Seasidekrafts Sea Shell Facts

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How many different kinds of shells are there?

• There are between 50,000 and 200,000, species of mollusks, depending on who's doing the counting. These figures are based on the number of species that have been described, and which of those the count accepts as valid, and the estimates of the number of undiscovered and undescribed species remaining on earth.

Why are there so many different shapes of shells?

• Mollusks' shapes are a product of heredity combined with 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 -- best is a smooth and slender and gradually tapering shell, narrow end at the front, with no impeding projections, but mollusks have worked out many variations on this theme. 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 are also helpful for discouraging predators and, in some arrangements, for life on mud...broad weight distribution.