Profile

Whether diving into the coral reefs off of Australia to retrieve specimens or analyzing data in the lab, Alex Cheroske has his work cut out for him. Properly known as stomatopods but commonly known as mantis shrimp (although not a true shrimp), Cheroske has been researching these marine crustaceans since he began his Ph.D. studies in marine-estuarine-environmental sciences at UMBC in 1999.

Mantis shrimp are small, incredibly aggressive creatures that live in holes in the coral reef. They range in size from 2 centimeters to about 70 centimeters. When mantis shrimp strike they are capable of shattering glass. “We have one animal that’s broken heaters twice,” says Cheroske, of his lab specimens. With appendages that, among larger species, can strike with the force of a 22-caliber bullet, the mantis shrimp is formidably strong.

Most of Cheroske’s research, however, is centered on the abilities of the mantis shrimp to distinguish color. In addition to disproportionate strength, mantis shrimp have highly advanced color discrimination. “It could be considered to have the best color system of any animal,” says Cheroske. While human perception is based on three cones, which use three basic colors (red, green and blue), mantis shrimp have over 10 different pigment types as well as four that extend into ultraviolet. Moreover, it seems that mantis shrimp, like octopuses, are capable of modifying behaviors based on experience.

One published experiment by Marshall et al. in 1996 involved training mantis shrimp to look for food based exclusively on color. As part of this process, a small cube is constructed. On one side of the cube, there is a piece of colored glass. During the early part of the experiment, each mantis shrimp grasps the cube (colored red), where food is concealed. After a period of time the shrimp is taken out of the red cube. Then in a later trial, a similar red cube and two other differently colored cubes are added to the tank. Remarkably, the mantis shrimp still chooses the red cube, even though there is no food residue to smell. It learns through experience to recognize the red cube as the bearer of food.

In addition to their complex color vision, mantis shrimp also exhibit fascinating behavior. “They go through a fighting bout, where they’ll show part of their bodies,” says Cheroske. “They’ll use different colored body parts to send a message.” One example is called the “meral spread,” in which the animals take their claws, put them up, and spread them apart to reveal colored “eye spots” on their appendages. By using color signals and motions such as these, it seems that mantis shrimp can communicate with one another and avoid fighting to the death.

Currently, Cheroske has eight mantis shrimp in the lab. Along with Tom Cronin, director of UMBC’s marine-estuarine-environmental sciences graduate program, and Afsheen Siddiqi, a master’s student in the lab, Cheroske is using the protocol set up by Marshall et al. to look at polarization vision; specifically, whether or not the mantis shrimp can see “circularly polarized light,” an aspect of light that is imperceptible to human eyes. He is also in the continuing process of analyzing the data he collected over the summer on the ability of mantis shrimp to adapt their vision according to varying light environments at different depths.

Cheroske came to UMBC largely because of the opportunity it offered him to study the mantis shrimp. His advisor, Tom Cronin, had worked extensively with stompatopods beforehand. “For my masters, I did a lot of work with coral reef ecology, especially algae,” says Cheroske. “After I was done with that, I wanted to start with the organismal level, eventually scaling up from the animal itself to working with the ecology [associated with the animal]. When Tom and I contacted each other, the mantis shrimp seemed like a perfect fit.”

As Cheroske’s advisor, Cronin has opened many doors. “He’s a really well-known, respected vision biologist. He introduced me to people all around the world,” says Cheroske. “Also, he’s typically very well-funded. NSF knows that he does good work. In that way, there’s money to travel and collect animals and data from a variety of habitats.”

Cheroske admits that obtaining a Ph.D. is a long and sometimes arduous process. However, it’s worth it in the end, he asserts. “I could quit right now and I could get a real job behind a computer, or I could have the chance to go diving off the reef and collect animals.” For Cheroske, the sacrifices are worth the rewards.

For More Information
For more information about the maurine-estuarine-environmental sciences graduate program, contact:

Dr. Tom Cronin
cronin@umbc.edu
410-455-3449
http://www.umbc.edu/biosci/Faculty/cronin.html