Tag Archives: shrimp

Water plastic cup.

Plastic is “everywhere” in the ocean, including its deepest trenches — “There’s no good aspect to this,” researchers say

Plastic fragments have been found in the digestive tracts of animals in the deepest parts of the oceans, a new paper reports. The findings illustrate how incredibly wide humanity’s impact on the planet has become.

Water plastic cup.

Image via Pixabay.

We really do live in a plastic world, as that old song used to go. Humanity produces around 350 million metric tones of plastics each year and, sadly, a large chunk of that is meant to be used and immediately discarded. As such, we’ve managed to build up quite a pile of plastic trash — at least five trillion pieces of it are floating around in the world’s oceans.

Polymer diet

All this plastic eventually finds its way into the bellies of fish and other ocean wildlife. Most studies up to now focused on near-surface plastic contamination in wildlife, and all have found it to be widespread in fish, turtles, whales, and sea birds.

A new study, however, aimed to look at the bottom of the oceans. The team analyzed shrimp from six of the world’s deepest ocean trenches looking for signs of plastic ingestion — and their findings are Not Good. In the Mariana Trench, the deepest spot on Earth, 100% of the studied animals had plastic fibers in their guts, the team reports.

“Half of me was expecting to find something but that is huge,” said lead author Alan Jamieson from Newcastle University’s School of Natural and Environmental Sciences.

Jamieson and his team’s day job is finding new species hidden in the depths. But a decade’s worth of abyssal expeditions left them with a sizeable collection of shrimp specimens from between 6,000-11,000 meters (19,500-36,000 feet) beneath the surface. Curious to know whether plastics sunk down to these animals’ environments, they decided to take a look at the shrimp.

“We are sitting on the deepest dataset in the world, so if we find (plastics) in these, we are done,” Jamieson told AFP.

The team admits they were astonished to see how widespread plastic corruption was at the bottom of the ocean. For example, plastic was found in the digestive systems of animals recovered from the Peru-Chile Trench in the southeast Pacific as well as the Japan Trench — although the two are around 15,000 kilometers (9,300 miles) apart.

“It’s off Japan, off New Zealand, off Peru, and each trench is phenomenally deep,” Jamieson said. “The salient point is that they are consistently found in animals all around the Pacific at extraordinary depths so let’s not waste time. It’s everywhere.”

All in all, 65 of the 90 specimen in the team’s collection (72%) had at least one plastic microparticle in their gut. The team does note that these particles could have been ingested by fish at higher depths and were taken to the bottom of the ocean as the animal died. However, analyses performed on the fibers, most of which seem to be clothing fabrics, showed that they were likely several years old. The team reports that the atomic bonds in the plastic fibers had shifted, unlike what you’d see in a ‘fresh’ plastic mass.

Microplastics are generally dumped directly into the sea, the team writes, via sewers and rivers. They then bunch together into larger bodies and start degrading. As part of this process, bacteria starts moving into the plastic mass’ pores — making it heavier until it eventually sinks. Jamieson puts it more succinctly and in words I wouldn’t be allowed to use, so here’s his take on it:

“So even if not a single fibre were to enter the sea from this point forward, everything that’s in the sea now is going to eventually sink, and once it’s in the deep sea where is the mechanism to get it back?” Jamieson asks.

“We are piling all our crap into the place we know least about.”

Plastic contamination seems to be widespread in the ocean’s deepest areas, and the team cautions that we might unwittingly do a massive amount of damage to bottom-dwellers. In theory, plastics should pass unaffected through an animal’s digestive tract, but the team found they caused blockages in the animals they studied.

“The equivalent would be for you to swallow a 2-metre polypropylene rope and expect that not to have an adverse affect on your health,” Jamieson adds.

“There’s no good aspect to this.”

The paper “Microplastics and synthetic particles ingested by deep-sea amphipods in six of the deepest marine ecosystems on Earth” has been published in the journal Royal Society Open Science.

Cuttlefish can count at least up to five, new study finds

Cuttlefish can count at least up to five, a new study from Taiwan’s National Tsing Hua University found. The team used a single-choice experiment to come to these findings, which makes the cuttlefish “equivalent to infants and primates in terms of number sense.”

