The mysterious, fascinating, and lightning-quick mantis shrimp: An Interview with Maya deVries
Jeremy Hancemongabay.com
August 26, 2009
Maya deVries is a graduate student studying integrative biology at Berkeley. Mongabay.com's fourth in a new series of interviews with 'Young Scientists'.
|
|
But Maya's first look at the mantis shrimp on her advisor's website left an impression: "I was struck by the amazing capacity of mantis shrimp to capture fish and smash shells with only a few powerful blows, something a fish could only dream of doing. After a more careful read of the website, I realized that the kinds of questions that Sheila aimed to answer in mantis shrimp were very similar to the ones that I was studying… My visit to her lab marked my first exciting encounter with mantis shrimp. Hearing the animals smash their snail prey for the first time convinced me that these were the animals that I wanted to study."
 Maya deVries at the Galeta Marine Laboratoty in Panama. |
Maya de Vries and her advisor, Dr. Sheila Patek, have spent a lot of time looking at the mantis shrimps' super-fast, super-powerful appendages. There is simply nothing else like it.
"The claw acts like a bow and arrow in both spearing and smashing mantis shrimp. When you shoot an arrow, the first thing you do is slowly pull back on the bow so that the energy from your arm muscles loads the bow. When you release the bow, all of the energy built up in the bow is released over very short time scales, causing the arrow to fly forward at speeds much faster than would have been possible if you had just thrown the arrow with your arm alone. The mantis shrimp claw follows the same concept," deVries says, explaining how these small creatures' claws are able to reach record speeds.
 The strange-looking and beautiful mantis shrimp. This species is Odontodactylus scyllarus. Photo by Roy Caldwell. |
Maya deVries and Dr. Patek have recorded these strikes in high-speed videos (two videos are available at the end of the article) and one can see on film a flash of light as the mantis shrimp's strikes. This is the cativation bubble.
Maya says that while hardly any of the species of mantis shrimp are classified as endangered, they are threatened by the aquarium trade and overfishing. "The aquarium trade has probably devastated populations of mantis shrimp the most," says deVries. "Some of the most colorful and charismatic species are found in coral and coral rubble in the Indo-West Pacific. Aquarium traders collect these species with underwater cyanide bombs that stun all reef animals and decimate entire coral reef habitat. This practice not only seriously damages mantis shrimp populations, but it also demolishes entire coral reef ecosystems."
 Predatory appendage of mantis shrimp Lysiosquillina maculata. Photo by Roy Caldwell. |
Maya deVries discussed the evolution, feeding habits, and lightning-fast appendages of various species of mantis shrimp, as well as studying integrative biology at Berkeley and working at the world renowned Smithsonian Tropical Research Institute in Panama in a August, 2009 interview with Mongabay.com.
BACKGROUND
Mongabay: How did you become interested in wildlife? What is your background?
Maya deVries: I grew up about an hour away from the Pacific Ocean in Berkeley, CA and so the ocean was always a big part of my life. Growing up, I sent a lot of time exploring the tide pools and sandy beaches that are typical in northern California. However, my true fascination with the ocean is the warm tropical waters of coral reef ecosystems. My first introduction to the incredible diversity of life in coral reefs occurred no more than ten feet away from the shoreline. I took only a few steps into the aqua waters of Tahiti, French Polynesia before noticing humbug damselfish darting in and out of patches of coral, graceful stingrays gliding past my feet, and iridescent pipefish hovering near the surface of the water. My curiosity in coral reef animals began at this pivotal moment during college and I have been pursuing this interest ever since.
Mongabay: How does the integrative biology program at Berkeley differ from other biology graduate programs?
 Maya deVries collecting coral rubble at Galeta Marine Laboratory in Panama. |
Mongabay: You are currently at the Smithsonian Tropical Research Institute, what is it like working at this world-renowned facility?
Maya deVries: My field work on mantis shrimp feeding ecology occurs at the Smithsonian Tropical Research Institute (STRI), which is truly an exciting place to work. Scientists come from all over the world to conduct research at STRI. In fact, STRI itself has 38 staff scientists who study the many aspects of Panama’s tropical flora and fauna, both in the water and on land. My particular field site is on the Caribbean coast of Panama at the Galeta Marine Laboratory. Galeta Marine Laboratory is one of the six field stations that are run by STRI. This is a beautiful site with a dynamic inner-reef flat, white sand beaches, and mangroves. One of my favorite things about working at this site is actually its active marine education program. This program brings school groups from all over Panama to the marine station so that students can learn about the natural history of the area. This program has become a great outlet for teaching about marine biology, ecology, and conservation.
