Posted by Erin, Paul, on March 23, 2004

Q: Hi! We have three questions for you.

1. Do saltwater clams disperse their eggs differently than fresh water clams?

2. How do clams catch their prey/food?

3. Why do clams put their larvae on fish?

Thanks, from a small class (4 kids) in a little school, in a tiny town in Southeast Alaska!

A: > 1. Do saltwater clams disperse their eggs differently than fresh water clams? Actually, it's the larvae that are dispersed, not the eggs. The eggs remain in the adult until they've hatched. The marine (saltwater) clams have free-swimming larvae that can swim in the water column using tiny hairs (cilia). Once they are old enough, they settle to the bottom and become what we think of as typical clams.

>

> 2. How do clams catch their prey/food? Look again at the illustration just below the "A Little Bit More" and you'll notice the clam I've drawn has two siphons - one an intake and one an outgoing siphon. Water flows into the incoming siphon and the clam removes tiny bits of plant and animal life to digest and then the outgoing siphon ejects what's left.

> 3. Why do clams put their larvae on fish? Why questions are difficult ,if not impossible, to answer in science. All we know is that this procedure has evolved over a great deal of time and works for these animals. Different animals come up with different "strategies" or ways of doing things - those that work are kept, those that don't work fade away.

John Wiessinger ( March 24, 2004)