It can only count to five because that’s how many seconds it needs to steal your heart.
Image credits Bill Abbott / Flickr.

Cuttlefish belong to the order Sepiida, and are relatives of other invertebrates such as squids, octopuses, or nautiliuses. They have the largest brain-to-body ratio among all invertebrates, eight tiny arms, and employ a specialized pair of tentacles covered in suckers to nab their prey from afar. All their hunting of shrimp and crabs means that cuttlefish need to make constant decisions about which prey to target — so it would make sense for them to be capable of higher cognitive skills such as counting. And here’s where that big brain comes in handy.

Tsang-I Yang and Chuan-Chin Chiao of Taiwan’s National Tsing Hua University hatched Sepia pharaonis eggs in laboratory conditions and waited until the animals were a month old. They wanted to find out if cuttlefish are actually capable of counting, so it was important to give them some time to develop. Then, they started to test the young cephalopods‘ math skills.

Each test consisted of the researchers presenting a cuttlefish waiting in a tank with a two-chambered box made out of clear material. In each of the boxes, the researchers would place a number of tasty shrimp for the cuttlefish. The screen that separated the compartments jutted out towards the animal to force it to choose just one of the two. After the cuttlefish made its decision and swam to either side of the screen, the researchers took the box out of the water — this was done to control how hungry they are and what effect this would have on their choice. The cuttlefish were fed at the end of the testing session.

Cuttlemath 101.
Image credits Yang TI, Chiao CC (2016.)

The duo put one to five shrimp into each box to test how well the animals can count. If there were five shrimp on one side and one in the other, the choice was pretty easy to make. But the team also presented them with a choice between three and two shrimp, or five over four, choices which aren’t easily made without the ability to count.

All in all, 54 cuttlefish were tested. The team reports that unsurprisingly, they had no difficulty picking several shrimp over a single one — but they also aced every other test they were presented with. They were much more likely to pick the side of the box with more shrimp, even when choosing between four and five. They took more time to decide as the ratios between the number of shrimp in the boxes became smaller (such as 5 to 4 vs 2 to 1.) Chiao says this is evidence that the cuttlefish were actually counting the shrimp on each side, rather than judging the quantities at a glance.

The team also ruled out the possibility that the animals were just picking the largest bunch of shrimp they could find — when the team crowded small numbers of shrimp in in tighter cages to make them seem denser, the cuttlefish weren’t fooled. They still picked the side with more shrimp. The researchers also used boxes of dead shrimp to test if the cuttlefish were just going for the liveliest bunch — but here too, they went for the side with more shrimp.

So they can do math, but they aren’t just cold calculating adding machines. They prefer live victims, and when offered a choice between one live shrimp or two dead ones, they chose the first. When choosing between one big, fat, tasty shrimp or two smaller ones, hungry cuttlefish went for the former, while cuttlefish that had already eaten chose the latter. The team believes this may be because while one big shrimp is more tempting, it’s also more difficult to tackle with. Cuttlefish that weren’t particularly hungry simply didn’t think it was worth the risk

Chiao says he wasn’t surprised by the results. Although the experiments stopped at 5 shrimp, he suspects that the animals may be able to count higher.

“We know that [the] cuttlefish has a complex brain and a sophisticated neural system,” he says.

“Cuttlefish have to search for food constantly, so having number sense is important for their life.”

One-year-old babies can judge the difference between 1, 2 or 3 items, but don’t seem to do well above that limit. Rhesus macaques of the same age can reliably count up to 4. So, the authors write, the study “implies that cuttlefish are at least equivalent to infants and primates in terms of number sense.”

The full paper “Number sense and state-dependent valuation in cuttlefish” has been published in the journal Proceedings. Biological sciences / The Royal Society.

Mantis shrimps teach humans how to make a new type of optical material

Some time ago we wrote about the mantis shrimp’s uncanny form of communication: polarized light. Research focusing in on these tiny animals’ chatter will allow us to create a whole new type of polarizer — an optical device widely employed in modern cameras, DVD players, even sunglasses.

