How mantis shrimp find their way home


This 29 May 2019 video says about itself:

Mantis Shrimp Packs a Punch | Predator in Paradise

Armed with the most sophisticated vision and fastest strike of any predator on Earth, the mantis shrimp is an unexpected threat.

From the University of Maryland Baltimore County in the USA:

How do mantis shrimp find their way home?

April 9, 2020

Summary: New research indicates mantis shrimp use path integration to find their way back to their burrows after leaving to seek food or mates. That means they can track their distance and direction from their starting point. A series of creative experiments revealed that to do that, they rely on a hierarchy of cues from the sun, polarized light patterns, and their internal senses.

Mantis shrimps have earned fame for their powerful punching limbs, incredibly unusual eyes, and vivid exoskeletons. And, it turns out, they’re also really good at finding their way home. Through a series of painstaking experiments with these often-uncooperative creatures, Rickesh Patel has produced new findings on mantis shrimp navigation, published this week in Current Biology.

Patel, a Ph.D. candidate in biological sciences at UMBC, found that the species of mantis shrimp he investigated relies on the sun, patterns in polarized light, and internal cues — in that order — to navigate directly back to their non-descript burrows. These straight-line returns often follow forays that meander and zig-zag as the shrimp looks for a meal or a mate. The ability to get home quickly comes in handy when seeking shelter in the presence of predators, or a perceived one, as Patel noted on his first research fieldwork expedition.

After his first year at UMBC, Patel traveled with Tom Cronin’s lab to Lizard Island in the Great Barrier Reef to collect mantis shrimp for study. “As soon as they notice you, they’ll turn around and zip straight to some sort of shelter,” Patel says. Like a true scientist, “That got me wondering how they go about finding their way home.”

A crucial starting point

Scientists have written a great deal on navigation in other species — primarily bees, ants, and mice — but Patel’s is the first work on navigation in mantis shrimp.

First, Patel had to find a behavior he could work with to test ideas about how mantis shrimp navigate. So he created a small arena with an artificial shrimp burrow buried in sand. He placed the shrimp in the arena, and to his delight, the mantis shrimp was happy to occupy the small section of PVC pipe. Then he placed a piece of food at a distance from the burrow. He watched as the shrimp left its burrow, meandered until it found the food, and then returned to its burrow in a fairly straight line.

From those initial observations, Patel hypothesized that mantis shrimps use a process called path integration to find their way home. In other words, they are somehow able to track both their distance and direction from their burrow.

“That was probably the most exciting part of the experiments for me, because I knew I had a really robust behavior that I could work with,” Patel says. “Everything I did really extended from that initial point.”

Sunshine surprise

After that first discovery, the challenging work began, to figure out what cues the animals were using to determine the path home.

Patel built eight much larger arenas, each about 1.5 meters in diameter, to run his experiments. The first question he asked was whether the shrimp were using internal or external cues to go home.

To test that, Patel created a setup that rotated the animal 180 degrees as it retrieved the food. If the shrimp was using external cues to remember its distance and direction from home, it would still head in the right direction. If it was using internal cues, based on the orientation of its own body, it would head in the opposite direction. In the first round of trials, the animals consistently headed in the exact opposite direction.

“That was really cool, but it didn’t make a lot of sense,” Patel says, “because an internal compass is going to be a lot less accurate than something that is tied to the environment.” Then it hit him: “We just happened to have a really overcast week when I did these experiments, so I waited until we had a clear day, and then every time, they went right back home.”

Putting together the puzzle

Patel realized that his experiment perfectly demonstrated the hierarchy of cues used by the animals. They used external cues first, but when those weren’t available, they used internal cues.

That was the beginning of a long series of creative experiments that further teased out how these animals navigate. When Patel used a mirror to trick the animals into thinking the sun was coming from the opposite direction, they went the wrong way. This indicated they use the sun as a primary cue. When it was cloudy but not totally dark, they used polarization patterns in light, which are still detectable when it’s overcast. And when the sky was completely covered, they reverted to their internal navigation system.

A varied skillset

For Patel, creating the experimental arenas — essentially, the shrimp obstacle course — was almost as fun as getting the results. “That’s something I really enjoy — building things, creating things,” he shares. Patel studied art and biology as an undergraduate at California State University, Long Beach. “I think those skills lent me a hand in designing my experiments.”