 Maya deVries explaining to local elementary children about her feeding experiment at Galeta. |
Maya deVries: Surprisingly, I did not even learn what a mantis shrimp was until I applied to work with my current Ph.D. advisor, Dr. Sheila Patek, at UC Berkeley, who is now moving to the University of Massachusetts Amherst. As an undergraduate, I conducted research in a lab that focused on understanding the evolution fish feeding. I came across the Patek Lab website when I was considering graduate school and looking for potential Ph.D. advisors. I was struck by the amazing capacity of mantis shrimp to capture fish and smash shells with only a few powerful blows, something a fish could only dream of doing. After a more careful read of the website, I realized that the kinds of questions that Sheila aimed to answer in mantis shrimp were very similar to the ones that I was studying in fish feeding systems. I wrote an email to Sheila describing why I thought our interests were well-matched and we set a time to meet in person. My visit to her lab marked my first exciting encounter with mantis shrimp. Hearing the animals smash their snail prey for the first time convinced me that these were the animals that I wanted to study.
Mongabay: Why do you think so little is known about mantis shrimp?
 Lysiosquillina maculata peaking its head out of its sandy burrow at Lizard Island, Australia. Photo by Erica Staaterman. |
Mongabay: What advice would you have for an undergraduate who is interested in applying to graduate school in biology?
Maya deVries: If you are interested in graduate school, I think the most important thing you can do is to get involved in research. There are usually many opportunities for research at universities for college students and even high school students. Don’t feel shy about surfing the web for labs that suit your interests and then emailing the professor who runs the lab to see if you can volunteer in the lab. Most professors are excited to learn that people are interested in their research, so it’s definitely worth a try. Also, research is not right for everyone and so you really want to know if you would be happy conducting research before committing to it in graduate school. One program that I would recommend is the National Science Foundation’s Research Experience for Undergraduates Program ().This program lists great opportunities for undergraduates looking to have their first meaningful research experience. However, I found my most memorable field experience by simply searching on-line. Before starting graduate school, I volunteered with a marine turtle monitoring program through the Charles Darwin Research Station on the Galapagos Islands.
MANTIS SHRIMP
 Lysiosquillina lisa refecting florecent light! Mantis shrimp vision is so accute, it can even see florecent light. Males use florecent light to signal to females. Photo by Roy Caldwell. |
Maya deVries: Mantis shrimp are fierce predators that eat everything from fish and snapping shrimp to snails, hermit crabs, and brittle starts. Because they eat so many different animals, they are very important players in coral reef food webs.
The most amazing thing about mantis shrimp to me is that they are 'number one' in so many ways. First, the mantis shrimp’s predatory strike has been documented to produce one of the fastest appendage movements ever reported in the animal kingdom. With predatory strikes that can generate speeds of over 20 m/s (50 miles per hour) and accelerations of up to 104 km/s2 (which are comparable to the accelerations of a .23 caliber bullet) the raptorial strike is certainly worthy of its title. Second, mantis shrimp are one of the fastest speeds swimmers in the sea. When a mantis shrimp is escaping from danger, it can reach speeds of around 30 body lengths per second. These speeds are comparable to those of squid and shrimp, which were the original record holders for fastest swimmers. Third, mantis shrimp have one of the most complex visual systems in the animal kingdom. They can see a very wide spectrum of light including polarized, UV, and infra-red light. Unlike humans who only have three visual pigments, mantis shrimp have 16, which is what allows them to see such a wide spectrum of light. Finally, mantis shrimp are considered to have one of the most complex communication systems in crustaceans, because of the many ways in which mantis shrimp signal to each other. For example, the males of some species have polarized signals on their tails and by their antennae which they use to signal to females. Since few animals can see polarized light, the polarized signal allows males to communicate with females without their predators noticing.
There are a few alternative hypotheses for how these traits evolved. One hypothesis for the evolution of the predatory appendage, in particular, is that it evolved from 'feeding feet,' which were used to pick food off of the substrate, to a spear-like appendage that was used to capture more evasive prey like fish and other crustaceans. Modern-day mantis shrimp with this spearing appendage are known as 'spearers'. However, another functional form of the appendage evolved around the same time. The smashing appendage has an enlarged hammer-like bulb at the base of the third segment of the appendage. The hammer is used to smash hard-shelled prey. Mantis shrimp with these appendages are known as 'smashers'. In both cases, the predatory appendage evolved for the function implied by the name, being fierce predators.
 Odontodactylus scyllarus has been documented to have one of the fastest appendage movements in the animal kingdom. Photo by Roy Caldwell. |
In terms of the evolution of the raptorial appendage, it is probably a combination of these two hypotheses. The evolution of the other 'number one' qualities in mantis shrimp, however, has yet to be discovered.
