Tag Archives: danger

Unhatched birds communicate with each other by vibrating shells

Developed but unhatched birds can not only pick up signals from their parents — they can also communicate with their (also unhatched) siblings by vibrating their shells.

Inside the eggs, gull embryos hear, and respond to, warning calls from adult gulls.

We humans are spoiled in many ways. We’re completely dependent on our parents for years, it takes us a long time to learn how to walk, and in most parts of the world, we rarely have to provide for ourselves. Other creatures don’t have these luxuries — they need to be prepared for danger as quickly as possible.

When danger lurks, most birds produce a distinctive warning sound. For gulls, it’s a specific “ha-ha-ha” sound. Chicks pick up on this signal and are alerted of the looming danger. But even before chicks are hatched, they can still pick up the danger.

A pair of researchers with Universidad de Vigo in Spain found that unhatched chicks can pick up the danger signal and vibrate their shells, transmitting the message to their less-developed siblings.

“We were very surprised,” said Jose Noguera, the lead author of the study from the Animal Ecology Group at the University of Vigo, Spain. “We were aware that bird embryos were able to produce egg vibrations, [but they vibrated] even more than we expected.”

This is not the first time embryonic communication has been studied. Previous research has shown that embryonic birds, amphibians, reptiles, and even insects receive sensory information that helps them prepare for the harsh realities of the real world. Being aware of these dangers and sharing this information with nestmates can help chicks adapt to real situations more quickly, boosting the family’s chances of survival.

The team also found that there are significant behavioral changes associated with this pre-hatching behavior.

In order to reach this conclusion, the team collected 90 yellow-legged gull eggs from Sálvora Island, a large breeding region off the coast of northern Spain. They sorted them into nests of three. Six days before hatching, two out of the three nest eggs were removed from the nest and then exposed to either a recording of a predator alarm or white noise. The third group was not exposed to any sounds.

The birds exposed to alarm calls vibrated in response. When they were reunited with the egg that was not exposed to any sounds, this egg also mimicked the vibrating sounds. The eggs also underwent genetic chances known to delay hatch time, as a response to looming danger, and had an increase in the production of stress hormones, which makes birds more aware of their surroundings after hatching. Birds that were exposed to alarm sounds were quicker to run and hide after hatching.

Researchers are still unsure how the embryos produce and understand these signals, but it’s an absolutely remarkable communication system, which may be much more widespread than it was previously realized.

The findings are published in the journal Nature Ecology and Evolution.

Credit: Scott Hughes/Flickr.

Meet the deadliest tree in the world. It’s so dangerous you could die just by standing underneath it

Credit: Scott Hughes/Flickr.

Credit: Scott Hughes/Flickr.

A vacation on a sunny island in the Caribbean could take a turn for the worse if you’re unfortunate enough to come across the manchineel. No, it’s not some drug trafficking gang nor some venomous creature. It’s a tree whose green fruits look a lot like crabapples. Munch them and you’ll get diarrhea and stomach burns faster than Eve got kicked out of Eden. Eat enough of the toxic fruit and you’ll die. The tree is so dangerous even standing beneath it on a rainy day could be fatal as the tree’s bark is laced with water soluble toxins.

This is where Snow White’s stepmother sources her goods

Locals where the manchineel tree (Hippomane mancinella) is native — places like South Florida, the Caribbean, Central American, and northern South America — have learned to keep away from it. They even gave it an ominous name in Spanish, arbol de la muerte, so people know they shouldn’t mess with it, which literally translates into “tree of death.”

The manchineel's fruits look like green apples which is why it's earned the name of 'little apple of death'. Credit: Photo: ason Hollinger/flickr.

The manchineel’s fruits look like green apples which is why it’s earned the name of ‘little apple of death’. Credit: Photo: ason Hollinger/flickr.

If you’re strolling through some of the paradisiac places where the manchineel grows, you should likely see the trees marked with some danger signs or big painted red crosses as captioned above. Some trees may elude markings, though, which is why every year a select few get poisoned. It happened to Nicola Strickland and her friends in 1999 while vacationing in the Carribean. Attracted by colorful green fruits which looked like small apples, Strickland and gang took a few bites of the fruit. Not too long after their throats tightened to the point they could barely swallow anymore.

No one died that fateful day, though, since the group was lucky enough to ingest only a few bites. Strickland, who is a radiologist, published her experience in The British Medical Journal.