Mantis shrimp are probably best known for the dazzling colors that adorn their shells. The second thing they’re best known for is their tendency to violently murder anything they come into contact with. Using two frontal appendages that can move as fast as a bullet, the shrimp hunts for crabs, oysters, octopi, anything really, blasting them apart with an insanely powerful 1,5 kilo Newtons of force (337.21 lbs of force.)

Look at him. He just knows he’s the baddest shrimp in this pond.
Image via wikipedia

But why? And how did they come by their weapons? What is the mantis shrimp’s secret? Well nobody knows, because they communicate using a process so secretive most other species don’t even realize it’s happening.

The shrimp rely on light polarization to keep their conversations private. They have evolved reflectors that allow them to control the polarization of their visual signals, a property of light that most other species aren’t able to pick up on.

In an effort to crack their code, researchers from the Ecology of Vision Group (based in the University of Bristol’s School of Biological Sciences) have studied the shrimps and discovered they employ a polarizing structure radically different from anything that humans have ever seen or developed.

The team’s analysis, coupled with computer modelling revealed that the mantis shrimp’s polarizers manipulate light across it’s structure rather than through its depth — as our polarizers do. This mechanism allows the animal to have small, microscopically thin and dynamic optical structures that still produce big, bright and colourful polarized signals.

“When it comes to developing a new way to make polarizers, nature has come up with optical solutions we haven’t yet thought of,” said Dr Nicholas Roberts from the School of Biological Sciences.

“Industries working on optical technologies will be interested in this new solution mantis shrimp have found to create a polarizer as new ways for humans to use and control light are developed.”

The full paper, titled ‘A shape-anisotropic reflective polarizer in a stomatopod crustacean’ is available online here.

Shrimps communicate using a secret, polarized light language

An University of Queensland study of mantis shrimp discovered a new form of light communication employed by the animals, the findings having potential applications in satellite remote sensing, biomedical imaging, cancer detection, and computer data storage.

Dr Yakir Gagnon, Professor Justin Marshall and their colleagues at the Queensland Brain Institute previously found that mantis shrimp (Gonodactylaceus falcatus) can sense and reflect circular polarizing light, an ability extremely rare in nature. Until now, no-one has known what they use it for. The study follows up on that research and shows how shrimp use circular polarization to covertly communicate their presence to aggressive competitors.

This is my rock!
Image via wikimedia

“In birds, colour is what we’re familiar with and in the ocean, reef fish display with colour – this is a form of communication we understand. What we’re now discovering is there’s a completely new language of communication,” said Professor Marshall.

Where linear polarized light travels in only one plane, circular polarized light travels in a clockwise or anti-clockwise spiral. The human eye can’t see polarized light, but special lenses — often found in sunglasses — make it visible. It’s also invisible to most other animals, and the shrimp use this to their advantage:

“We’ve determined that a mantis shrimp displays circular polarised patterns on its body, particularly on its legs, head and heavily armoured tail,” said Professor Marshall. “These are the regions most visible when it curls up during conflict.”

“These shrimps live in holes in the reef,” he added. “They like to hide away; they’re secretive and don’t like to be in the open.”

They are also “very violent”, Professor Marshall goes on to explain:

“They’re nasty animals. They’re called mantis shrimps because they have a pair of legs at the front used to catch their prey, but 40 times faster than the preying mantis. They can pack a punch like a .22 calibre bullet and can break aquarium glass. Other mantis shrimp know this and are very cautious on the reef.”

And this aggression is what the team used to test the animals. For the study, the researchers put a mantis shrimp in a water tank, providing them with two burrows they could chose from for shelter: one reflected unpolarised light and the other, circular polarized light. The shrimps made a beeline for the unpolarized burrow in 68% of tests, suggesting that they viewed the other hiding spot as being already occupied.

“If you essentially label holes with circular polarising light, by shining circular polarising light out of them, shrimps won’t go near it,” said Professor Marshall. “They know – or they think they know – there’s another shrimp there.

Cameras equipped with circular polarizing sensors, similar to the shrimp’s sensory organs, may detect cancer cells long before the human eye can see them.

“Cancerous cells do not reflect polarised light, in particular circular polarising light, in the same way as healthy cells,” he added.