Other skills Patel needed were patience and perseverance. “The animals will only behave maybe once a day, so if you scare the animal, you’ve lost that day,” he says.

For example, one of the experiments involved putting the animals on a track that pulled them to a new position, and seeing where they headed from there. “If the track is too jerky or goes too fast, they get scared and just don’t behave,” Patel says. “So I had to design the experiment so that it was so gentle they didn’t realize they were being moved.”

New questions

All of Patel’s patience has paid off with new findings that open up an array of future questions to answer. While path integration is well-documented in other species, mantis shrimp are the first to demonstrate the technique underwater. Looking up at the sky through water is a very different view than doing so through air, so Patel is curious how the animals’ process is different from other species.

Patel is also ultimately interested in the neural basis of navigation behavior, but “before you can investigate what’s happening in the brain, you have to understand what the animal’s doing,” he says. “So that’s why I really focused on the behavior work, to figure out what the animal is doing and what kind of stimuli are appropriate to show the animal that we can use to investigate its neurology.”

So far, other work has demonstrated that a brain region called the central complex has uncanny similarities between insects and mantis shrimps. This is especially interesting considering how far apart bees and shrimp are on the tree of life. The central complex is known to contribute to navigation in bees, so Patel is intrigued to learn more about its function in mantis shrimp. Alice Chou, another graduate student in the Cronin lab, is also investigating the brain structures of mantis shrimp.

Cuban land crabs’ mass migration, videos


This 20 March 2020 video, recorded in Cuba, says about itself:

Swarm of Crab Mothers Cross Traffic to Lay Thousands of Eggs

An army of red land crabs migrates miles as some mothers prepare to lay up to 80,000 eggs apiece.

I saw migrating crabs in Cuba.

This May 2017 video says about itself:

Cuba: Crabs invade Bay of Pigs showing US how it’s done

Millions of crabs have invaded Cuba’s Bay of Pigs (Playa Giron), as shown by footage filmed on Wednesday.

The red, yellow and black crabs are undertaking their annual spring migration from the forest to the sea, where they aim to release their eggs.

Christmas Island crab steals expensive camera


This video says about itself:

Thursday, 12 March 2020

Robber crab‘ steals expensive research equipment

Western Sydney University Doctor of Philosophy candidate Annabel Dorrestein had been using the expensive camera as part of her research project on Christmas Island.

Dutch Ms Dorrestein used the camera for research on Christmas Island flying-foxes (Pteropus melanotus natalis).

Shrimps’, insects’ brains are similar


This 9 October 2017 video says about itself:

Insect like Brain Region Found in Crustacean Brain

Mushroom bodies are the iconic learning and memory centers of insects. No previously described crustacean possesses a mushroom body as defined by strict morphological criteria although crustacean centers called hemiellipsoid bodies, which serve functions in sensory integration, have been viewed as evolutionarily convergent with mushroom bodies. Here, using key identifiers to characterize neural arrangements, we demonstrate insect-like mushroom bodies in stomatopod crustaceans (mantis shrimps).

More than any other crustacean taxon, mantis shrimps display sophisticated behaviors relating to predation, spatial memory, and visual recognition comparable to those of insects. However, neuroanatomy-based cladistics suggesting close phylogenetic proximity of insects and stomatopod crustaceans conflicts with genomic evidence showing hexapods closely related to simple crustaceans called remipedes. We discuss whether corresponding anatomical phenotypes described here reflect the cerebral morphology of a common ancestor of Pancrustacea or an extraordinary example of convergent evolution.

From the University of Arizona in the USA:

The brains of shrimps and insects are more alike than we thought

March 3, 2020

New research shows that crustaceans such as shrimps, lobsters and crabs have more in common with their insect relatives than previously thought — when it comes to the structure of their brains.

Both insects and crustaceans possess mushroom-shaped brain structures known in insects to be required for learning, memory and possibly negotiating complex, three-dimensional environments, according to the study, led by University of Arizona neuroscientist Nicholas Strausfeld.

The research, published in the open-access journal eLife, challenges a widely held belief in the scientific community that these brain structures — called “mushroom bodies” — are conspicuously absent from crustacean brains.