“I rashly took a bite from this fruit and found it pleasantly sweet. My friend also partook (at my suggestion). Moments later we noticed a strange peppery feeling in our mouths, which gradually progressed to a burning, tearing sensation and tightness of the throat. The symptoms worsened over a couple of hours until we could barely swallow solid food because of the excruciating pain and the feeling of a huge obstructing pharyngeal lump. Sadly, the pain was exacerbated by most alcoholic beverages, although mildly appeased by pina coladas, but more so by milk alone,” she wrote.

“Over the next eight hours our oral symptoms slowly began to subside, but our cervical lymph nodes became very tender and easily palpable. Recounting our experience to the locals elicited frank horror and incredulity, such was the fruit’s poisonous reputation.”

The medical problems are caused by the milky sap that oozes out of the tree. When coming in contact with the skin, it causes blistering, burns, and inflammation. Burned manchineel wood could also cause problems if the smoke gets in the eyes. According to a 1984 study, tigliane phorbol esters seem to be toxic compounds that cause these symptoms.

While the esters are found in high concentration in the green fruits, the whole tree packs the toxins — bark, leaves, fruits. Even if you don’t touch the tree itself, you run at risk of getting burned by the caustic esters if these are transported on your skin somehow, such as when it rains. In fact, this is how Calusa native North American fighters from Florida won against conquistador Juan Ponce de Leon and his expedition when they tried to conquer the peninsula in the 16th century. The natives made poisoned arrows out of the manchineel sap and one such arrow struck de Leon in the thigh. He retreated in Cuba where he later died from the toxins. Legend has it, also, that the natives would torture prisoners by placing them beneath the tree when it rains. The highly caustic water blinded the prisoners and caused terrible pain.

Seeing how the manchineel is so dangerous, why don’t we just destroy it? Ethics aside, the manchineel tree is actually useful. It provides windbreaking and protection against coastal erosion on Central American beaches. Carpenters have been using its prized wood for centuries to make furniture out of it, being careful to cut the bark and leave the wood in the sun until the toxins are neutralized. It also has medical properties, as it can treat edema in gum form, while dried fruits have been used as a diuretic — of course, you have to be very careful about it.

From an evolutionary perspective, it’s clear the manchineel adapted this trait for protection but it’s not clear what could have tempted it to go to such extreme. Being so poisonous, it can’t rely on animals to spread its seeds, which is a disadvantage, but it seems to make up for it by leaving in coastal areas where the wind can do the job.

It’s not so often that you hear about a killer tree, not unless you count crashing a car into one. We’re used to seeing trees as benign but the manchineel proves there’s more to it. So, next time you vacation in an exotic location, be sure to get all your shots and, most importantly, read about dangerous local fauna.

 

 

How your brain distinguishes safety from danger

Columbia University researchers have successfully identified the cellular network that allows mice to remember which environments are safe and which are dangerous. The study also looks into what happens when these neurons are tampered with, offering insight into how conditions such as PTDS, panic attacks and anxiety disorders can be treated.

This is an image showing LRIP inhibitory neurons (in green) extending from the entorhinal cortex (lower right) into the hippocampus. LRIPs have been found to be part of a sophisticated mechanism that is critical to the formation of contextual memories.
Image via sciencedaily

The brain’s capacity to learn and encode memories are two cornerstone tools for any animal’s survival. Contextual memories (those that form during particular experiences) form the basis for appropriate fear responses in dangerous settings and help avoiding such situations in the future.

Just remembering that a particular setting or series of events ultimately led to danger and estimating whether an environment is safe or poses a threat are two very different things however. Earlier research found that contextual memories form and remain encoded in two separate but highly interconnected brain areas — the hippocampus and the entorhinal cortex — involved in memory and navigation.

Two of the connections between these areas have well documented roles and ways of functioning, but the third such bundle of neurons had scientists puzzling over what ts role actually was.

“Neurons in the entorhinal cortex wind their way into the hippocampus via two distinct routes, or pathways,” explained PhD Jayeeta Basu, first author of the paper.

“It is thought that contextual memories are formed when these two pathways became activated as part of a carefully timed sequence. But a few years ago, scientists discovered a third pathway that linked the two regions whose purpose was unknown.”

There are two “flavors” of neurons; around 80% of them are excitatory meaning they carry signals over long distances in the brain, often across whole brain regions, with the other 20% being inhibitory — they function locally to slow or halt excitatory activity. What was so unusual about the neurons in this recently discovered third pathway was that they acted across a relatively long distance, but were also inhibitory. So scientists called them long-range inhibitory projections, or LRIPs.

