ significantly between breeding and non-breeding seasons.

Another notable difference was that males were also more likely to tongue-flick divers. In 13 encounters, all during the breeding season, the sea snakes rapidly charged at divers aggressively. Charges involving males occurred immediately after an unsuccessful chase of a female or interaction with another rival male. In the rare instances that females charged a diver, they did so after they were chased by males and encountered the diver in their vicinity.

Three males were particularly odd, coiling around the diver’s fin, a behavior typically seen during courtship. Luckily, no bites were recorded during these interactions although the snakes struck at their reflections in camera lenses.

“However, snakes readily tried to bite when harassed during capture, or (especially) when handled on the boat after capture. Male snakes can be highly persistent in their attempts to approach divers. On one occasion the diver attempted to flee from a snake by swimming vigorously for 20 min but was unable to outpace his follower. When the diver finally stopped, the snake tongue-flicked him for a minute and then left,” the researchers wrote in the journal Scientific Reports.

Terrestrial snakes, the sister group to hydrophiinae like Olive sea snakes, rely on pheromones to locate and recognize females. However, such chemicals are not water-soluble and hence, cannot be detected from a distance in marine environments. And although Olive sea snakes have better visual acuity than some other species in their group, their eyesight is not nearly as good as their terrestrial cousins. They likely see quite poorly underwater.

Taken together, these observations seem to point to the idea that male Olive sea snakes mistake human divers for other male rivals or potential mates. This wouldn’t be the first time since this behavior is almost identical to that of males of the Turtle-headed sea snake (Emydocephalus annulatus).

However, the potential consequences are very different. While the Turtle-headed sea snake is small and non-toxic, the Olive sea snake is large and possesses a deadly venom, which is why the researchers ended their study on a cautionary note.

“If mistaken identity underlies most “attacks” by sea snakes on divers, the best strategy for divers in such a situation may be to allow the snake to investigate them and in particular to allow for the snake to investigate chemical cues with its tongue; a bite is unlikely unless the animal is threatened or injured. Attempting to flee is likely to be futile and may even increase the ardour of the pursuit; and attempting to drive the animal away may induce retaliation,” the researchers advised. 

Scientists zoom in on snake skin to see how they navigate sandy surfaces

Despite having a similar body shape and structure, not all snakes move in the same way. Most, when they move from A to B, slither head-first. But a minority of them (especially desert snakes) do it differently: they slither with their mid-sections first, slithering sideways across the loose sand. Now, researchers know why.

At first glance, you’d think that snakes have a hard time moving around — after all, they have no legs. But here’s the thing: not only do snakes do just fine by slithering, they’re found in almost all environments on Earth, managing to thrive on a variety of surfaces, including sandy environments.

If you’ve ever tried jogging on a beach, you know how hard moving across loose sand is. Now imagine you’re a snake, and your whole body is essentially a sole, how would you even manage moving around?

Researchers have known for a while that snakes in sandy environments tend to move in a different way than others, and they suspected it has something to do with the sand itself. So they set out to investigate it.

“The specialized locomotion of sidewinders evolved independently in different species in different parts of the world, suggesting that sidewinding is a good solution to a problem,” says Jennifer Rieser, assistant professor of physics at Emory University and a first author of the study. “Understanding how and why this example of convergent evolution works may allow us to adapt it for our own needs, such as building robots that can move in challenging environments.”

Rieser’s work joins together biology and soft matter physics (flowable materials, like sand). She studies how animals move around on these surfaces, and how this could help us develop new technologies by adapting what we see in nature (something called biomimicry).

Snakes are particularly interesting because they move in such a peculiar way. Even though snakes “have a relatively simple body plan, they are able to navigate a variety of habitats successfully,” she says. What we’ve learned from snakes has already been applied in several fields. Their long flexible bodies have inspired robots used in surgical procedures or search missions in collapsed buildings, for instance.

The key to the movements of these sidewinder snakes lies in their bellies — in the tiny details of their bellies, to be precise. Rieser and colleagues analyzed three sidewinder snakes (all vipers). They gathered skin the snakes had shed and looked at it with an atomic microscope, zooming in to the atomic level. They also scanned skins shed by non-sidewinders for comparison.

A zoomed-in comparison between holes on a sidewinder snake skin (left) and a non-sidewinder snake skin (right). A mathematical model developed by the researchers shows that the lack of spikes allows sidewinder snakes to move on loose surfaces. Image credits: Tai-De Li.

The regular, non-sidewinder snakes had tiny spikes on their skin, invisible to the human eye. These spikes create friction between the snake and the surface, which acts as a grip allowing them to propel themselves forward headfirst. The sidewinders, however, didn’t have the spikes. Instead, they had tiny holes, because you can’t really create friction or a grip with a surface like sand (that’s also why it’s harder to run on sand than concrete or soil).

“You can think about it like the ridges on corduroy material,” Rieser says. “When you run your fingers along corduroy in the same direction as the ridges there is less friction than when you slide your fingers across the ridges.”

However, some snakes also seemed to have a few spikes, which researchers interpret as a sort of evolutionary “work in progress”. These snakes are younger in their evolutionary history, and haven’t yet had time to fully shed their spikes, the team explains.

“That may explain why the sidewinder rattlesnake still has a few micro spikes left on its belly,” Rieser says. “It has not had as much time to evolve specialized locomotion for a sandy environment as the two African species, that have already lost all of their spikes.”

As for biomimicry, it’s a good lesson: if you want to build a robot that can move on a sand or sand-like surface, you need to pay attention to the texture of its skin.

Journal Reference: Jennifer M. Rieser el al., “Functional consequences of convergently evolved microscopic skin features on snake locomotion,” PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2018264118

This snake turns into a ‘lasso’ to climb trees

You’d think that a limbless creature would be a poor climber. But what they may lack in hands, digits, and claws, invasive brown tree snakes in Guam more than compensate for with creativity and technique. In a new study, shocked researchers document a new mode of snake locomotion, a lasso-like movement for climbing up smooth vertical cylinders. The flabbergasting account may have important implications for the conservation of the few remaining birds native to Guam.

“Martin Kastner, a CSU biologist, and I had watched about four hours of video [see below] and then all of a sudden, we saw this snake form what looked like a lasso around the cylinder and wiggle its body up. We watched that part of the video about 15 times. It was a shocker. Nothing I’d ever seen compares to it,” Thomas Seibert, a researcher at Colorado State University (CSU) and co-author of the new study, said in a statement.

Snakes move about using four modes of locomotion, known as rectilinear, lateral undulation, sidewinding, and concertina modes. The newly identified lasso-like locomotion is thus the fifth mode of locomotion seen in a snake species in over a hundred years — and it was discovered completely by accident.

In the 1940s, brown tree snakes (Boiga irregularis) were introduced by humans to Guam. Not long after, native bird populations were decimated. Today, only two native species remain, Micronesian starlings and another cave-nesting bird, both found in very small numbers.

Julie Savidge of Colorado State University was working on a conservation project designed to protect the nests of Micronesia starlings, which also involved implementing barriers against tree snakes. To keep the snakes out of bird boxes, the researchers used a three-foot-long metal baffle, which was previously used to keep raccoons away from nest boxes in the yards of birdwatchers. This worked well enough — until it didn’t.

Savidge and her colleagues were baffled when they saw persistent brown tree snakes latch onto the baffle’s cylinder by coiling around it, before proceeding to climb the cylinder.

When climbing trees, snakes typically employ a concertina motion, bending sideways to grip smooth branches in two places. The lasso locomotion is different, though. By forming a “lasso”, the snakes make contact with a single gripping region. The snakes then advance vertically by slowly shifting the location of little bends within the loop of the lasso.

All of this motion, however, is very technical, challenging, and highly taxing for the snakes, which often slip, stop to rest, and breathe heavily.

“Even though they can climb using this mode, it is pushing them to the limits,” said co-senior author Bruce Jayne of the University of Cincinnati.

Understanding how tree snakes find their way around barriers is critical to bird conservation in Guam and elsewhere in the world. The researchers are now designing a baffle that brown tree snakes can’t traverse.

The findings appeared in the journal Current Biology.

