Posted by: lauraearly | March 22, 2011

Wait, lightning whelks don’t have hands, do they?

No, shells don’t have hands, but they can be either right-handed or left-handed. Gastropods, those creatures we call snails, either spiral to the left or the right.

Most gastropods are right-handed (dextral), but the lightning whelk is left-handed (sinistral). If you find a left-handed shell, it is most likely a lightning whelk because they are one of the only left-handed shells found in Florida. Another great identifying feature are the lightning-like streaks that run down the length of the shell.

Small lightning whelk.

Lightning whelks hatch from egg cases as miniature versions (called protoconchs) of the shells that we find washed up on the beach. As the whelk grows, the shell grows too. Lightning whelks can grow pretty large– some measure longer than a foot!

Whelk egg case.

A live lightning whelk's body

Unlike other gastropods that use their tongue-like structure called a radula to drill into the shells of its prey, the lightning whelk uses its muscular foot and the edge of its shell to pry open oysters and clams.

So, to figure out if your shell is right-handed or left-handed, go ahead and shake hands with it. Hold it with the broad end pointed up and the skinny end pointed toward the ground. If you were going to stick your fingers in the opening with your thumb pointing up and follow the spiral around, which hand would you use? If your left hand goes in, you have found a left-handed shell!

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