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November 11, 2002

Shifty-Eyed Crabs Are an Extreme Discovery

From a crab-loving city comes research on a shifty-eyed species of crab that only a scientist could love.

The Nov. 7 issue of Nature features the work of UMBC marine biologist and vision scientist Tom Cronin, who was part of a team of researchers studying the amazing eyes of Bythograea thermydron, a rarely seen species of crab that thrives in the extreme heat and darkness of thermal vents two-and-a-half kilometers beneath the Pacific Ocean. The crab's unusual and little-understood visual system makes it quite a scientific catch, since its vision changes three times during its life cycle as it adapts to environmental changes.

Cronin is a marine vision specialist who has dived around the globe while conducting research as a faculty member at UMBC. For two years, Cronin's colleagues at the University of Delaware searched the dark depths of the Pacific near the Galapagos Islands before making a lucky grab with the claws of the deep-sea submersible ALVIN that yielded an adult Bythograea thermydron with a cluster of eggs attached to its shell.

"It's a radical change in vision and an exciting discovery because these crabs are so hard to come by and the larvae are even tougher to find," says Cronin.

The research team successfully hatched the eggs in a darkened lab to track the visual metamorphosis and was amazed at what they saw. The larval stage, which develops in the blue light of the ocean's middle depths, has a compound eye like an insect. As they mature, they head for deeper, darker waters, and their eyes adapt to see fainter light like that of bioluminescence. By the adult stage, the crabs reach the thermal vents where their retinas seem to be capable of visualizing heat from water percolating from the vents.

This is the third Nature appearance for Cronin, who was also recently awarded a Graduate Education Award for Excellence in Teaching and Dedicated Service from the University of Maryland Graduate Student Organization. Earlier this fall, Cronin was elected as a Fellow of the American Academy for the Advancement of Science for his work on the ecology of animal vision.

Posted by dwinds1 at November 11, 2002 12:00 AM