Fossil Friday: oldest python ever found suggests they’re originally from Europe

New research on fossilized snake remains unearthed in Germany points to our favorite constrictor snake having evolved in Europe. Today, the Pythonidae family is found mainly in Africa, Southern and Southeast Asia, and Australia.

Photographs and drawings of Messelopython freyi. Image credits Hussam Zaher and Krister T. Smith, (2020),  Biology Letters.

Don’t judge a book by its cover, nor a species by its current range, it turns out. New research suggests the python family first evolved on the European peninsula at least 47 million years ago, going a long way towards uncovering the group’s evolutionary past.

Das Python

“The geographic origin of pythons is still not clear. The discovery of a new python species in the Messel Pit is therefore a major leap forward in understanding these snakes’ evolutionary history,” explains Dr. Krister Smith of the Senckenberg Research Institute and Natural History Museum in Frankfurt, a co-author of the paper describing the new specimen.

The new species — christened Messelopython freyi in honor of Eberhard Frey, a paleontologist and chief curator of the State Museum of Natural History in Karlsruhe — was discovered at the Messel Pit UNESCO World Heritage Site in Germany, as a series of superbly-preserved specimens. They’re around 47 million years old and, reaching up to 6 meters in length, they’re among the largest snakes ever found.

It’s also the oldest species of python ever found. The team says these specimens show that pythons were already present in Europe during the Eocene, and that they likely evolved here to begin with.

But, locals may know, there are no pythons endemic to the European peninsula right now — which means that this group eventually spread from here before going extinct in the region, or migrated away entirely. The team explains that a drop in global temperatures during the Miocene (between 23 and 5 million years ago) made Europe too cold for pythons, who disappeared from the peninsula around this time.

However, there was another interesting tidbit to the findings. Today’s boas and pythons, although being very similar anatomically and closely related, live in complete geographical separation — they inhabit different ranges. This wasn’t the case in primeval Europe.

“In Messel, both Messelopython freyi as well as primitive boas such as Eoconstrictor fischeri lived together in the same ecosystem – we therefore have to revisit the thesis that these two groups of snakes competed with each other, making them unable to share the same habitats,” explains Smith.

The paper “Pythons in the Eocene of Europe reveal a much older divergence of the group in sympatry with boas” has been published in the journal Biology Letters.

Why researchers want to keep ratsnakes out of electrical lines

Eastern ratsnake slithering down a tree at Shenandoah River State Park. Credit: Virginia State Parks.

On June 26, 2020, Kevin Hamed of Blacksburg, Virginia, while out enjoying a summer day, spotted a snake on the road in the vicinity of Virginia Tech’s Kentland Farm. As he waited for the vehicle in front of him to pass by, Hamed was certain he would catch the snake and add it to his collection at Virginia Tech.

What Hamed did not expect was for that vehicle to swerve as if to hit the snake on purpose. The snake turned out to be a completely harmless Eastern ratsnake (Pantherophis alleghaniensis). Hamed reports that for each ratsnake he happens to catch in rural Montgomery County, there are two more that are killed.

Unfortunately, the vehicle Hamed witnessed, backed up and ran over the snake two more times, and then one final time. Hamed admits this is common, but it is actually illegal under Virginia law.

According to Hamed, who is part of the Virginia Herpetological Society and a Virginia Tech wildlife conservation professor, “you hear it a lot: the only good snake is a dead snake.” What people might not realize is that snakes are an important component of ecosystems, as well as playing a role in the economy.

One of the reasons Hamed and his associates have been collecting snakes all summer is to closely observe their climbing behaviors. The study, sponsored by TE Connectivity, a business making electrical utility components, has allocated $8,400 to help Hamed develop devices that help keep these Eastern ratsnakes from making their way into electrical lines and transformers.

Power outages that occur as a result of wildlife cost utility companies upwards of $10 billion each and every year, according to statistics from TE Connectivity. Birds can be blamed for about 50 percent of these outages, but Lori Lyons, company spokesperson, reports that snakes are not far behind.

The reason for this is that snakes regularly prey on the birds that nest in electrical equipment and on poles. They are well known for their climbing ability and they are able to make their way up these poles to prey on birds and raid the nests for eggs. Most of the time the snake dies in the process, while also short-circuiting the equipment, simultaneously being electrocuted and knocking out the power in many homes and businesses.

Each of these outages can cost $10,000 to repair and can result in fines for companies that are not doing enough to protect the local wildlife. Preventing this damage has become a top priority for many utility companies.

According to Hamed, it is vital to protect the ratsnakes for conservation reasons because the snakes help control the rodent population, thereby helping to prevent damage to local crops and controlling the spread of tick-borne diseases.

“Farmers will automatically tell you their value,” Hamed told Roanoke Times. “They are consuming things that most people would consider pests. They’re consuming rodents and small mammals,” he adds.

Mice and chipmunks are carriers of ticks that cause disease so controlling their numbers is beneficial for the entire community. Hamed reports that studies have found that low snake populations often coincide with high rates of Lyme disease, which is a bacterial infection that attacks the nervous system and is caused by ticks.

Another benefit that ratsnakes provide is their diet of invasive bird species, including starlings and house sparrows, both of which came from Europe and can displace species that are native to the area. Snakes also provide a food source for owls, eagles, and hawks.

These snakes are not a threat to humans, even if they are in a person’s house. They are able to bite, but don’t have fangs and are not venomous. According to Hamed, they also strike slowly, giving you time to dodge a bite, should it occur. “They’re the Labrador Retriever of the snake world,” he says.


Recently, a three-foot ratsnake was given to Hamed by Aidan McCarthy and was subsequently placed on a utility pole. The snake remained calm, both in Aidan’s hands and on the pole and its tail had to be touched to elicit movement. The snake slithered its way to the top of the pole twice, taking a different route each time. Sam Van Noy, senior wildlife conservation student, filmed the snake’s movements for later study.

The snake, called Ratsnake 19, is one of 24 ones being used in the study, says Hamed. Filming will continue for three days and then the snakes are returned to the location in which they were caught. Both McCarthy and Van Noy say they have felt a kinship with snakes since they were children.

Van Noy says he spent much of his childhood in the woods “flipping over rocks to see what was under them.” McCarthy, who grew up in Fairfax, says it was not so easy for him. “I would see them on TV, and go out and try to find them,” he reports. Since he made the move to Blacksburg, he says “they’re a lot easier to find.”

There is very little common ground when it comes to snakes. Hamed reports that surveys on the subject find that people either love snakes or they hate snakes. He is hoping that the work of his study helps educate others about ratsnakes and how important it is to protect them.

According to Hamed, “snakes are critical components of the ecosystem. Often that’s a hard sell for people who might have a fear of snakes.” He goes on to say, “yeah, a snake gets on your deck occasionally and scares you, but it’s beneficial to you.”

In addition, Hamed says that keeping ratsnakes away from power source ensures the power stays on.

Snakes aren’t always cold and unfriendly — garter snakes can form surprising relationships

Garter snakes not only prefer to hang out more with some individuals — they even have “friends”.

Not much is known about the social life of snakes. They’re secretive creatures, difficult to study, and research on the social habits of animals have typically focused on other types of animals — it’s a persistent scientific bias, the authors of a new study write.

“This bias is exacerbated by the fact that in some reptile species, social interactions are hidden, due to their secretive nature, and that social communication is often conducted via invisible chemical cue,” the study writes.

Thankfully, more studies are being carried on “unpopular” creatures recently, and that includes snakes.

In a recent such study, comparative psychologist Noam Miller and his graduate student Morgan Skinner at Wilfrid Laurier University, Canada, have started sociality studies on a wide range of species — including eastern garter snakes (Thamnophis sirtalis sirtalis).

The duo worked to assess the snakes’ personalities and social preferences. They placed sets of 10 snakes, each with a colored dot on its head, in a walled enclosure, observing their behavior with a camera. Twice a day, the reptiles were removed and their enclosure was cleaned to erase any odors, and the snakes were placed back in random positions. Regardless of how the snakes were placed, the same social structures were formed after a while — time and time again.

The researchers also tested each snake’s personality by placing them alone in a shelter and monitoring how much time snakes would spend outside the shelter. Some were bolder and went out of the shelter for longer periods of time, where others were shyer and stuck to the shelter. This is a significant personality trait of snakes, and researchers found it to be a major driver of friendship groups among the snakes. Snakes were also more likely to remain in a shelter that housed multiple snakes, suggesting that they find some safety in numbers.

