Image of the Day: Not What You Think

Newly discovered and rather phallic-looking clams dwell at the bottom of the ocean and are some of only a few animals known to eat wood.  

Apr 4, 2019
Carolyn Wilke
One of the newly described wood-boring clams
© ANGELO BERNARDINO AND PAULO SUMIDA, BIOTA-FAPESP GRANT 2011/50185-1

At the bottom of the sea, tiny clams munch on sunken wood, boring holes that they turn into homes. Now researchers have added a new species and several genera to the family tree of wood-boring clams, researchers report April 2 in Journal of Molluscan Studies.

A line drawing showing several members of the wood-boring clam family
(© Lisa Kanellos

The clams may appear appropriate for mature audiences only, but they’re fascinating for more than their bizarre looks. They eat wood and are some of the only known creatures, including termites and shipworms, to do so. To work their way into wood, the creatures scrape their shells against its surface, shaving it into sawdust that they digest with the help of microbes. As they burrow headfirst into the wood, they breathe with the help of a siphon, a protruding tube-like organ, with which they suck in ocean water to obtain oxygen. 

Despite their small size—some possess shells more minute than a pea—the clams may play a major role in ecosystems of the deep. “We have no idea how much wood is at the bottom of the ocean, but there’s probably a lot more than we think,” Janet Voight, one of the study’s authors and the Associate Curator of Invertebrate Zoology at the Field Museum, says in a statement. “What if these clams weren’t there to help eat it? Think how long it would take the wood to rot. The clams contribute to the cycling of carbon, [and] they play an integral part in making the wood into something that the other animals at the bottom of the ocean can get energy from.”

J.R. Voight et al., “Life in wood: preliminary phylogeny of deep-sea wood-boring bivalves (Xylophagaidae), with descriptions of three new genera and one new species,” Journal of Molluscan Studies, doi:10.1093/mollus/eyz003, 2019.