Here are a few interesting facts about the world’s seashells:
How many different kinds of seashells are there?
There are somewhere between 50,000 and 200,000, species of mollusks which have a shell. The exact number depending on who’s counting. These figures are based on the number of species that have been described, which of those are accepted as valid, plus the estimates of undiscovered species remaining on earth.
Why so many different shapes of seashells?
The shape of a Mollusk is a product of heredity, habitat, and life style for the most part. Shell shapes have evolved to make their lives easier. A snail that burrows through sand needs a shell that will move through wet sand easily.
Other mollusks have worked out variations on this. A shell that needs lots of camouflage may have evolved a spiny or irregular surface which will catch and hold all sorts of camouflaging encrusting organisms. Spines also serve to discourage predators.
How big do shells get?
The largest known marine snail is Syrinx aruanus, the Australian Trumpet, measuring up to 35.8 inches long and weighing up to 39.6 pounds.
The biggest American marine snail, the Horse Conch, Pleuroploca gigantea, is just over 24 inches. The world’s biggest clam is of course the reknowned Giant Clam of the southwest Pacific, Tridacna gigas. The largest specimen reported in the scientific literature was an unbelievable 4.5 feet long from one end of its shell to the other (Rosewater 1965), certainly making it the largest species of clam in the seas. This specimen isn’t the record holder for weight though, as a somewhat shorter gigas weighed in at 734 pounds (Knop 1996). Thus, gigas is the heaviest clam, too.