Garter snakes might not always aggregate together, but when they do (such as in this study when researchers essentially forced a group of them to stay together), they form cliques and groups that bear a striking resemblance to that of mammals — you might even call them friendship groups.

“We demonstrate that the snakes actively seek social interaction, prefer to remain with larger aggregates, and associate non-randomly with specific individuals or groups. We show that their social interaction patterns are influenced by individual boldness, sociability, and age,” the team writes.

There are benefits to being social, especially when it comes to younger or more vulnerable snakes. A group retains heat and moisture better than an individual, and a group also has a better chance of defending against predators.

The study is significant in two ways. For starters, it contributes to a sparse (but growing) body of literature on sociability in reptiles. Secondly, it can work to change the perception among both the scientific community and the public, which can help conservation efforts.

Snakes had hind legs for 70 million years

Snakes have been around for at least 170 million years, since the upper Middle Jurassic Period, but scientists know surprisingly little about their evolution due to a sparse fossil record. What’s certain is that they once had hind legs and only later became limbless. A new study suggests that this transition took place over a much larger period of time than previously thought.

Render of Najash by Raúl O. Gómez, Universidad de Buenos Aires, Buenos Aires, Argentina.

An international team of researchers recently described an ancient snake with hind limbs, known as Najash rionegrina (in the bible, Nahash is a legged snake, which is Hebrew for snake).

The first description of Najash, which was first discovered 13 years ago, was based on a fragmented skull. This led to a lot of guesswork concerning the primitive snake’s appearance. What was clear even from this incomplete specimen is that Najash had robust hindlimbs and unlike other such ancient snakes, it crawled through the desert rather than swam through the ocean. In this sense, Najash is unique because of its terrestrial habitat.

In their new study, researchers led by Fernando Garberoglio from the University of Buenos Aires analyzed eight skulls, one of which was almost perfectly intact, found in northern Patagonia in Argentina. What makes the fossils particularly important is the fact that they’ve been preserved in three-dimensions, uncrushed, whereas most fossils are flattened like a pancake. As such, these fossils allowed the researchers to answer some longstanding questions about how snakes evolved their highly specialized skulls.

Fossilized skull of Najash found in Argentina. Credit: Fernando Garberoglio.

Micro-computer tomography scans revealed that Najash had a combination of lizard and modern snake features. It had a lizard-like cheekbone but lacked a bony arch connecting the skull the cheekbone. It also had intermediate features between snakes and lizards, such as a jaw point. According to the researchers, though, Najash had many of the flexible joints present in the skull of modern snakes.

“Snakes are famously legless, but then so are many lizards,” said Dr. Alessandro Palci, co-author of the study and a researcher at Flinders University.

“What truly sets snakes apart is their highly mobile skull, which allows them to swallow large prey items.”

“For a long time we have been lacking detailed information about the transition from the relatively rigid skull of a lizard to the super flexible skull of snakes.”

The 95-million-year-old fossils discovered in the La Buitrera Paleontological Area in Argentina also fill in the blanks in Najash‘s evolutionary tree.

Previously, scientists used to think that snakes trace their origins in blind, burrowing lizards. Scolecophidians, a group of living small, worm-like burrowing snakes, share common features and are considered the most primitive snakes alive today. But the newly described fossils show that skulls in the lineage of ancient snakes had nothing in common with scolecophidian snakes.

The newly constructed snake family tree remarkably shows that the slithering creatures had small hind legs for the first 70 million years of their evolution before limbless, modern snakes appeared.

“These primitive snakes with little legs weren’t just a transient evolutionary stage on the way to something better,” said Professor Mike Lee, a researcher at Flinders University and South Australian Museum.

“Rather, they had a highly successful body plan that persisted across many millions of years, and diversified into a range of terrestrial, burrowing and aquatic niches.”

The findings appeared in the journal Science Advances.

Scientists in India find new type of viper — and it looks stunning

The Arunachal pit viper was found in the state of Arunachal Pradesh in northeast India, close to the border with Bhutan and China. Image by Rohan Pandit.

Meet the Arunachal pit viper — or by its formal name, Trimeresurus arunachalensis. The viper was discovered by accident, when researcher Rohan Pandit and Wangchu Phiang, a member of the indigenous Bugun tribe, were carrying a biodiversity survey in north-eastern India. They found the snake by accident, although it was excellently camouflaged in the fallen foliage.

They weren’t sure what species it was, but they carefully studied it, noting its number and pattern of scales, and describing its anatomy. They also harvested DNA samples for analysis.

They sent the samples to Deepak Veerappan, currently a herpetologist at the Natural History Museum, London, who was then working at the Indian Institute of Science. To Veerappan, it was clearly a new species.

“I have been studying [the] morphology of snakes and lizards for a while now. The first time I saw the hemipenis of the snake [I realized] it is unique compared to its congeners,” he said. Veerappan also commented on its unusual coloring: perfect for hiding in between fallen leaves, despite a brightly colored orange belly.

“If you look at it from the top, it appears drab and camouflages well against leaf litter,” Pandit said. “But on the sides and the belly they have a bright orangish color.”

The Arunachal pit viper is well-camouflaged well in fallen leaves. Image credits: Rohan Pandit.

Despite the fact that only one specimen was found, the analysis strongly confirmed that it’s a new species. Genetic analysis indicates that it is closely related to the Tibetan pit viper (Trimeresurus tibetanus), a snake known only from Tibet, but features significant anatomical differences from this species.

However, although researchers are confident in the snake’s unique identity, they don’t know all that much about it. For instance, even though this snake was found on the ground, it’s not clear if it’s entirely terrestrial or also spends some time in the trees. We also don’t know what it eats or its general behavior. Most importantly, we don’t know whether this snake is threatened or not — it’s anyone’s guess how many Arunachal pit vipers there are in the wild.

Researchers are hoping to carry out a more detailed survey in the future. For now, however, this finding suggests that the forests in northeastern India may host numerous undiscovered species, of which we know even less than the Arunachal pit vipers.

Journal Reference: Captain, A., Deepak, V., Pandit, R., Bhatt, B., & Athreya, R. (2019). A New Species of Pitviper (Serpentes: Viperidae: Trimeresurus Lacepède, 1804) from West Kameng District, Arunachal Pradesh, India. Russian Journal of Herpetology26(2), 111-122.

Sea snakes can dive up to 250 meters deep — that’s 800 feet

Snakes — they’re slithering on the ground, climbing trees, and now they’ve taken to the deep sea. A team of Australian researchers spotted two snakes swimming at depths of 239 and 245 meters, respectively — smashing the previous record by a whopping 133 meters.

Record-setting dive of a sea snake swimming at 240 meters in the deep-sea ‘twilight zone’ taken in July 2017. Image credit: INPEX-operated Ichthys LNG Project.

There are more than 3,000 snake species on Earth, and there’s at least one on every continent except Antarctica. They come in all sizes, ranging from a meager 10 centimeters to a whopping 10 meters (in the case of the reticulated python). They also inhabit an impressive array of habitats. Most live on the ground, but some are arboreal, and some even dwell around caves. There’s also a group of sea snakes.

Sea snakes are a highly venomous family inhabiting the warm coastal waters from the Indian Ocean to the Pacific. They dwell almost exclusively in water, and most of them are completely unable to move about on land. They’re excellent swimmers, being capable of swimming several kilometers in one go, and they also dive to search prey. However, they still need to breathe, and researchers thought they only dive to shallow depths. Until now.

“Sea snakes were thought to only dive between a maximum of 50 to 100 metres because they need to regularly swim to the sea surface to breathe air, so we were very surprised to find them so deep,” says Dr Jenna Crowe-Riddell, lead author of the study and recent PhD graduate at the University of Adelaide’s School of Biological Sciences.

The snakes were filmed in 2014 and 2017 using a remotely operated vehicle (ROV). The fact that there were two separate observations of two different species suggests this is not a freak occurrence, and sea snakes are quite capable of diving to these depths.

