Lewis's Moon Snail
The Lewis's Moon Snail (Neverita lewisii) is one of our largest intertidal gastropods (stomach-foot). Up to 5 inches across, these mollusks plow through the sand looking for their favorite prey...clams! Their fleshy mantle extends out of the shell and surrounds the lower portion; it is so large that it doesn't appear that it could fit back inside! Unfortunately, I could not find a live specimen with the mantle extended to show you, but above and to the right of its spiral shell you will see two examples of their very strange looking egg casings. The moon snail secretes a mucus around its shell that has eggs layered inside. This mucus is immediately covered with sand resulting in a protective three-ply sandwich with the eggs wrapped in the inside layer! Spring and summer are good times to find these egg casings washed up on the beach; as long as they are not out of the water for too long the eggs will be fine. The white clamshell to the right of the moon snail shell is an example of their favored food. If you find a clam whose shell has a neatly countersunk hole in the top, you know you have founds remains of a moon snail meal! The moon snail has a radula; an anatomical ribbon with chitinous "teeth" that drills into the clam's shell, allowing the insides to be pulled into the moon snail's esophagus...everything in nature is smarter than we think it is, right!?!
Look for Moon snails and their eggs on your next beach combing adventure!!
I remember learning about the casings when I was in elementary school and never forgotten about it! Such a cool beach find!ReplyDelete