In 2017, Strausfeld’s team reported a detailed analysis of mushroom bodies discovered in the brain of the mantis shrimp, Squilla mantis. In the current paper, the group provides evidence that neuro-anatomical features that define mushroom bodies — at one time thought to be an evolutionary feature proprietary to insects — are present across crustaceans, a group that includes more than 50,000 species.

Crustaceans and insects are known to descend from a common ancestor that lived about a half billion years ago and has long been extinct.

“The mushroom body is an incredibly ancient, fundamental brain structure,” said Strausfeld, Regents Professor of neuroscience and director of the University of Arizona’s Center for Insect Science. “When you look across the arthropods as a group, it’s everywhere.”

In addition to insects and crustaceans, other arthropods include arachnids, such as scorpions and spiders, and myriapods, such as millipedes and centipedes.

Characterized by their external skeletons and jointed appendages, arthropods make up the most species-rich group of animals known, populating almost every conceivable habitat. About 480 million years ago, the arthropod family tree split, with one lineage producing the arachnids and another the mandibulates. The second group split again to provide the lineage leading to modern crustaceans, including shrimps and lobsters, and six-legged creatures, including insects — the most diverse group of arthropods living today.

Decades of research have untangled arthropods’ evolutionary relationships using morphological, molecular and genetic data, as well as evidence from the structure of their brains.

Mushroom bodies in the brain have been shown to be the central processing units where sensory input converges. Vision, smell, taste and touch all are integrated here, as studies on honeybees have shown. Arranged in pairs, each mushroom body consists of a column-like portion, called the lobe, capped by a dome-like structure, called the calyx, where neurons that relay information sent from the animal’s sensory organs converge. This information is passed to neurons that supply thousands of intersecting nerve fibers in the lobes that are essential for computing and storing memories.

Recent research by other scientists has also shown that those circuits interact with other brain centers in strengthening or reducing the importance of a recollection as the animal gathers experiences from its environment.

“The mushroom bodies contain networks where interesting associations are being made that give rise to memory,” Strausfeld said. “It’s how the animal makes sense of its environment.”

A more evolutionarily “modern” group of crustaceans called Reptantia, which includes many lobsters and crabs, do indeed appear to have brain centers that don’t look at all like the insect mushroom body. This, the authors suggest, helped create the misconception crustaceans lack the structures altogether.

Brain analysis of crustaceans has revealed that while the mushroom bodies found in crustaceans appear more diverse than those of insects, their defining neuroanatomical and molecular elements are all there.

Using crustacean brain samples, the researchers applied tagged antibodies that act like probes, homing in on and highlighting proteins that have been shown to be essential for learning and memory in fruit flies. Sensitive tissue-staining techniques further enabled visualization of mushroom bodies’ intricate architecture.

“We know of several proteins that are necessary for the establishment of learning and memory in fruit flies,” Strausfeld said, “and if you use antibodies that detect those proteins across insect species, the mushroom bodies light up every time.”

Using this method revealed that the same proteins are not unique to insects; they show up in the brains of other arthropods, including centipedes, millipedes and some arachnids. Even vertebrates, including humans, have them in a brain structure called the hippocampus, a known center for memory and learning.

“Corresponding brain centers — the mushroom body in arthropods, marine worms, flatworms and, possibly, the hippocampus of vertebrates — appear to have a very ancient origin in the evolution of animal life,” Strausfeld said.

So why do the most commonly studied crustaceans have mushroom bodies that can appear so drastically different from their insect counterparts? Strausfeld and his co-authors have a theory: Crustacean species that inhabit environments that demand knowledge about elaborate, three-dimensional areas are precisely the ones whose mushroom bodies most closely resemble those in insects, a group that has also mastered the three-dimensional world by evolving to fly.

“We don’t think that’s a coincidence,” Strausfeld says. “We propose that the complexity of inhabiting a three-dimensional world may demand special neural networks that allow a sophisticated level of cognition for negotiating that space in three dimensions.”

Lobsters and crabs, on the other hand, spend their lives confined mostly to the seafloor, which may explain why they’ve historically been said to lack mushroom bodies.

“At the risk of offending colleagues who are partial to crabs and lobsters: I view many of these as flat-world inhabitants,” Strausfeld says. “Future studies will be able to tell us which are smarter: the reef-dwelling mantis shrimp, a top predator, or the reclusive lobster.”

