Friday, May 11, 2012
HOW DOES A MOONSNAIL EAT?
Moonsnails, a quite large, carnivorous snail found locally, Apparently, they are great in chowder, but not so much pan fried. I was on the beach with some fabulous Beach Naturalists and a couple of questions arose: 1) how do they eat? 2) how do they move--like, what good is all of that slimy stuff? I will work on the eating part in this post.
Moonsnails eat all types of clams but they demonstrate a strong preference for our native littleneck clams. These clams live several inches down in the sand, and the moonsnail has become very efficient at digging for them. First it thrusts part of its big, slimy foot into the sand, inflates the "anchor" with water, then pulls itself into the sand. It keeps doing this until it reaches the clam, then armageddon ensues, at least for the clam.
Upon reaching the clam, the moonsail enfolds the clam in its foot, manipulating the clam as needed. Moonsnails get at the clam in a couple of different ways: drilling or creating a gap
To drill, the moonsnail manipulates the clam so that its hinged side is close to the snail's mouth. Once the clam is in position, the moonsnail uses an "accessory boring organ" that exudes carbonic anydrate (acid) to soften the shell so that the moonsnail's raspy tongue can drill a hole in the shell and the clam can be eatedn from the inside out. There is mention of a frankenstein-ish approach wherein the moonsnail sucks the clam out through its own siphon, but just a mention.
Drilling is a lot of work, however. It's much easier if the moonsnail just wraps its foot around the clam, encases it in foot mucus, and then waits for the clam to suffocate, thereby crating a "gap" in the shell through which the moonsnail can enter. Researchers who actually study this stuff (kinda like watching grass grow) report that it is not unusual for a moonsnail not to drill, but to suffocate. Even better if a gaper clam has been chosen for dinner--the gap gives the moonsnail a natural "in" whereby it can simply insert its radula and begin hacking away at the clam--no suffocation needed.
Contributed by Gretchen Frankenstein