At depths of over 200 meters, things start to change dramatically. Very little light passes through to that depth, which is why this area, technically called the mesopelagic zone, is also referred to as the ‘marine twilight zone.’

Water pressure is also substantial at that depth, and for surface creatures to go that deep, you need very specific adaptations. The temperature is also quite low — which is quite challenging to cold-blooded creatures like snakes. This raises new questions about the thermal tolerance and overall ecologic capabilities of these snakes.

“We have known for a long time that sea snakes can cope with diving sickness known as ‘the bends’ using gas exchange through their skin,” says Dr Crowe-Riddell. “But I never suspected that this ability allows sea snakes to dive to deep-sea habitats.”

This also highlights the need to better understand these environments, which are at risk from climate change, ocean acidification, and human activity — better conservation first requires better understanding.

The study “First records of sea snakes (Elapidae: Hydrophiinae) diving to the mesopelagic zone (>200 m)” has been published in Austral Ecology. https://doi.org/10.1111/aec.12717

Python.

A new study explains how snakes lost their legs

Efforts to understand how changes in the genome lead to changes in phenotypes is showing us why snakes don’t have legs.

Python.

Image via Pixabay.

While snakes and lizards belong to the same order (Squamata), they differ in one obvious aspect: snakes do not have limbs. New research is looking into the genetic changes that led to this outward difference. The study, led by Juliana Gusson Roscito at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden, Germany, also analyzed eye degradation in certain subterranean mammals.

Different within, different without

“The research consisted of an investigation of the genomes of several species of vertebrates, including the identification of genomic regions that changed only in snakes or subterranean mammals, while remaining unchanged in other species that have not lost their limbs or have normal eyes,” Roscito said.

Mammals with degraded visual systems seem to have shed certain genes from their genomes — mainly those associated with the formation of the crystalline lens and photoreceptor cells in the eyes. This process was very likely gradual, taking successive mutations during the evolutionary process but, eventually, these genes completely lost their ability to encode proteins. However, Roscito says, this isn’t what happened to snakes — they haven’t lost the genes associated with limb-formation.

“To be more precise, the study that sequenced the genome of a snake did detect the loss of one gene, but only one,” she adds. “Therefore, the approach we chose in our research consisted of investigating not the genes but the elements that regulate gene expression.”

Gene expression — whether a gene is ‘active’ or not — depends on regulatory elements that are outside of the gene itself. These basically allow or block the information inside the gene to be transcribed into RNA and then be carried off to generate a protein. This process is regulated by cis-regulatory elements (CREs), sequences of nucleotides in DNA placed near the genes they regulate. These CREs can significantly alter a genome’s functionality via the genes they block or enable.

“A regulatory element can activate or inhibit the expression of a gene in a certain part of the organism, such as the limbs, for example, while a different regulatory element can activate or inhibit the expression of the same gene in a different part, such as the head,” Roscito explains.

“If the gene is lost, it ceases to be expressed in both places and can often have a negative effect on the organism’s formation. However, if only one of the regulatory elements is lost, expression may disappear in one part while being conserved in the other.”

However, it’s pretty difficult to accurately identify CREs. Genes all follow a certain structural pattern, having base pairs at each end of the gene — so they’re easy to delineate. CREs have to be identified indirectly, usually by comparing DNA sequences from different species. That’s exactly what the team did for this study: they compared the genomes of snakes with those of various other reptile and vertebrates (that have limbs). As “genome sequences for reptiles with well-developed limbs are scarce”, the team writes, they sequenced and assembled the genome of Salvator merianae, the tegu lizard, themselves. This is “the first species of the teiid lineage ever sequenced,” the authors add.

Gold Tegu.

The gold tegu, Tupinambis teguixin.
Image credits Joel Santana.

Using this genome as a reference, the team looked at the genomes of several other species. These included two snakes (boa and python) three other limbed reptiles (green anole lizard, dragon lizard, and gecko) three birds, an alligator, three turtles, 14 mammals, a frog, and a coelacanth (a very rare type of fish). They ‘aligned’ these 29 genomes together and used that as a basis for their analysis.

Armed with 5,000 possible candidates for regulatory elements in the DNAs of these species, the team looked at the genomes of several species of snakes. They managed to narrow down the search to a set of CREs whose mutation may have led to the disappearance of limbs in snakes.

“There are several studies concerning a well-known regulatory element that regulates a gene that, when modified, causes various defects in limbs. Snakes have mutations in this CRE. In a study published in 2016, the mouse CRE was replaced with the snake version, resulting in practically limbless descendants,” Roscito says. “This was a functional demonstration of a mechanism that may have led to limb loss in snakes.”

“However, this CRE is only one of the regulatory elements for one of several genes that control limb formation. Our study extended the set of CREs. We showed that several other regulatory elements responsible for regulating many genes have mutated in snakes. The signature is far more comprehensive. An entire signaling cascade is affected.”

The paper “Phenotype loss is associated with widespread divergence of the gene regulatory landscape in evolution” has been published in the journal Nature Communications.

Contrary to popular belief, drought actually leads to fewer snakebites

There are many myths and popular beliefs regarding snakes — but this one certainly isn’t true.

Image credits: Noah Loverbear.

A few years ago, Grant Lipman, an emergency medicine physician at Stanford Medicine, was jogging on the hills around campus. It was a terrible drought, but that wasn’t the highlight of his day — the highlight would be a 3-foot-long rattlesnake lying on the trail. He discussed this with his colleagues, and one of them reported a similar sighting. This got Lipman thinking. Could the drought be in any way connected to the rattlesnakes they were seeing or was it simple coincidence?

“I wondered if there are more snakebites during droughts,” said Lipman, clinical associate professor of emergency medicine at the Stanford School of Medicine, who routinely treats patients with venomous snakebites.

So he started work and worked with a team of researchers to answer the question.

Everyone sure seemed to believe that droughts exacerbate snakebites. “Deadly Snakebites Set to Skyrocket During Record-breaking Drought,” read one article in 2018 in the Daily Mail. Another, “Snakes Cross Paths with Humans in Bay Area Due to Drought,” was reported on ABCNews.com in 2015.

It seemed to make some sense. The idea was that snakes are more active during warm weather, and they also need to wander more during droughts. But the scientific information was pretty scant on the subject.

The results, funnily enough, showed that the opposite is true: during dry spells, snakebites actually go down.

Lipman and colleagues analyzed 20 years of snakebite data from every phone call made to the California Poison Control System from 1997 to 2017. In total, 5,365 snakebites were reported, from rattlesnakes. Five of them were fatal. The number of bites varied significantly from county to county, ranging from 4 to 96 per one million people.

It was actually rain that seemed to get the snakes out.

Snakebites went down by 10% following a drought but increased by 10 percent following high levels of precipitation. Researchers believe that this happens because, during the rainy season, shrubs grow more, which also favors rat populations — snakes’ favorite prey.

The study isn’t frivolous — this isn’t only about satisfying a curiosity. It can be quite important, and potentially even save lives. By knowing when snakebites are more and less likely to happen, authorities and hospitals can stockpile and transfer antivenom — which is often a scarce commodity, accordingly.

But Lipman, who has vast experience on treating this type of bite, says that the best way to reduce the frequency of bites is to simply be more careful. Snakes never go out of their way to attack anyone, quite the opposite — they go out of their way to avoid people as much as they can.

“The most common comment I usually hear from snakebite victims in the emergency room is: ‘I was just minding my own business,'” Lipman said. “Usually, though, it’s the snakes that were minding their own business, having a nice nap. It’s people who tend to disturb them.”

Venomous creatures could hold the key to innovative drug therapies

Venomous creatures are generally regarded as threatening and dangerous — and quite often, they really are. But in a new study, researchers explain how understanding their venom and how it works could lead to new treatments for things like diabetes, autoimmune diseases, chronic pain, and other conditions.

In 326 BCE, Alexander the Great encountered lethal arrowheads in India that, based on the symptoms of dying soldiers, were most likely laced with venom from the deadly Russell’s viper.”

That’s how the new study begins its foray into how venom has been used. But it hasn’t been all bad — venom (or rather, specific components isolated from venom) can be used for treatment.

“By contrast, snake venom has been used in Ayurvedic medicine since the 7th century BCE to prolong life and treat arthritis and gastrointestinal ailments, while tarantulas are used in the traditional medicine of indigenous populations of Mexico and Central and South America,” the study continues.