Strausfeld co-authored the paper with two of his former students — Gabriella Wolff, now a post-doctoral fellow at the University of Washington, and Marcel Sayre, now a doctoral student at Lund University in Sweden. They hope that the study of mushroom bodies will further help in resolving how brains may have evolved and what environmental conditions shaped that process.

This research moves us closer to answering the ultimate question,” Strausfeld says. “We want to know: What was the earliest brain like?”

Giant seed shrimp on video


This November 2019 video says about itself:

Weird and Wonderful: The giant seed shrimp looks like a swimming orange ping-pong ball

Ostracods are a class of crustaceans, sometimes known as seed shrimp. The deep-sea giant ostracod, Gigantocypris, is 30 times bigger than regular ostracods. Its body resembles a shrimp but is completely encased within a clamshell-like carapace. It lives in the midwater and is nearly neutrally buoyant. It swims by rowing its long, feathery antennae, which are also used for feeding. Its eyes are enormous and shaped like parabolic mirrors to help spot bioluminescent prey in the dark ocean depths. It broods its embryos inside the carapace until they are quite large and well-developed.

Video editor: Ted Blanco
Writer: Kyra Schlining
Production team: Nancy Barr, Nancy Jacobsen Stout, Heidi Cullen

Fossil ‘spider’ was dinosaur age crayfish


This 2015 video says about itself:

This is part/counterpart example of a fossil crayfish, Cricoidoscelosus aethus (Subphylum Crustacea, Class Malacostraca, Order Decapoda, Superfamily Astacidea, Family Cricoscelosidae) dating to the Lower Cretaceous ~128 million years ago from the Yixian Formation, Lingyuan, Liaoning Province in China.

From the University of Kansas in the USA:

A ‘Jackalope‘ of an ancient spider fossil deemed a hoax, unmasked as a crayfish

December 19, 2019

Summary: A team used fluorescence microscopy to analyze the supposed spider and differentiate what parts of the specimen were fossilized organism, and which parts were potentially doctored.

Earlier this year, a remarkable new fossil specimen was unearthed in the Lower Cretaceous Yixian Formation of China by area fossil hunters — possibly a huge ancient spider species, as yet unknown to science.

The locals sold the fossil to scientists at the Dalian Natural History Museum in Liaoning, China, who published a description of the fossil species in Acta Geologica Sinica, the peer-reviewed journal of the Geological Society of China. The Chinese team gave the spider the scientific name Mongolarachne chaoyangensis.

But other scientists in Beijing, upon seeing the paper, had suspicions. The spider fossil was huge and strange looking. Concerned, they contacted a U.S. colleague who specializes in ancient spider fossils: Paul Selden, distinguished professor of invertebrate paleontology in the Department of Geology at the University of Kansas.

“I was obviously very skeptical,” Selden said. “The paper had very few details, so my colleagues in Beijing borrowed the specimen from the people in the Southern University, and I got to look at it. Immediately, I realized there was something wrong with it — it clearly wasn’t a spider. It was missing various parts, had too many segments in its six legs, and huge eyes. I puzzled and puzzled over it until my colleague in Beijing, Chungkun Shih, said, ‘Well, you know, there’s quite a lot of crayfish in this particular locality. Maybe it’s one of those.’ So, I realized what happened was I got a very badly preserved crayfish onto which someone had painted on some legs.”

Selden and his colleagues at KU and in China (including the lead author of the paper originally describing the fossil) recently published an account of their detective work in the peer-reviewed journal Palaeoentomology.

“These things are dug up by local farmers mostly, and they see what money they can get for them,” Selden said. “They obviously picked up this thing and thought, ‘Well, you know, it looks a bit like a spider.’ And so, they thought they’d paint on some legs — but it’s done rather skillfully. So, at first glance, or from a distance, it looks pretty good. It’s not till you get down to the microscope and look in detail that you realize they’re clearly things wrong with it. And, of course, the people who described it are perfectly good paleontologists — they’re just not experts on spiders. So, they were taken in.”

In possession of the original fossil specimen at KU, Selden teamed up with his graduate student Matt Downen and with Alison Olcott, associate professor of geology. The team used fluorescence microscopy to analyze the supposed spider and differentiate what parts of the specimen were fossilized organism, and which parts were potentially doctored.