But they’re not the only ones that see it

Professor Marshall also published another study in this number of the journal, showing that linear polarized light is used as a form of communication by fiddler crabs, Uca stenodactylus. They live on mudflats, a very reflective environment, and use the the amount of polarisation reflected by objects, the researchers found, to navigate through and react to their environment.

“It appears that fiddler crabs have evolved inbuilt sunglasses, in the same way as we use polarising sunglasses to reduce glare,” Professor Marshall said.

Fiddler crab.
Image via wikimedia

Fiddler crabs react to ground-based objects based on how much polarized light they reflected, moving in either a forward mating stance, or retreating back into their holes, at varying speeds.

“These animals are dealing in a currency of polarisation that is completely invisible to humans,” Professor Marshall said. “It’s all part of this new story on the language of polarisation.”

Both the mantis shrimp study and the fiddler crab study are available online in the journal Current Biology.

Northern shrimp hauled aboard a shrimp boat. Credit: Wikimedia

Shrimps become less tastier as a result of climate change

The effects of climate change on food stock quality is well documented, yet a new study suggests that climate change might not only affect survival rates of marine life, but also how it tastes too. The findings came after an international team of researchers sought to see how high water acidity affects the sensory quality of shrimp.

Northern shrimp hauled aboard a shrimp boat. Credit: Wikimedia

Northern shrimp hauled aboard a shrimp boat. Credit: Wikimedia

Carbon is stored not only in trees, but also in the world’s oceans and sea which act like huge carbon sinks. As more and more carbon is being absorbed, this causes the water to become more acidic, a process called ocean acidification. Marine animals  interact in complex food webs that may be disrupted by ocean acidification due to losses in key species that will have trouble creating calcium carbonate shells in acidified waters. Some species of calcifying plankton that are threatened by ocean acidification form the base of marine food chains and are important sources of prey to many larger organisms. With coral and plankton gone, most marine species will follow, thus acidification is a huge concern. But if you’re not that interested in the fate of marine life, maybe you’d be more considerate of how it tastes.

The researchers put hundreds of northern shrimps (Pandalus borealis) into tanks that mimic a projected 2100 ocean acidification level of pH 7.5, while a control group was put in tanks of pH 8.0, the current average level in the waters. In addition, the water was heated to 11 degrees Centigrade, or roughly the extreme of the shrimps’ temperature tolerance, so that the animals would be more stressed and make acidification stand out more. After three weeks, the shrimps were put out of the tanks and served to 30 connoisseurs for a taste test.

Shrimp from less acidic waters were 3.4 times as likely to be judged the tastiest, while those from more acidic waters were 2.6 times as likely to be rated the worst tasting, according to the paper published in the Journal of Shellfish Research. Not to be neglected is that decreased pH increased mortality significantly, by 63%. Does this mean that the shrimp industry is doomed? It’s hard to tell, but what the study shows is that the effects of climate change extend well beyond food supply, but also quality. I’ve yet to find something similar, but it may be likely that the same might be said about other marine food stocks, like tuna.

Regarding terrestrial food, a University of California, Davis study found that  rising CO2 levels are inhibits plants’ ability to assimilate nitrates into nutrients, altering their quality for the worse. Thus, it’s expected that crops in the future will contain less nutrients than they do today.

 

The punching mantis shrimp is one of the meanest sea dweller. Photo: Carlos Puma

Claws of meanest crustacean inspire supermaterial design

The punching mantis shrimp is one of the meanest sea dweller. Photo: Carlos Puma

The punching mantis shrimp is one of the meanest sea dweller. Photo: Carlos Puma

As the night covers the tropics, odd clicky sounds run about much to the annoyance of sailors stationed in harbors. These sounds are made by the punching mantis shrimp, a very small crustacean which doesn’t seem that much threatening but who definitely lives up to its name. Its claws are so powerful that it can clamp with a force up to 1,000 times its own weight, shattering unsuspecting prey, other punching mantises and just about anyone or anything that gets in its way. This is a bad shrimp, no doubt, yet the things scientists can learn from it are nothing short of amazing. A team found, for instance, that they could design an ultra strong composite material based on how the punching mantis shrimp’s claw are made, with potential applications in aerospace, auto industry or defense.