This new study aimed to investigate the role LRIPs played in the processes of learning and memory formation. To this end, the team first temporarily inhibited their activity in mice, then placed the animals in a room where they were subjected to a brief electric shock delivered through the floor. When returned to the room 24 hours later, the mice showed signs of fear, indicating that they remembered the electric shock. The scientists concluded that LRIPs weren’t involved in the formation of “fearful memories.”

When placed in a completely different room however, the mice again showed signs of fear, suggesting that their fear of the electric shock generalized from the initial room to a different context. Control-group mice showed signs of fear when placed in the initial chamber but not in the second one, revealing the role of LRIPs in distinguishing between dangerous or benign environments.

Brain imaging techniques and electrical recordings from unaltered mice revealed the role of the connection in much more precise detail. When a stimulus such as sound, light or footshock activates the LRIPs, neurons fire an inhibitory signal from the entorhinal cortex to the hippocampus. This LRIP signal silences a set of inhibitory cells in the hippocampus, allowing other neurons to activate and ultimately generating a memory.

It’s a bit confusing but this series of signals is only a part of a larger and even more convoluted gating mechanism, evidenced by a short 20-millisecnd delay between the activation of the LRIPs and the arrival of inhibitory signals to the hippocampus.

“This brief delay enables the electrical signals to flow into the hippocampus in an elegant, precisely timed sequence, which is ultimately what allows the memory to form and be stored with the appropriate specificity so that it can be recalled accurately,” said senior author Dr. Siegelbaum.

“Without this delay, fearful memories lack specificity and accuracy, preventing the brain from appropriately distinguishing danger from safety.”

“The implications of these findings for the human brain, while preliminary, are intriguing,” said PhD co-author Attila Losonczy.

“The study suggests that any alterations in these pathways activity–particularly a disruption of the timed delay–may contribute to pathological forms of fear response, such as posttraumatic stress, anxiety, or panic disorders.”

The paper, titled “Gating of hippocampal activity, plasticity, and memory by entorhinal cortex long-range inhibition” is available online here.

 

How NASA might save the world from killer asteroids

It almost looks like a sci-fi movie; in a small, crammed room at the Goddard Space Flight Center, a group of brilliant NASA researchers are discussing ways to protect our planet from dangerous asteroids. But this is not a movie, it’s reality – and it’s happening now. So how big is the threat from asteroids? Spoiler alert: you shouldn’t waste any sleep on it.

This diagram was revealed after astronomers reported a 1km space rock called Icarus which “brushed” past Earth this week. Every single line is the orbit of an asteroid large enough to cause major damage to the Earth and threaten all life on it. NASA also stated that many more asteroids exist but aren’t included in this diagram, either because they haven’t been discovered yet, or because their orbit hasn’t been mapped.

Eric Edelman, producer of the Slooh telescope live internet channel said:

“This is a startling image. These are the potentially hazardous asteroids that surround us and we are keeping an eye on to make sure they do not hit us. This is a really amazing figure to see that many lines that we are keeping our eye on.”

Astronomer Bob Berman also commented on the limitations of this image.

“Absolutely, I wish we could see it in 3D as we can’t see how many of them cross our path in each dimension, but if it is in this diagram it means they can cross our path and can hit us and that is a lot of them. If a half mile object like icarus hit it would be a very band day for Earth indeed.” He also said the orbits were unpredictable, adding: “They do not have nice round orbit like our own planet, some go in then come out.”

All in all, according to Jason Kessler, NASA’s director of the Grand Challenge, we know of 12,706 Near Earth Objects (NEOs) — or asteroids — that could come close to Earth.

“Of those 1,593 are potentially hazardous, meaning they might cross earth’s path,” he said.

So why then, shouldn’t we worry?

NASA religiously monitors lose asteroid fly-bys but does not believe we are in danger of actually being hit by one of them for at least a few hundreds of years. Also, even if one asteroid was set to collide with Earth, there are things we could do. Astronomers are actually considering trapping an asteroid and bringing it safely to Earth, which is much more complicated than simply deflecting it.

“We have the technologies to be able to do it, and the same technology is needed to capture asteroids,” said Ben Reed, who heads up the team that is developing NASA’s Asteroid Robotic Redirect Mission.

He and his team are working on an asteroid lander which could be programmed to change its course and follow rogue asteroids. The lander could use thrusters or its own gravitational pull to make slight changes to the asteroid’s orbit – enough to deflect it from a dangerous trajectory. The same technology could be used to extract a piece from the asteroid and bring it back home for study.

Reed then went on to discuss potential hazards, and expressed a reassuring opinion:

“We have the technologies to mitigate any potential threats,” he said. Kessler said though the data sounds menacing, “Nothing we know of is threatening Earth right now.”