Mongabay: What are some of the major differences among the numerous species of mantis shrimp?
 Neogonodactlyus bredini with damage on its predatory appendage from another mantis shrimp's strikes! Photo by Roy Caldwell. |
Mongabay: Are any species of mantis shrimp threatened or endangered? If so what are the threats?
Maya deVries: Luckily, hardly any species of mantis shrimp are considered endangered or threatened. However, populations of certain species have suffered greatly due to over fishing in the Atlantic Ocean. Some species that live in sandy burrows are caught as bi-catch in trawls. There is also a big fishery for mantis shrimp in countries like French Polynesia, Indonesia, and Japan, so a few populations of the big spearing species have undergone serious declines. However, the aquarium trade has probably devastated populations of mantis shrimp the most. Some of the most colorful and charismatic species are found in coral and coral rubble in the Indo-West Pacific. Aquarium traders collect these species with underwater cyanide bombs that stun all reef animals and decimate entire coral reef habitat. This practice not only seriously damages mantis shrimp populations, but it also demolishes entire coral reef ecosystems.
 Maya deVries diving in the Great Barrier Reef for mantis shrimp. Photo by Thomas Claverie. |
Maya deVries: Yes! It is quite common to be smacked on the finger by a smashing mantis shrimp. It usually feels like a quick but hard pinch. However, getting speared by the spearing mantis shrimp often hurts a lot more. One of the world’s experts on mantis shrimp, Dr. Roy Caldwell, has been speared straight through his finger by the large species, Lysiosquillina maculate.
Mongabay: Mantis shrimp do appear in some aquariums and even on the dinner plate in certain cultures. What are your feelings on the practice of keeping mantis shrimps in aquariums—or eating them!?
Maya deVries: Mantis shrimp are beautiful creatures and so I understand why they are popular aquarium animals. Unfortunately, the methods that aquarium traders use to capture mantis shrimp and most other tropical marine animals are very detrimental to mantis shrimp populations and the surrounding ecosystem. The aquarium trade uses cyanide bombs to get animals out of their burrows and coral cavities. Most coral reefs essentially die after experiencing cyanide bomb attacks. Knowing this, I would advise against purchasing mantis shrimp and tropical fish from the aquarium trade.
Mantis shrimp are also considered a delicious treat in some countries. I think that fisheries for mantis shrimp are fine, as long as they are sustainable, meaning that they don’t diminish the mantis shrimp populations. However, few mantis shrimp fisheries are currently sustainable and most are over-fished. So, unless you know that your mantis shrimp was part of a sustainable fishery, I wouldn’t recommend eating it.
THE STRIKES OF THE SPEARERS AND THE SMASHERS
Mongabay: Mantis shrimp are most known for their lightning-fast claws, ending either in a spear or a hammer, can you tell us how these claws work?
 Propodus and dactyl of Neogonodactylus bredini's predatory appendage. Photo by Thomas Claverie. |
Mongabay: Can you tell us about 'cavitation bubbles'?
Maya deVries: Cavitation bubbles are vapor bubbles that form when water moves really fast. Basically, when water moves fast enough, areas of low pressure are created, which causes the water to vaporize and form cavitation bubbles. People who drive motor boats might be familiar with cavitation because propellers on motor boats suffer a lot of damage from cavitation bubbles. Cavitation bubbles can form when mantis shrimp strike, because the appendage moves so fast through water that it creates an area of low pressure around itself. When the pressure drops below a certain level, the water vaporizes and cavitation bubbles form. When these bubbles burst, energy is released in the form of light, heat, and sound. Bursting bubbles also generate forces that are equal to or greater than the forces produced by the strike itself.
Mongabay: Having studied the diet of mantis shrimp with smashers for claws, why do you think their diets are so varied when they seem to be perfectly made to specialize on hard-shelled prey?
 Smashing species, Gonodactylus falcatus, surrying about its coral rubble habitat at Lizard Island, Australia. Photo by Thomas Claverie |
I have a few hypotheses for why smashers have such varied diets. One hypothesis is that easy-to-catch soft-bodied prey types are less available in the environment than hard-shelled prey. Evolving faster speeds and higher accelerations allowed smashers to break snail shells and crabs shells as well as capture fish and other soft-bodied prey. Basically, smashers will never go hungry, because they can eat anything that crosses their path.
An alternative hypothesis is that fast speeds and high accelerations of the appendages actually evolved for fighting with other mantis shrimp competitors for space in coral cavities. If the impressive characteristics of the appendage evolved because of competition between mantis shrimp then we have a situation where, by change, it has also allowed for smashers to eat a much wider variety of prey than would have been possible otherwise.