So then, why haven’t we explored this more?

Venomous species account for about 15% of the planet’s biodiversity and inhabit virtually all of the Earth’s ecosystem. However, venom remains a critically understudied substance, especially because it’s generally produced in quantities that are too small to study, and the extraction process is extremely tedious. But technical innovations have allowed for better and better analysis using smaller and smaller quantities.

Nowadays, technology has reached a level where researchers are able to uncover important characteristics of venom even with realistic, small amounts. This, researchers say, raises new opportunities to study how compounds from venom could enable us to treat illnesses.

“Knowing more about the evolutionary history of venomous species can help us make more targeted decisions about the potential use of venom compounds in treating illnesses,” said lead author Mandë Holford, an associate professor of chemistry and biochemistry at The Graduate Center of The City University of New York (GC/CUNY) and Hunter College. “New environments, the development of venom resistance in its prey, and other factors can cause a species to evolve in order to survive. These changes can produce novel compounds — some of which may prove extremely useful in drug development.”

While the main focus is deriving new treatments, this isn’t the only research avenue scientists are pursuing.

For instance, peptides derived from venomous sea anemones could help treat autoimmune diseases, while neurotoxins derived from sea snails provide a non-addictive treatment for chronic pain. Scorpion venom might also be useful — chlorotoxin from the deathstalker scorpion could be the basis for a surgical tumor-imaging technique — while spider toxins could help devise eco-friendly insecticides.

To date, only 6 venom-based drugs have been approved by the FDA, but recent work is revealing many more promising therapy candidates.

There’s certainly a lot to learn from venom, and the time has never been better.

The study has been recently published in Science.

Snake fossil.

First-ever baby snake fossil discovered beautifully encased in amber

Researchers have unearthed the very first baby snake fossil in history — and it’s teaching us a lot about how snakes’ biology and ecological role evolved.

Snake fossil.

The piece of amber encasing the fossil, alongside a synchrotron x-ray image of the snake skeleton within. Scale bar is 10 mm.
Image credits Lida Xing et al., 2018, Science Advances.

Scientists digging through the Angbamo site in the Kachin Province, Myanmar, have unearthed a 99 million-year-old baby snake, beautifully encased in amber. The fossil, dating back to the Late Cretaceous period, is the oldest baby snake fossil ever found to date, and the first snake we know of that lived in a forest.

Amber’d

The small Southeast Asian country of Myanmar is a known treasure trove of fossils. The area previously yielded the tail of a feathered dinosaur, their ticks, as well as a baby frog, all encased in the beautiful amber that the region is famed for. But Myanmar’s soil has yet to reveal all its treasures, judging by a recent discovery — that of a baby snake, similarly preserved in fossilized tree sap. Alongside this, the researchers also found a second snake fossil (also encased in amber) likely containing part of the shed skin of another, much larger snake. It is unclear so far if the two are members of the same species.

Snakes today are a very successful group. They’ve spread across all continents except Antarctica, and number roughly 2,900 different species. However, they weren’t always so pervasive; they only emerged on dry land during the Cretaceous period.

The new fossil shows us that by around 99 million years ago, snakes had found their way from swamps or sea shores to become fully-terrestrial in forested environments. The second fossil only consists of skin and scale fragments, but are still distinctly snake-like, its discoverers report. This second fossil shows dark and light patterns of coloration and likely formed from the remains of an older, larger individual.

Both are extremely similar to snake species living today, a testament to how well-adapted little these little, slithering predators are to their ecological niche.

Snake skin.

Photographs of snake shed skin. Scale bar, 5 mm, 1 mm, 1 mm, respectively.
Image credits

Using uranium-lead dating, a research team led by Lida Xing from the China University of Geosciences and Michael Caldwell from the University of Alberta dated the fossils to about 99 million years old. A technique called synchrotron x-ray micro–computed tomography allowed the researchers to get a close look at the tiny specimens inside the amber without having to break them apart.

The baby snake was just hatching when it died, the team report. It’s very tiny, at some 47.55 mm (1.8 inches) in length, but for reasons yet unknown it’s missing a head. Still, based on lab imaging, the team was able to document nearly 100 vertebrae, alongside bits of rib and other anatomical features. While very similar to other snakes from the Cretaceous, it’s distinct enough, the team argues, to warrant receiving its own name. They settled on Xiaophis myanmarensis, where “Xiao” is the Chinese word for “dawn,” “ophis” the Greek word for “snake”, and “myanmarensis” for the place of its discovery, Myanmar.

Neither of the snakes is significantly different from species today — the earliest direct evidence so far that the biology of snakes has remained relatively unchanged over the last 100-or-so million years.

The fossils are further relevant as they’re the earliest evidence of Mesozoic (the larger Era which includes the Cretaceous) snakes living in forests. This indicates “greater ecological diversity among early snakes than previously thought,” the study notes. The link was established by the remnants of insects and plant material found in association with the snake fossils.

The paper “A mid-Cretaceous embryonic-to-neonate snake in amber from Myanmar” has been published in the journal Science Advances.

Scientists auction snake names to save them

The official names of five snakes are up for auction — and the money raised will go towards saving them.

The new species Sibon bevridgelyi is arguably the prettiest of the lot. Image credits: Alejandro Arteaga.

Want to show someone you love them? Or even better, would you like to name a snake after your ex? Or perhaps you just want to help save a few snake species? Well, then you just missed your chance. A team of biologists has auctioned the naming rights of five newly discovered snakes and the money might just save them from extinction.

With four out of five snakes already at risk of extinction, it seems like a sensible thing to do. The international research team decided to auction off their naming rights, and with the money they gain, they hope to purchase and save a previously unprotected 72 hectares (178-acre) plot of land where some of these species live. If everything goes according to plan, Fundación Jocotoco is to add the purchased plot to the Buenaventura reserve, thereby expanding the only protected area.

The snakes themselves are rather unique. They have an unusual taste for snails, which has led to a remarkable adaptation: their jaws have developed in such a way that they can suck the viscous slimy body of a snail right out of its shell. The species are described in a new study, where Alejandro Arteaga, an Ecuadorian-Venezuelan Ph.D. student at the American Museum of Natural History and scientific director of Tropical Herping and his team present their unusual habits.

[panel style=”panel-default” title=”How to find a new species of snake” footer=””]

[/panel]

Three of the species were discovered in rainforests in Ecuador between 2013 and 2017, while the other two were found in drier environments. Having made the highest bid at the auction, the Rainforest Trust (RT) and Bob Ridgely got to name three of the five new snakes. Ridgely, who is a renowned conservationist, has opted for the following names:

  • Dipsas georgejetti was chosen to honor George Jett, who supported the inception of Fundación Jocotoco’s reserves in Ecuador;
  • Dipsas bobridgelyi, after himself; and
  • Sibon bevridgelyi (Bev Ridgely’s Snail-Eater) to honor his father.

The remaining two species, Dipsas oswaldobaezi and Dipsas klebbai, were named after Dr. Oswaldo Báez and Casey Klebba, respectively, in recognition for their passion for Ecuador’s biodiversity and conservation.

The species Dipsas klebbai is the only one of the newly described species not currently threatened with extinction. Image credits: Alejandro Arteaga.

It’s a very unusual and creative technique, which to be honest, also seems very practical — the benefits are obvious.

“We had to let people know that these cool snakes exist,” Alejandro said, “and that these species might soon stop to exist, and we need people’s help to protect the snake’s habitat.”

“Several companies let you name a star after a loved one,” he noted, “but, generally, such names have no formal validity. Naming an entire species after someone you love or admire is different. With few exceptions, this is the name that both the general public and the whole scientific community will use. So, why not let people choose the name of a species in exchange for a donation that protects its habitat?”

Naming species is a part of the very core of biological studies and is more than just a symbolic gesture — once a species is named, it stays that way. Renaming species is possible, but it’s very rare, and generally only happens when a species has been misclassified or needs to be reclassified.

However, it should be noted that making a public auction can also have some unexpected consequences. Who knows — the next new species of snake might be called Snakey McSnakeface.

