You might be surprised at how much wood there is at the bottom of the ocean. (123RF)

You might be surprised at how much wood there is at the bottom of the ocean. (123RF)

A wood-boring clam is shown burrowed into a piece of wood. (Jenna Judge)

A wood-boring clam is shown burrowed into a piece of wood. (Jenna Judge)

Wood-boring clam (Bernardino and Sumida)

Wood-boring clam (Bernardino and Sumida)

Wood-Eaters!

Posted: July 1, 2019

Want a big bite of wood? These clams do! And while they’re munching on trees, their family tree is growing!

You know a clam when you see one. It lives in the ocean. It has two shells and a squishy inside. But these wood-boring clams are like no other creatures. They burrow into wood that has washed into the sea. They rock their shells against the wood. Wood bits scrape off. The clams digest them! Only two other critters eat wood: termites (insects that will chew up your house) and shipworms (mollusks that will gnaw on sunken ships). Now researchers learn: The wood-boring clam clan is a lot bigger than they thought. Researchers have discovered around 60 different species of them! That’s a good thing. This family of clams has a big job. They’re the cleaning crew that takes care of all the wood that winds up in the ocean.

The researchers had to be very careful when deciding whether each kind of clam belonged to a different species. The kinds of clams didn’t always look different on the surface, even if they were different. And some of the adult clams had shells smaller than peas! If one clam seemed different from another, the researchers double-checked their DNA. They found that the clams could be divided into six groups called genera. (“Genera” is the plural of “genus.”) Three of these groups were brand-new discoveries.

How do such teeny-tiny creatures do such a big job? There is strength in numbers! The clams live in huge groups where wood needs chomping.

“We have no idea how much wood is at the bottom of the ocean. But there’s probably a lot more than we think,” says the clam study’s lead author, Janet Voight. Her study was published in the Journal of Molluscan Studies. She guesses that a big storm washes millions of tons of wood into the sea. She asks, “What if these clams weren’t there to help eat it?”