“Fluorescence microscopy is a nice way of distinguishing what’s painted on from what’s real,” Selden said. “So, we put it under the fluorescence microscope and, of course, being a huge specimen it’s far too big for the microscope. We had to do it in bits. But we were able to show the bits that were painted and distinguish those from the rock and from the actual, real fossil.”

The team’s application of fluorescence microscopy on the fossil specimen showed four distinct responses: regions that appear bright white, bright blue, bright yellow, and ones that are dull red. According to the paper, the bright white areas are probably a mended crack. The bright blue is likely from mineral composition of the host rock. The yellow fluorescence could indicate an aliphatic carbon from oil-based paint used to alter the crayfish fossil. Finally, the red fluorescence probably indicates the remnants of the original crayfish exoskeleton.

“We produced this little paper showing how people could be very good at faking what was clearly a rather poor fossil — it wasn’t going to bring in a lot of money — and turning it into something which somebody bought for quite a lot of money, I imagine, but it clearly was a fake,” the KU researcher said.

Selden said in the world of fossils fakery is commonplace, as impoverished fossil hunters are apt to doctor fossils for monetary gain.

What’s less common, he said, was a fake fossil spider, or a forgery making its way into an academic journal. However, he acknowledged the difficulty of verifying a fossil and admitted he’d been fooled in the past.

“I mean, I’ve seen lots of forgeries, and in fact I’ve even been taken in by fossils in a very dark room in Brazil,” he said. “It looked interesting until you get to in the daylight the next day realize it’s been it’s been enhanced, let’s say, for sale. I have not seen it with Chinese invertebrates before. It’s very common with, you know, really expensive dinosaurs and that sort of stuff. Maybe they get two fossils and join them together, this kind of thing. Normally, there’s not enough to gain from that kind of trouble with an invertebrate.

“But somebody obviously thought it wasn’t such a big deal to stick a few legs onto this, because a giant spider looks very nice. I’m not sure the people who sell them necessarily think they’re trying to dupe scientists. You tend to come across these things framed — they look very pretty. They’re not necessarily going to be bought by scientists, but by tourists.”

Selden’s coauthors on the paper were Olcott and Downen of KU, along with Shih of Capital Normal University in Beijing, and Dong Ren of Capital Normal University and the Smithsonian Institution, and Ciaodong Cheng of Dalian Natural History Museum.

Selden didn’t know the eventual fate of the enhanced spider fossil, which he likened to the famed “jackalope.”

He said he thought it would go back to China where it could be put on display as a cautionary tale. One thing is for certain: it will be stripped of the scientific name Mongolarachne chaoyangensis and rechristened as a crayfish. Because of the fossil’s alterations and state of preservation, Selden said it was hard to pin down its exact species. The team tentatively placed the fossil in Cricoidoscelosus aethus, “because this is marginally the commoner of the two crayfish recorded from the Yixian Formation.”

How mantis shrimp think, new research


This 2013 video says about itself:

World’s Fastest Punch | Slow Motion Mantis Shrimp | Earth Unplugged

The peacock mantis shrimp has the world’s fastest feeding strike of any animal. Can Sam and Si capture this lightning-fast punch?

From the University of Arizona in the USA:

How mantis shrimp make sense of the world

November 25, 2019

A study involving scientists at the University of Arizona and the University of Queensland provides new insight into how the small brains of mantis shrimp — fierce predators with keen vision that are among the fastest strikers in the animal kingdom — are able to make sense of a breathtaking amount of visual input.

The researchers examined the neuronal organization of mantis shrimp, which are among the top predatory animals of coral reefs and other shallow warm water environments.

The research team discovered a region of the mantis shrimp brain they called the reniform (“kidney-shaped”) body. The discovery sheds new light on how the crustaceans may process and integrate visual information with other sensory input.

Mantis shrimp sport the most complex visual system of any living animal. They are unique in that they have a pair of eyes that move independently of each other, each with stereoscopic vision and possessing a band of photoreceptors that can distinguish up to 12 different wavelengths as well as linear and circular polarized light. Humans, by comparison, can only perceive three wavelengths — red, green and blue.

