SCIENCE LAB SPECIAL : ABSORBING HABITATS

 

SPONGEBOB lives in a pineapple. These sharks live in sponges. John Pogonski, an ichthyologist in Australia, wasn't about to be fooled by any moray eels.

He knew the serpentine fish like to hide among the nooks and crannies of large sponges. But as he surveyed sponges collected from a remote seabed off the coast of Western Australia, he stumbled on a complete surprise - a small shark tail poking out of a sponge's cavernous body.

The errant tail belonged to Atelomycterus fasciatus, better known as a banded sand catshark. And it wasn't alone. Mr. Pogooski, who works at the Commonwealth Scientific and Industrial Research Organization, or CSIRO, and his colleagues found as many as 30 of the petite predators packed into just one sponge.

The discovery, reported in the Journal of Fish Biology, is the first record of any shark using the inside of a sponge as a habitat.

The word ''shark'' may conjure images of gargantuan great whites of hefty hammerheads. But the cartilaginous carnivores come in many sizes. The banded sand catshark, maxing out around a foot and a half in length, about 45 centimeters, is on the smaller end of the spectrum.

'' This small size makes them quite vulnerable to predation by larger sharks and fish,'' said Helen O'Neill, a fish biologist at CSIRO's Australian National Fish Collection in Tasmania and an author of the paper.

At night the catsharks prowl the seafloor for prey, but Ms. O'Neill suspects that during the day ''they are hiding safely within the sponges'' to avoid becoming food themselves.  [Darren Incorvaia]