Outside of their boreholes, wood-boring clams are quite phallic in appearance. Photo by Angelo Bernardino and Paulo Sumida
April 2 (UPI) -- Wood-eating clams are more diverse than previously thought, and perhaps a bit more adult-rated -- the kind of clams one might find a bachelorette party.
"It turns out, once removed from their boreholes, the clams are pretty PG-13-looking," researchers admitted in a news release.
In a new survey of wood-munching clams, published this week in, the Journal of Molluscan Studies, scientists announced the discovery of a new species and three new genera.
For the study, clam experts sequenced the genomes of 59 specimens collected from water-logged wood pieces found on the seafloors of the northeastern Pacific, southwestern Pacific and the Atlantic oceans.
Along with termites and shipworms, wood-boring clams are one of only a few types of animals known to consume wood. The mollusks bore holes into the soft wood and live out their lives munching on wood shavings, which they break down with the help of special bacteria living in their gills.
As evidenced by the latest research, wood-boring clams are remarkably diverse.
"There's not just one tree-cleaner-upper in the ocean," Janet Voight, lead author of the new study and associate curator of invertebrate zoology at the Field Museum in Chicago, said in a news release. "Imagine living at the bottom of the ocean as a tiny swimming clam; you either have to find a sunken piece of wood or die. You wouldn't think there'd be that many kinds of clams doing this. But we've now found that there are six different groups, called genera, and around sixty different species."
Scientists confirmed the addition of three new genera and one new species after comparing the genomes and physiology of the dozens of clam specimens.
Researchers first organized the specimens by appearance. The DNA helped scientists ensure that they weren't seeing differences that weren't actually there.
"You think, am I seeing everything that's there, are there cryptic species, am I over-splitting them and going crazy?" said Voight. "It's really scary checking yourself against the DNA, but the results matching what I found gave me a lot of confidence."
Studying biology and ecology at the bottom of the ocean is difficult. Scientists almost always assume they're underestimating the quantities and diversity of species and materials found there. Voight said there is almost certainly more rotting wood than current estimates, and probably a number of undiscovered wood-boring clam species, too.
And it's a good thing there are.
"After big storms, we estimate that millions of tons of wood are washed out to sea. What if these clams weren't there to help eat it? Think how long it would take the wood to rot," Voight said. "The clams contribute to the cycling of carbon, 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. It could even affect sea level rise. It blows me away."