Therefore, mantis shrimp have much more spectral information entering their brains than humans do. Mantis shrimp seem to be able to process all of the different channels of information with the participation of the reniform body, a region of the animal’s brain found in the eyestalks that support its two protruding eyes.

Researchers Hanne Thoen and Justin Marshall at Queensland Brain Institute at the University of Queensland in Brisbane, Australia, teamed up with Nicholas Strausfeld at the University of Arizona, as well as scientists from Lund University in Sweden and the University of Washington in the U.S. to gain a better understanding of how the reniform bodies connect to other parts of the mantis shrimp brain and gather clues to their functional roles.

Using a variety of imaging techniques, the team traced connections made by neurons in the reniform body and discovered that it contains a number of distinct, interacting subsections. One particular subunit is connected to a deep visual center called the lobula, which is structurally comparable to a simplified visual cortex.

“This arrangement may allow mantis shrimp to store quite high-level visual information,” said Strausfeld, senior author of the paper that was published in the Journal of Comparative Neurology.

“Mantis shrimp most likely use these subsections of the reniform body to process different types of color information coming in and organize it in a way that makes sense to the rest of the brain,” said lead author Thoen. “This would enable them to interpret a large amount of visual information very quickly.”

One of the study’s crucial findings was that neural connections link the reniform bodies to centers called mushroom bodies, iconic structures of arthropod brains that are required for olfactory learning and memory.

“The fact that we were now able to demonstrate that the reniform body is also connected to the mushroom body and provides information to it, suggests that olfactory processing may take place in the context of already established visual memories,” said Strausfeld, Regents Professor of neuroscience and director of the Center for Insect Science at the University of Arizona.

The discovery of the reniform body, however, is not limited to mantis shrimp. It has been identified in other species as well, including shore crabs, shrimp and crayfish.

In 2016, an Argentinian group discovered that, in crabs, what are now known as reniform bodies act as secondary centers for learning and memory. According to Strausfeld, this suggests that the formation and storage of memories occurs in at least two different and discrete sites in the brain of the mantis shrimp and likely other members of malacostracans, the largest class of crustaceans. In addition to mantis shrimp, malacostracans include crabs, lobsters, crayfish, shrimp, krill and other less familiar species that together account for about 40,000 living species and a great diversity of body forms.

Reniform bodies have not been identified in insects and may be uniquely crustacean attributes, the researchers say. Alternatively, they might be homologous to a structure found in insect brains called the lateral horn, which sits between the optic lobes and the mushroom bodies. Strausfeld pointed out that fruit fly research done by other groups showed that the lateral horn is crucial in assigning values to learned olfactory information.

“The hunt is now on to determine if insects have a homologous center,” he said. “If we are looking for homologs in other arthropods, the reniform body would be the obvious candidate.”

The study was funded in part by the Asian Office of Aerospace Research and Development (12?4063), the Australian Research Council (FL140100197) and the National Science Foundation (11754798).

Disco clams and mantis shrimp, new research


This August 2016 video says about itself:

Ctenoides ales, also known as the “electric disco clam“, is lighting up tropical waters with its resemblance to a flashing neon light.

From the University of Colorado at Boulder in the USA:

Mantis shrimp vs. disco clams: Colorful sea creatures do more than dazzle

November 18, 2019

Summary: A researcher encountered a colorful creature called a disco clam in an Indonesian reef. Now, recent research suggests that she may be narrowing in on answering why this bivalve looks so wild.

When Lindsey Dougherty was an undergraduate student at CU Boulder in 2011, she got the chance to visit North Sulawesi, Indonesia, on a research trip. There, in the clear tropical waters off the coast, she encountered an animal that would change the course of her career.

It was the disco clam (Ctenoides ales). And it caught Dougherty’s eye for good reason: Even in a coral reef, these tropical bivalves are explosions of color. They have bright-red appendages that dangle out of their shells and thin strips of tissue that pulse with sparkly light like a disco ball — hence their name.

In that moment, she found her research calling.

“How do they flash?'” Dougherty remembered thinking as she dove through the reef with scuba gear.

As a graduate student at the University of California, Berkeley, the young scientist solved that first puzzle: the clams, she discovered, carry tiny, silica spheres in their tissue.

Now back in Colorado as an instructor in the Department of Ecology and Evolutionary Biology (EBIO), Dougherty is pursuing an even trickier mystery: Why are these bivalves so colorful in the first place?

