|abandoned seashell homes of mollusks. found on sanibel island, january, 2011.|
throughout time, these exquisite shells have had many uses. they have been utilized as art, jewelry, money, buttons, ink, road gravel, and in chicken feed (the calcium carbonate makes stronger egg shells).
the shells are created by secretions from the mantle, the part of the animal's body just under the shell. the mollusk shell is made of calcium carbonate and a little protein. there are no cells in a seashell. the animal's shell house needs to be constantly enlarged to accomodate growth. the shell grows from the bottom up; the newest part of the shell is around the opening where the little guy pokes out. with absolute precision, the shell is constantly added on to and repaired.*
the mollusks who originally inhabited these beautiful shell homes mostly float around in ocean currents, sometimes for hundreds of miles, or they scoot around on the ocean floor. they are eaten by other animals like starfish. some are taken by fishermen. others end up on the beach, and if they are not eaten or do not dry out in the sand, they will wash back out to sea and live another day. to most people mollusks are rather unattractive and sluglike, but once you get used to them i personally think they are cute. in january on sanibel there are more fighting conchs on the beach than people. it can get a tiny bit smelly at the trash line (made up not of garbage, but of mostly sea debris like seaweed, dead crabs and starfish, and thousands of living and empty shells at the high tide mark), especially after a storm.
three body parts are found in a mollusk: the head, the viseral mass, and the foot, which is the muscular end of the body. at the open end of a single shell mollusk (a univalve) the foot can pull in and seal the shell up tight, like a door, against predators. by closing the opening the mollusk also stays moist. without moisture the mollusk will die. this muscle also enables the mollusk to move. mollusks leap (florida fighting conchs are completely docile, but they can leap, so they can appear a bit aggressive, hence the name), hop, pull and dig into the sand.* what sturdy little creatures!
the japanese (who eat absolutely anything from the sea), the french (who love their tiny univalve periwinkle seafood), the italians (who have their specialty dish scungilli marinara made with knobbed whelk) and the caribbean islanders (whose delicacy is the meaty queen conch) seem to eat the most variety of univalve mollusks. if you able to deal with their looks and texture, almost all mollusks can be eaten, but some are tastier than others. of course the most popular ones are the yummy bivalves commonly found in restaurants: clams, mussels, and oysters. ed and i ate some of the biggest, freshest oysters we have ever had on sanibel. delicious!
*this information found in man and mollusc.net and oceanic research.org.