You don’t want this shrimp on your dinner table

At 4 to 6 in (10 to 15 cm) long, you might not give a second thought to the punching mantis shrimp, but it really is a sucker puncher. First thing you notice is its club-like claws, but what’s amazing is how hard it can close them. Close observations show that its claws cock back like a pistol hammer and as it snaps closed, it accelerates faster than a .22-caliber bullet, generating a force more than 1,000 times the shrimp’s own weight. So if it pinched your finger, imagine something like 200 lb (91 kg) instantly pressing over it. If you’re a punching mantis shrimp enthusiast, then you know how hard these fellas are hard to keep since they regularly break aquariums and owners need to keep them in special tanks.

At this kind of acceleration, the energy released by the shrimp’s claws is enormous – enough to literally boil water at a temperature of 4,000⁰ C (7,200 ⁰ F). Also, the released energy triggers a shock wave that it stuns or kills small prey at a distance. By now, I take it, you’re convinced the punching mantis shrimp is one bad mother. A natural question arises, however: how can this tiny animal withstand these enormous energies in its claws?

Electron microscope imaging shows the mantis shrimp's cuticles are aligned in a spiral fashion. Photo: University of California

Electron microscope imaging shows the mantis shrimp’s cuticles are aligned in a spiral fashion. Photo: University of California

The same question puzzled a team of researchers at University of California who saw this an opportunity to maybe devise a new material based on how the shrimp’s claws are grown. Carefully studying it, researchers found the claw’s covering, called the cuticle, is made up of several layers, the innermost of which is the endocuticle. Remarkably, these sections are comprised of tiny mineralized fibers aligned in a spiral fashion, as each layer is offset by a small angle from the next.

Using  carbon fiber-epoxy composites, the researchers designed a spiral of their own with fibers set at three different angles ranging from 10 to 25 degrees to the previous layer. They then built two control structures made from the same material: one in a simple one-way spiral and the other with each layer placed at a quarter turn to the previous one.

Shock, tension and compression tests showed that control materials behaved badly, with the one way spiral failing completing and the other becoming severely punctured or damaged. The material designed based on the punching mantis shrimp, however, only took up 20% of the damage as that of the quarter turn version. The shrimp’s spiral design allows for a  more even dispersion of energy, keeping shock from concentration in a single spot, thus avoiding structural failure.

The findings, published in the journal Acta Biomaterialia, suggest that a multitude of everyday applications could be improved with materials designed like the shrimp’s claws, from aerospace, to automobiles, to body armor. It remains to be seen how easy manufacturing can be integrated to make such compounds cheap enough for mass production. Yet again, however, studies such as this show that scientists need not look too far inspiration to solve the challenges they’re met with. Imitation can be an art.

 

 

NASA is stunned to find life beneath 183 meters of Antarctic ice

At nearly 200 meters below the ice, there is no light, the temperature is way below 0 degrees, and scientists were expecting to find nothing more than a handful of microbes – and for good reason. So it’s easy to understand why they were so surprised to find not a single (evolved) life form, but actually two such creatures.

Antarctica Sea Life

The National Aeronautics and Space Administration lowered the camera, in an attempt to look deep in the underbelly of Antarctica’s ice; not long after that, a shrimp-like creature swam by and then “landed” on the cable. Scientists also picked up a tentacle that they believe can only come from a jellyfish – a pretty big one too.

“We were operating on the presumption that nothing’s there,” said NASA ice scientist Robert Bindschadler, who will be presenting the initial findings and a video at an American Geophysical Union meeting Wednesday. “It was a shrimp you’d enjoy having on your plate. We were just gaga over it,” he said of the 3-inch-long (76-millimeter, orange critter starring in their two-minute video.

The video forces experts to rethink what they previously believed about where evolved animals can survive in extreme environments; if they can live in this freezing underwater environment, why not on Europa, the frozen moon of Jupiter, or other such places?

“This is a first for the sub-glacial environment with that level of sophistication,” Ellis-Evans said. He said there have been findings somewhat similar, showing complex life in retreating ice shelves, but nothing quite directly under the ice like this.