The answer could reveal new clues to how the interaction between species drives the evolution of ocean animals over millions of years.

It’s a pursuit that has expanded to include several high school students and introduced Dougherty to an animal that may be even more groovy-looking than the disco clam — a fierce predator on the same coral reefs called the peacock mantis shrimp (Odontodactylus scyllarus).

This 2016 video from a German aquarium is about a peacock mantis shrimp.

And in a recently published paper in the journal Royal Society Open Science, she and her colleagues report that they may be finally getting close to solving that puzzle.

“It’s a long time to spend on one organism,” Dougherty said. “But I think it also shows how many questions there are about one seemingly simple clam.”

Clams vs. mantis shrimp

To grasp Dougherty’s obsession with this shelled organism, it helps to understand the weirdness of the disco clam.

Jingchun Li is a curator of invertebrates at the CU Museum of Natural History and advised Dougherty during her postdoctoral studies at CU Boulder. Li has spent her career exploring the diversity of the world’s bivalves — a class of aquatic mollusks that include animals like clams, scallops and mussels.

“Normally, if you think about clams like the ones in clam chowder — they’re little white things,” said Li, also an assistant EBIO professor. “But these clams are so colorful. One hypothesis we had is this might be some sort of warning signal to predators saying, ‘Don’t eat me.'”

In other words, disco clams might taste really bad, and they advertise that to the world using their bright colors. Kind of like a coral reef version of poison dart frogs in the Amazon.

To test that idea, Li and Dougherty recruited several peacock mantis shrimp — which, despite their names, aren’t actually shrimp — and kept them in tanks on the CU Boulder campus.

Like disco clams, these animals are pretty wild to look at. They come in a rainbow of colors, from blues and greens to neon orange and yellow. But don’t let their appearance fool you. Known for their powerful punches, mantis shrimp can extend their front claws at speeds of nearly 75 miles per hour — fast enough to generate an underwater shock wave that can shatter aquarium glass on impact.

The researchers, in other words, set up an ecological contest between the colorful mantis shrimp and flashing clams.

They offered their mantis shrimp a choice between two types of disco clam tissue. The mantis shrimp could either eat bright-red meat from the clams’ exterior or normal, white meat from their inner muscles.

The mantis shrimp didn’t even hesitate. They went for the white meat.

“It turns out they really hate the red tissue,” Li said.

That, along with chemical analyses of the two types of meat, certainly seemed to suggest that the team’s poison dart frog hypothesis had been spot on.

But another wrinkle emerged: When the group offered the mantis shrimp white meat that was dyed to look red, the invertebrates still chowed down.

As Dougherty put it, “Whether or not the red color is a warning needs more research.”

Vinegar vs. Sriracha

It’s work that’s happening now in Li’s lab. She’s hoping to discover whether the same mantis shrimp can learn to fear the color red — a key step in determining whether that shade may act as a warning signal.

Aiding Li in that effort are two seniors from Monarch High School in Louisville, Colorado, who are helping out in her lab through the Science Research Seminar program in the Boulder Valley School District. They’re tackling a pretty basic question: What kinds of food taste gross to a mantis shrimp?

The students, Grateful Beckers and Elysse DeBarros, have spent their semester trying out different flavor combinations, which they add to chunks of supermarket shrimp meat. Once they find a suitably yucky taste, they’ll mix it with meat dyed red to see if mantis shrimp will become wary of that hue over time.

Early results suggest that mantis shrimp can’t stand the taste of vinegar but, like many people, don’t seem to mind Sriracha sauce.

“They’re so unique,” Beckers said. “They’re a large, interesting shrimp with a lot of interesting adaptations.”

Dougherty herself may still have a way to go before she resolves the mystery that first caught her attention on the Indonesian reef all those years ago. But it’s been a fascinating road of discovery for this Colorado native who first learned to scuba dive in the Pueblo Reservoir.

“I love the mountains, and I love diving. I don’t think they should ever be mutually exclusive,” Dougherty said. “Everyone is connected to the ocean whether they realize it or not.”

Other coauthors on the new research included Alexandria Niebergall of UC Berkeley, Corey Broeckling of Colorado State University and Kevin Schauer of the University of Wisconsin-Madison.