Journal Reference: Arteaga A, Salazar-Valenzuela D, Mebert K, Peñafiel N, Aguiar G, Sánchez-Nivicela JC, Pyron RA, Colston TJ, Cisneros-Heredia DF, Yánez-Muñoz MH, Venegas PJ, Guayasamin JM, Torres-Carvajal O (2018) Systematics of South American snail eating snakes (Serpentes, Dipsadini), with the description of five new species from Ecuador and Peru. ZooKeys 766: 79-147. https://doi.org/10.3897/zookeys.766.24523

Why do snakes flick their tongues?

Despite popular belief, snake tongues have no receptors for taste or smell. However, they flick their tongues to collect chemicals from the air or ground, using the so-called Jacobson’s Organ in the top of the mouth.

Snakes are terribly odd creatures, with their cold-blooded no-legs approach to life, but they’ve been around for over 100 million years, so they must be doing something right. Among the distinctive features of these elongated, carnivorous reptiles is their forked twin tongue.

Folklore and old explanations

Since the dawn of mankind’s interaction with snakes, we’ve noticed their eerie forked tongues flicking in and out — but why do they do it? Aristotle was seemingly fascinated by snakes and wrote about them on several occasions. Somehow, he managed to be very wrong, and yet also very close to the real answer. He wrote that “nature does not do anything in vain” and does “what is best among the possibilities,” something which is somewhat consistent with the principles of evolution. About the tongue, he wrote that it provides snakes with “a twofold pleasure from savors, their gustatory sensation being as it were doubled.”

In the 17th century, the idea that snakes catch insects with their tongue was popularized, and even though this has never been observed to be the case, it was still widely believed. However, this is true for other reptiles — most notably chameleons.

The Italian astronomer Giovanni Hodierna thought snakes use their tongues to clean dirt from their nose, which is a more reasonable explanation, though equally unlikely.

Two myths have also been perpetuated about snake tongues. The first is that they use the tongue to cover the prey in saliva before swallowing it. However, even a superficial investigation will reveal that the delicate tongue is neither well-suited or capable of such an act. The other myth is that it is a stinger, or the source of the snake venom, something which again, was disproven by autopsies since the Renaissance. This latter belief was probably popularized by quotes in the Bible and in Shakespearean literature. It’s surprising that so many myths still surround this phenomenon, but it’s probably understandable since snakes themselves are surrounded by a great deal of myth and folklore.

Why snakes really flick their tongue

A thorough investigation of snake behavior will reveal that through the tongue, the snake gets some understanding of its surrounding. This was determined by the investigations of French naturalist Bernard Germain de Lacépède in the early 1800s. Various 19th-century scholars have believed the tongue to be an organ of smell, taste, or even vibrations. However, these theories were displaced by thorough experiments.

More recent studies have learned that a snake tongue picks up particles or odors from the air. The two tips of the tongue are then introduced into the corresponding pair of what is called Jacobson’s organ, where they evoke different signals which are then transmitted electrically to the brain.

Keep in mind that this is neither a sense of smell nor taste — the tongue does not have receptors for smell or taste. It simply picks up the chemicals from the air or ground and passes them to Jacobson’s Organ.

[panel style=”panel-info” title=”Jacobson’s Organ” footer=””]The organ (also called the Vomeronasal organ, or VNO) was actually discovered in the 18th century, but its purpose wasn’t properly understood at the time. The organ is mainly used to detect pheromones, chemical messengers that carry information between individuals of the same species. Snakes have very well developed Jacobson’s organ, which allows them to sense a wide variety of chemicals.

But snakes aren’t the only creatures to have this biological feature. Many mammals also have it, and it is typically involved in the so-called flehmen response — a behavior in which an animal curls back its upper lip exposing its front teeth, inhales with the nostrils usually closed and then often holds this position for several seconds. The flehmen response is often used by horses and cats. However, oscillating tongue flicks are unique to snakes.

In humans, the VNO remains an area of active research and a controversial subject. The presence of vomeronasal organ has been observed in fetuses, though several studies found that it regresses as the fetus develops. It’s unclear if the VNO continues into adult life, as some studies have found evidence of it, while others have not. Furthermore, even if it does exist, it’s not clear that it is active and functional — even though chemical communication has been proven to exist between humans.[/panel]

So, snakes flick their forked tongues to pick up chemicals from the air or from the ground, something which is akin to smelling but is really not the same as smell. But this doesn’t really tell the whole story.

Advanced features of the snake tongue

While this explains why snakes flick their tongue, we still haven’t discussed why their tongue is forked — and there’s a very good reason for it.

Because it is forked, it can collect information in two places at once. This allows the snakes to create a chemical gradient of sorts, which gives them a sense of direction. In other words, snakes use their forked tongues to navigate the chemical world in 3D. It’s the same principle with owls, who developed asymmetrical ears to collect sounds in 3D. This makes it much easier for snakes to pick up and follow trails left behind by other animals.

This theory was confirmed in the 1930s, in an age before the ethical use of animals in research was regulated. German biologist Herman Kahmann cut off the forked parts of a snake tongue. He found that while the snakes were still efficient at picking up chemicals, they were much less able to follow trails.

More ethical studies have shown that the snake is effective in following not only the trail of potential prey — but also that of mates. In the 1980s, snake biologist Neil Ford at the University of Texas at Tyler followed male garter snakes as they were chasing the trail of females. He found that if both tips of the male tongue fall within the trail left by the female, the snake continues his route. But if one side falls outside of it, the snake turned his head away from that side, accurately following the female trail. Snake ecologist Chuck Smith at Wofford College also found that male Copperheads have longer, more deeply-forked tongues than females, which seems to support this theory.

Also, it was once thought that since Jacobson’s organ is forked just like the tongue, the tongue delivers the chemicals directly to the organ, but X-ray videos have revealed that this is not the case. It seems that the tongue simply deposits the chemicals on the bottom of the mouth, and when the mouth closes, the bottom and the top of the mouth, where Jacobson’s organ is located, come into contact.

Recent studies have also sought to quantify snake tongue flicks by analyzing tongue flick behavior. Gheylen Daghfous and his colleagues from the Université de Montreal have found two different tongue flick behaviors: one when the snakes picked up chemicals from the air, and another one when they pick chemicals up from the ground. They explain this as a specialized behavior which optimizes how chemicals are picked up from different environments.

Odor dispersion and how it is picked up by different creatures is still an area that’s poorly understood. While we can now say we truly know why snakes flick their tongues, the intricacies of this process are still not fully understood, and future studies will no doubt reveal even more about the impressive creatures we call snakes.

Python moms take care of their offspring, surprising researchers

When it comes to parental love, snakes don’t really top off the list. Most snakes just lay their eggs in a safe place, cover them with dirt, and hope for the best. Snakes which give birth to live young still don’t really care for them and, overall, you wouldn’t expect snakes to win any parenting awards. But according to a new study, at least one species is trully involved in raising its offspring: the southern African python.

A clutch of Southern African python babies basking in the sun. Credit: Graham Alexander/Wits University.

The African rock python (Python natalensis) is one of the 11 living species of python and the largest snake species in Africa. It can be found in a variety of habitats, from forests to near deserts, killing and eating animals as big as an antelope. These pythons are also opportunistic creatures, installing themselves in aardvark burrows for nesting and laying eggs. Professor Graham Alexander, a reptile researcher at the Wits School of Animal Plant and Sciences & the University of the Witwatersrand in Johannesburg, wanted to peek inside these burrows. He installed radio transmitters and infrared cameras inside, following 37 pythons in the Dinokeng Game Reserve, 8 of which laid eggs during the study.

He reports a set of interesting behaviors from the mother pythons. For starters, after they laid eggs, their color tended to become darker. Snakes are unable to regulate their temperature through metabolism, so they bask in the sun and absorb heat — and turning darker allows them to heat up faster. After they raise their temperature (to up to 40 degrees Celsius / 104 Fahrenheit) they slither back to the burrows to keep the eggs warm during the night.

But here’s the interesting thing: they also do the same thing after the snakelets are born, gathering heat during the day, and returning during the night to help keep the young ones warm. They do this four about two weeks before finally departing and leaving the offspring to fend for themselves. This is the first time an egg-laying snake has been observed exhibiting any maternal behavior.

