Wood-Eating Catfish ... Eating WoodA new species of armored, wood-eating catfish (pictured underwater) found in the Amazon rain forest feeds on a fallen tree in the Santa Ana River in Peru in 2006.

Other so-called suckermouth armored catfish species use their unique teeth to scrape organic material from the surfaces of submerged wood. But the new, as yet unnamed, species is among the dozen or so catfish species known to actually ingest wood.

Still, wood-eating catfish are largely unable to digest wood. Only associated organic material—such as algae, microscopic plants, animals, and other debris—gets absorbed into their bodies. The wood itself passes through the fish and is expelled as waste.

"The fish pass wood through their guts in less than four hours, which is incredibly fast for an animal that supposedly digests wood," said Donovan German, a biologist at the University of California, Irvine, who is researching the digestion of wood-eating catfish.

"People think they must have an amazing consortium of microbes in their guts to help the fish digest wood, but that isn't really what I've found," he added. "The amazing microbes are in the river, on the wood itself."

(Related: "World's Largest Catfish Species Threatened by Dam.")

—Ker Than

Photograph by Michael Goulding/Copeia