Weird Animals: Crabs With Ultraviolet Vision Among Seafloor Creatures Seen In Caribbean

From glowing coral to shrimp that vomit light-making chemicals, seafloor creatures can create quite the flashy visual show, according to researchers who traveled into the inky depths of the Caribbean Sea to investigate the oddballs.

Even so, the researchers reported today (Sept. 6) seafloor creatures are less flashy than their open-ocean cousins. In the open sea, an estimated 90 percent of organisms have the capacity to glow, compared with a paltry 10-20 percent of seafloor dwellers.

"We were surprised by how little bioluminescence is down there," Tamara Frank, a marine ecologist at Nova Southeastern University and study coauthor, told LiveScience.

The researchers did, however, find an abundance of bioluminescence from plankton, creatures that cannot swim against a current and instead glow bluish after bumping into other organisms and structures.

The glowers at the ocean bottom included the world's first identified glow-in-the-dark anemone along with a shrimp species that vomits light as a defense mechanism, glowing coral, starfish and sea cucumbers. [See Photos of the Glowing Deep-Sea Creatures]

In the Caribbean, glowing organisms don't just make for a visual spectacle, but also have finely honed visual systems that may allow bottom dwellers to distinguish what's a meal and what's poison, a sort of color-coding vision.

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