“This is the first-ever report of maternal care of babies in an egg-laying snake,” says Alexander. “I was amazed by the complex reproductive biology of this iconic snake,” said Alexander.

So why do they do it? It’s not particularly clear, though researchers have a few clues. After hatching, the young pythons are still packed full of undigested egg yolk. While this is advantageous, as it means they don’t need to hunt in their earliest days, it also makes them sluggish and vulnerable to predators and cold temperatures. The python mother keeps predators away and also shares her body heat, keeping the youngling warm. This also makes sense, since the study was carried out in the southern range of the snakes, where temperatures are lower than in the other parts of their habitat.

However, this extra care comes at a great price for the mothers: during this period, they are unable to hunt, losing up to 40% of their body weight. Some of them never truly recover, Alexander comments.

“All of this takes its toll on mother pythons: they take a long time to recover after breeding and so can only produce a clutch every second or third year, depending on how many meals they are able to catch in the months after leaving the nest. Some of them never recover.”

Another surprising finding was that male snakes follow receptive females for an impressively long period of time.

“In one case, one male was recorded following a female for more than 2 km over a three-month period,” says Alexander.

Journal Reference: G. J. Alexander, Reproductive biology and maternal care of neonates in southern African python (Python natalensis), Journal of Zoology (2018). DOI: 10.1111/jzo.12554

Green snake.

Research of snakes’ straight-line movement could power the rescue bots of the future

Unbeknownst to most people, snakes have the ability to crawl in a straight line without any S-like undulations. Despite the first study on the matter being published in the 1950s, it’s an ability we still don’t properly understand. New research from the University of Cincinnati comes to plug that hole in our knowledge.

Green snake.

Image via Pixabay.

Be it swimming, climbing, and crawling, snakes typically move about by bending into S-like coils or using the tip of their tail to push off objects. But snakes hide an ace up their sleeve, despite lacking sleeves. This might surprise (and further scare) you in a chance encounter. They can also move forward in a straight line without any wiggling, bending, or squiggling.

Known as “rectilinear locomotion”, which is fancy for ‘moving in a straight line’, this ability allows the murderous meat tubes to crawl in narrow burrows in search of prey. We know they do it, but we don’t really know how, so University of Cincinnati biologist Bruce Jayne set out to study the mechanics of this type of movement.

S-s-slitherin’

“It’s a very good way to move in confined spaces,” Jayne says about rectilinear locomotion. “A lot of heavy-bodied snakes use this locomotion: vipers, boa constrictors, anacondas and pythons.”

Jayne has previously studied the mechanics behind three other kinds of snake movement called concertina, serpentine, and sidewinding locomotion. Rectilinear motion, he says, has received less attention both from himself and other researchers, so it was particularly poorly understood.

Types of snake movement

Types of snake movement. Rectilinear locomotion is named ‘caterpillar‘ here.
Image via Pinterest.

Most research on the subject was performed in 1950 by biologist H.W. Lissmann. He hypothesized that snakes combine patterns of muscle movement with their loose, flexible belly skin to scoot forward without having to bend their spine. However, Lissmann’s findings were never expanded upon, so, Jayne adds, “it’s been almost 70 years without [rectilinear] locomotion being well understood.”

Together with graduate student and co-author Steven Newman, Jayne put Lissmann’s hypothesis to the test using modern equipment. The team worked with boa constrictors, big-bodied snakes that are known for traveling in a straight line across forest floors. They filmed the snakes’ movements across marked horizontal surfaces with high-definition digital cameras and used electrodes to record the electrical impulses generated by groups of their muscles. The resulting electromyogram (similar to an EKG but for your muscles — ‘myo’ — instead of the heart) revealed that rectilinear locomotion requires a close coordination between the snake’s muscles, skin, and skeleton.

[Read More: For beautiful snake photography and additional information, give our chat with wildlife photographer Marius Iancu a read]

The researchers also added dots on the sides of the snakes to use as a reference for the subtle movements of their skin. The video revealed that as snakes inch forward, the skin on their belly flexes much more than that over its back and ribcage. Similarly to treads on a caterpillar track, the scales on their belly provide traction with the ground. After the animal is securely lodged in place, muscles pull its internal structures forward in an undulating pattern. Groups of muscles constrict starting from the head towards the tail in sequence to maintain this movement pattern, and key to the whole process are costocutaneous (from ribs to skin) muscles.

Snake skeleton.

And they do not lack for ribs.
Image credits Denis Doukhan.

Snakes are able to maintain this motion with a high degree of fluidity at high speeds, the team reports, allowing them to move seamlessly along at any speeds.

“The vertebral column moves forward at a constant rate,” Newman said. “One set of muscles pulls the skin forward and then it gets anchored in place. And opposite antagonistic muscles pull on the vertebral column.”

Still, the authors note that rectilinear locomotion seems to be a ‘low gear’ for snakes, who use it chiefly when they’re in a relaxed state. When prodded or startled, they will generally revert to concertina or serpentine motion.

Belly-walking

Rectilinear locomotion brings certain advantages to the table, especially for predators such as snakes that hunt rodents and other animals who burrow underground for safety. Newman explains that “you can fit in much narrower holes or tunnels by moving this way” compared to the traditional S-like slithering — creating a powerful selective advantage for the trait in the ancestors of snakes, who were also borrowers, he adds.

Eastern Indigo Snake.

All your burrows are belong to us.
Image via Wikimedia.

Overall, the team reports that Lissmann’s findings in 1950 were largely correct. However, he also “hypothesized that the muscle that shortens the skin was the mechanism that propels a snake forward.”

“He got that wrong,” Jayne said. “But given the time he conducted the study, I marvel at how he was able to do it. I have tremendous admiration for his insights.”

The research provides a lot of material for robotics engineers trying to design better snake-like robots. Such constructs are uniquely suited to inspect pipelines (as they can easily fit inside them) or work with underwater equipment (as their sub-like shapes allow them to better withstand high-pressures). Alternatively, snake-like rectilinear motion could be a tremendous boon for search-and-rescue robots that have to grapple with debris and confined spaces when searching for survivors in collapsed buildings.

Jayne plans to continue his work with snakes in the future. By testing the limits of their mobility, Jayne hopes we can understand more about snake’s motor controls — which in turn can help us elucidate how we humans execute complex, coordinated movements.

“Even though all snakes have the same body plan, there are fully aquatic snakes, snakes that move on flat surfaces, snakes that move in a horizontal plane, snakes that climb. They go everywhere,” he said.

“And the reason they can go everywhere is they have so many different ways of controlling their muscles.Even if the animal had the physical strength to do something, it wouldn’t necessarily have the neural control. That’s pretty intriguing. “

The paper “Crawling without wiggling: muscular mechanisms and kinematics of rectilinear locomotion in boa constrictors” was published in the Journal of Experimental Biology.

 

Snake fungal disease could be a global threat, much bigger than we thought

Less than a year after a series of studies brought snake fungal disease into the spotlight, researchers believe the problem might be much bigger than anticipated.

Eastern racer (Coluber constrictor) showing signs of fungal skin infection. Obvious external abnormalities are an opaque infected eye, roughened crusty scales on the chin, and several discolored roughened scales on the side of neck. Credits: USGS National Wildlife Health Center/D.E. Green.

In June, scientists wrote about a dreadful fungal disease ravaging rattlesnakes in North America. Not long after that, similar findings were also reported in Europe. Now, a new study shows that the disease affects snakes regardless of their ancestry, physical characteristics, or habitats. This could mean that it’s much more widespread than previously thought, potentially affecting snakes all around the world, as it has already been documented in 23 wild species in the United States (including rat snakes, milk snakes, gartersnakes, and viperids) and three species in Europe.

“This really is the worst-case scenario,” said Frank Burbrink, an associate curator in the Museum’s Department of Herpetology and the lead author of the publication. “Our study suggests that first responders shouldn’t just be looking for certain types of snakes that have this disease, but at the whole community. All snakes could become infected, or already are infected.”

The main culprit behind the disease is a pathogen called Ophidiomyces ophiodiicola, which causes skin lesions, scabs, and crusty scales and can cause fatal infections in some cases. However, researchers aren’t sure if the pathogen alone is to blame, or if other environmental factors or pathogens also play a part.