Mongabay: Your work has also focused on spearing mantis shrimp—how do they differ from other mantis shrimp? What are their particular hunting techniques and prey?
 Lysiosquillina maculata, a spearer species whose appendages don't move as fast, but they have amazing reach. Here we see sexual dimorphism between the male (top) and female (bottom), photo by Roy Caldwell. |
Mongabay: Can you tell us about the kinematic analysis of the spearing mantis shrimp's strike?
 Hemisquilla californiensis, a california species whose appendage is thought to be a mix of both the spearer and smasher functional types. Photo by Roy Caldwell. |
Mongabay: How do you think the evolution of the spearing technique has affected the behavior of these mantis shrimp?
 Neogonodactylus bredini peaking its head out of a coral rubble cavity. Photo by Roy Caldwell. |
Mongabay: What have you discovered that was most surprising in your research?
 Maya gathering high speed vidoe data of Lysiosquillina maculata's predatory strike. |
In terms of my research on stomatopod diet, the most surprising thing I have discovered is that one species of smasher, Neogonodactylus bredini, feeds on different prey types in different habitats. One of the main focuses of my research is to figure out what exactly what mantis shrimp eat. This is easier said than done, because unlike most animals, mantis shrimp digest their prey really quickly so it is difficult to look inside of a mantis shrimp’s stomach to see what it eats. So, in N. bredini, I have been conducting a series of experiments to determine what a typical smasher species is able to able to kill and eat given its appendage anatomy. So far, it seems that N. bredini is able to eat everything from hermit crabs, snails, and crabs to small fish and snapping shrimp. However, my most interesting finding is that N. bredini will eat these prey types in different proportions, given the habitat that it lives in. For example, in sea grass, N. bredini probably eats mostly snails and hermit crabs, but in the coral rubble the majority of the diet is probably fish. My current hypothesis for why I see these differences is that the availability of the prey types is different in both habitats. In the coral rubble fish are more available, but in the sea grass, snails and hermit crabs are more available. Good thing N. bredini has a powerful appendage so that it can kill and eat almost anything!
Filmed at 5,000 frames per second, a peacock mantis shrimp strikes the shell of a snail. The flash that occurs a moment after impact is the cavitation.
Video of a spearing mantis shrimp in action.
Related articles
Plant communities changing across the globe, says scientist Sasha Wright
(03/29/2009) Having studied plant communities across three continent and within widely varied ecosystems—lowland tropics, deciduous forests, grasslands, and enclosed ecosystems on hill-tops—graduate student Sasha Wright has gained a unique understanding of shifts in plant communities worldwide as they respond to pressures from land use and global climate change. “Plant communities are certainly changing,” Wright told Mongabay.com in a March 2009 interview. “These changes are undoubtedly affected by an increased occurrence of extreme weather events, temperature fluctuations, atmospheric CO2 concentrations, human land use, and in some cases urbanization of populations.”
Seeking out the world’s rarest and most endangered birds
(02/02/2009) For an evolutionary biologist there is no conservation group whose work is more exciting than EDGE, a program developed by the Zoological Society of London (ZSL). Unique in the conservation world, EDGE chooses the species to focus on based on a combination of their threat of extinction and evolutionary distinctness. Katrina Fellerman, an evolutionary biologist herself and the EDGE birds’ coordinator, describes the organization as one that focuses on species, which “to put it bluntly, if lost, there would be nothing like them left in the world today”. Explaining further Fellerman says “We use evolutionary distinctiveness (ED) as a species-specific measure of the relative evolutionary value of species - it is a way of apportioning conservation value according to a species’ phylogenetic position. Species with few or no close relatives on the ‘tree of life’ have the highest ED scores.”
Embarking on a career in science? Learn from interviews with young scientists
(02/02/2009) Mongabay.com is excited to announce a new series of interviews with 'young scientists'. These interviews will focus on scientists who while only recently starting their career have already achieved notable success.
Saving leatherback turtles in South America’s smallest country, Suriname: An interview with Liz McHuron
(01/27/2009) After a year studying marine biology at Moss Landing Marine Labs, Liz McHuron headed off to the little-known nation of Suriname to monitor leatherback sea turtles. Her responsibilities included implementing a conservation strategy for a particular beach, moving leatherback nests in danger of flooding, and educating volunteer workers on the biology, behavior, and conservation efforts of the world's largest, and most unique, marine turtle. I visited McHuron during her time at the beach of Galibi in Suriname; she proved to be the sort of scientist who refused to be deterred: breathtaking humidity or downpours, fer-de-lances on the beach or jaguars, Liz was always on the move, always working to aid the critically-endangered leatherbacks while studying them with the thoroughness inherit in a born scientist.
