by Amanda Kahn, Invertebrate Zoology and Molecular Ecology Lab
In our Ask a Grad Student page, Leeanna asked a bunch of really good questions, and all revolve around bivalves. Now, maybe you think you don’t know bivalves well enough to have them over for dinner, but I expect that many of you actually have had them FOR dinner! Bivalves include clams, mussels, oysters, scallops, and other generally clam-shaped animals with two shells. Class Bivalvia is within Phylum Mollusca, and its closest neighbors on the evolutionary tree are Classes Monoplacophora (extinct, snail-like animals), Polyplacophora (chitons), Gastropoda (snails and slugs), Scaphopoda (tusk shells), and Cephalopoda (octopuses and squids). Too much information? Too much information. Sorry. On to the questions!
Q: How do bivalves pump out water?
A: On each side of the foot inside of the bivalve (let’s say, for example, a clam), there are two big hollows, called mantle cavities. On one end of the bivalve’s shell, there is an inhalant and exhalant siphon, which the clam uses to pump water in and out of the mantle cavities.
Q: How do bivalves eat their food?