THE SHELL AS AN ARCHITECT. . .HOW DOES HE DO IT?
Picture a vast undersea factory with billions of shells in constant production. Each is made slowly and entirely of lime which the little animal inside extracts from its food, almost from the first day of its life. Each shell builder flawlessly follows the shape and design of the species to which it belongs.
All these sea animals come from eggs, all different according to species, but all laid in measureless abundance—sometimes released into the open sea, sometimes protected in homemade nests, sometimes encased in capsules strung like beads. Hatched, most baby mollusks swim freely for a while, their tiny, transparent bodies almost invisible to the naked eye. Then they start building a heavier shell and sink to the bottom.
Each shell's mantle contains a network of microscopic tubes. Each tube secretes a tiny amount of lime which instantly adheres to the shell. The animal builds his shell to the proper size and thickness and determines its ridges and whorls. Some kinds of shells take two to five years to reach maturity. Others keep growing all their lives. Color tubes are spaced like holes on a player piano roll allowing pigments to tint the shell at the right spots in the growing design. Many shells are covered with a self-made brown sheath, the PERIOSTRACUM.
[figure captions]
Most shells don't change basic structure as they grow. Young
COWRIES (l.), however, alter greatly in maturity (r.).
Tough, lozenge-shaped egg cases on this string hatch baby WHELKS like ones shown.
Newborn mollusks are usually free swimming, moved by hairs. Shell is there, but transparent for a few days.
LET'S MEET SOME SHELLS
Latin abounds in conchology, as you've already noticed. Why? Well, because this is a hobby and science that spans the world. Englishmen, Frenchmen, Greeks and Indians all have their own local names for shells. But scientists everywhere give things in nature Latin names. Shells of the same sort carry the same Latin label on every beach in every sea. Much of the fascination of shell collecting is learning these names and how they were derived. . . for shells have been named for almost everything. We can't catalog 100,000 species here, but let's call off the names of a few of the interesting specimens you might come across.