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UT Researcher Learns Cleaning is a Big Job for Little Shrimp

Published: June 15, 2009

For marine science-biology double major Lauren Van Maurik, big things come in small packages.
“Our guys are pretty little,” she said. “For shrimp, they’re on the small end.”
The junior’s research on Hawaiian river shrimp, a crustacean about the size of a cashew, has netted her two research awards, the Department of Biology’s $3,000 Summer Research Fellowship grant and a head start on graduate school.
Since July 2008, she and Dr. Jen Wortham, a UT exercise science and sport studies associate professor, have studied the grooming habits of the species Macrobrachium grandimanus. How and how often these shrimp clean themselves is a matter of life and death. Debris flowing through the river can collect on them “like barnacles” and lodge in their gills, Van Maurik said. Too much build-up could paralyze or even suffocate them.
To make matters worse, development in Hawaii is destroying their habitat, causing erosion and creating more run-off.
“The more gunk added to the water, the more the shrimp need to clean,” Wortham said.
They clean a lot, Van Maurik and Wortham’s research shows. Whereas other species, such as mantis shrimp, devote 3 to 4 percent of the day to grooming, the Hawaiian river variety spends about a quarter of their day cleaning themselves. Imagine taking a six-hour shower every day.
And these tiny creatures don’t just lather up the shower gel on their luffa. Grooming is hard work. The shrimp scrape, scratch and pick off dirt and debris with their front claws and back legs, even reaching inside their mouths to clean their gills.
Van Maurik and Wortham’s main research method is observation, including 24-hour, bleary-eyed vigils spent in the Marine Behavioral Research Laboratory in Walker Hall to see if the tiny creatures groom more during the day or at night.

Hawaiian river shrimp
Hawaiian river shrimp.

“They really start moving at night,” Van Maurik said.
They’re also trying to figure out the function of the mysterious “hair” patch (or “setal,” as it’s known to scientists) on the inside of the shrimp’s larger claw. They had suspected the fastidious crustacean would use it to brush dirt off its body.
“After over 30 hours of watching this shrimp, it wasn’t used once. It’s so weird,” Wortham said.
Why study Hawaiian river shrimp? Little is known about the species, which is always an open invitation for researchers. The opportunity arose when UT assistant professor of biology Dr. Mark McRae, who is a Hawaiian conservation ecologist and is collaborating on the project, got the shrimp from the Hawaii Division of Aquatic Resources. 
Van Maurik and Wortham will continue their research into next year. They hope to present their findings January 2010 at The Society of Integrative and Comparative Biology’s international conference in Seattle.    
The research awards Van Maurik won include the Florida Academy of Sciences’ outstanding undergraduate paper in the biological sciences and the American Association for the Advancement of Science’s best student presentation by a female undergraduate. Van Maurik is one of two undergraduates to receive a biology department research fellowship.
Wortham graduated from UT in 1995 with a marine science degree and earned a Ph.D. in evolutionary biology from the University of Louisiana – Lafayette. Her research focuses on crustacean behavior, especially mantis shrimp.