Snakes aren’t the only ones to fall victim to fungal diseases. In recent years, similar issues have wreaked havoc on populations of frogsbats, and salamanders — snakes are only the latest

“Some of the most devastating wildlife diseases ever documented, such as white-nose syndrome in bats and chytridiomycosis in amphibians, are caused by fungal pathogens,” said Jeffrey Lorch, a microbiologist with the U.S. Geological Survey (USGS) National Wildlife Health Center. “These diseases have had such great impacts because they affect multiple species, and it now looks like the same is true of snake fungal disease.”

However, with snakes being hidden away for a few months a year and highly reclusive during the rest, studying them isn’t easy, and so biologists aren’t really sure how bad things really are. Prevention is better than treatment, but that may no longer be an option.

Journal Reference: “Host susceptibility to snake fungal disease is highly dispersed across phylogenetic and functional trait space” DOI: 10.1126/sciadv.1701387 ,

 

Snake fungal disease observed in Europe for the first time

Bad news for European snakes — the dreaded fungal disease already reported in the US seems to have spread to Europe as well.

Grass snake (Natrix natrix) with skin lesions due to snake fungal disease. Image credits: Zoological Society of London.

Just a few days ago we were telling you how fungal diseases — already so menacing for frogsbats, and salamander — are starting to threaten snakes as well. At this point, it’s unclear if a single pathogen is responsible or if it is a series of ailments rather than one, but the most likely culprit seems to be a pathogen called Ophidiomyces ophiodiicola, which causes skin lesions, scabs, and crusty scales and can cause fatal infections in some cases.

So far, over 30 species have been found suffering from the diseases in the US, with some species being more vulnerable than others; specifically, rattlesnakes have been found to be highly at risk. Humans, pets, and livestock are not at risk to the disease. Ophidiomyces ophiodiicola is only known to infect snakes. Now, researchers have found evidence of snake fungal disease (SFD) in Europe as well.

After analyzing samples gathered from wild snakes (the disease was already known in some zoos) from 2010 to 2016 in the United Kingdom and the Czech Republic, researchers have now definitely confirmed the existence of the disease on the Old Continent. Lead author and wildlife veterinarian Dr. Lydia Franklinos said:

“Our team at ZSL found evidence of SFD in grass snakes (Natrix natrix) from the UK and a single dice snake (Natrix tessellata) from the Czech Republic. The analysis found that the fungus strains from Europe are different to those previously identified in North America – suggesting that rather than being introduced across the Atlantic, or vice versa, the disease could have been present below the radar in European snakes for some time.

Grass snake skin shed with lesions positive for Ophidiomyces ophiodiicola. Image credits: Zoological Society of London.

Detailing their work in an open-access paper published in Scientific Reports, they’ve screened 33 carcasses and 303 molted skins from wild snakes, finding the fungus in 26 (8.6%) specimens across the period of collection. In most cases lesions were mild, but in some cases, researchers believe they contributed or were even decisive for fatality. It’s hard to estimate just how much damage the diseases is causing, and scientists call for more studies to paint a clearer picture. The reclusive nature of snakes certainly isn’t helping in this case.

“Of all terrestrial vertebrate wildlife, we probably know least about health conditions that affect reptiles such as snakes, so this study represents an important milestone and one that will hopefully encourage greater focus in understanding the threats facing these animals,” Franklinos adds.

Fungal pathogens are emerging worldwide at an alarming rate, and kind of snuck up on us. It’s important to understand just how much it spread across the world, and how it affects organisms different based on their environment. This might be the first step towards starting to fight it. Dr. Jeffrey Lorch, a microbiologist with the USGS National Wildlife Health Center and the study’s co-author, said:

“The fungus that causes SFD is already known to occur across the eastern half of the U.S. and infect over 20 species of snakes. Comparing how SFD affects wild snakes on different continents may help us pinpoint the factors causing the disease to emerge and help managers identify mitigation strategies.”

You might think that snakes aren’t that important, or that this is a natural thing and we should just let it follow its course. Snakes aren’t the most popular animals out there either, which likely contributes to the big gaps we have in our understanding of them. But like them or not, snakes play a vital role in ecosystems. Most snakes are middle-order predators, which means they eat some animals and are in turn eaten by others, filling a very important niche.

It’s not clear why this disease is emerging now, either. It could be a foreign, introduced pathogen, or it could be that various species across the planet are developing it independently. That remains to be established by future research. There is a good chance that environmental changes have rendered the snakes unable to defend themselves against the pathogen, or that at least, the changes have weakened them.

Several countries are already working on ways to improve reporting on such matters. In the UK, you can check out the Garden Wildlife Health Project for instance. The full paper is here — open access and published by the Institute of Zoology.

Fungal disease ravages American rattlesnakes

Scientists still haven’t found a cure or a solution for the disease, with cases being confirmed in at least fifteen US states and several countries in Europe.

Northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection, captured from an island in western Lake Erie, Ohio, in August 2009 (case 22747). Photograph by D.E. Green, USGS National Wildlife Health Center.

According to National Geographic, fungal diseases have run rampant in the past few decades, attacking populations of frogs, bats, and salamanders. Snakes are the latest to fall victim to such a disease. Although it’s hard to gauge its damage due to the cryptic nature of snakes, researchers fear consequences can be devastating, especially if action is delayed.

Snake fungal disease is caused by a pathogen called Ophidiomyces ophiodiicola, with the most common symptoms including skin swelling, crusts, and nodules of the skin. However, lab studies have also revealed other fungi associated with Snake Fungal Disease (SFD), so it’s hard to say that there’s only one pathogen responsible. Skin lesions often occur, which can develop into full-grown blisters that disfigure snakes, potentially leaving them unable to feed themselves.

snake fungal disease

Milk snake (Lampropeltis triangulum) showing signs of fungal and bacterial infections, captured in Westchester County, New York, February 2013 (case 24281). Photograph by D.E. Green, USGS National Wildlife Health Center.

So far, over 30 species have been found suffering from the diseases, but one group of snakes is especially vulnerable to the disease: rattlesnakes.

We don’t know why rattlesnakes are more threatened by the fungal diseases, just as we don’t know why these diseases sometimes pop up more than other times. Jonathan Kolby, an American biologist and conservationist, comments:

“It just seems one after the other that these emerging fungal diseases are appearing in different types of animals, yet they’re spread enigmatically,” said Kolby, who is also a National Geographic explorer. “We don’t know where exactly they came from or why they suddenly appear to be more virulent.”

As it’s often the case with such infections, it’s not necessarily a case of the pathogen growing stronger, but rather a case of the host growing weaker. If this is at work here, then it could mean that snakes are under environmental stresses which don’t allow them to defend properly. Moving on with that line of thought, if we want to find the cause of this disease, we have to look at what changed in their habitat. A likely culprit is climate. Jeffrey Lorch, a microbiologist at the United States Geological Survey, explains:

“It could be that if we’re experiencing cooler and wetter springs in which snakes have to spend more time underground and not be able to reach those high body temperatures necessary to fight off infection that it could leave them more susceptible,” he said.

Habitat destruction is also eating away at the snakes’ lifestyle. The problem, again, is that we still have many gaps in our understanding of snakes, because they’re notoriously difficult to study — they spend most of the day hidden and hide underground when it gets too cold. To make things even worse, snakes aren’t particularly popular, to say the least. As a result, the snake fungal disease research community is quite small, and data is scarce and unreliable.

Jennifer Moore and her research team at the Pierce Cedar Creek Institute in Hastings, Michigan, are some of the few scientists working on the issue. She is trying to develop a long-term dataset focused on the eastern massasauga rattlesnakes. The University of Illinois is also working on treatments for infected snakes. At this moment, the problem seems to be concentrated in the US, but cases of SFD have also been reported in snakes in captivity in England, Germany, and Australia, Kolby said.

“I’m concerned about spillover and introduction to other countries if the United States might be the point source,” he said. “I think that deserves more attention from other countries, too.”

Snakes play an important role in ecosystems, basically serving as nature’s pest control. Most snakes are middle-order predators, which means that they eat other creatures, but they too can be eaten by higher-order predators. Having these creatures which can be both predators and prey gives ecosystems stability and resilience.