Those Fascinating Shells
By “Awake!” correspondent in the Philippines
IT HAPPENED in the year 1838 on the island of Bohol in the Philippines. The event nearly caused a British gentleman to faint with excitement. The man was Hugh Cumming, a conchologist, that is, a naturalist dealing with shells. On that occasion, Cumming found three shells known as Conus gloria-maris, meaning “Glory of the Sea.”
All that excitement over three seashells? Yes, indeed! Hugh Cumming had fulfilled a collector’s dream. Glory of the Sea is a rare, exquisite, and valuable variety of shell. Until 1965 only 25 of them had been found. A collection in the Philippines contains the largest one. Though fossilized, it can be worth, it is said, more than $1,000 (U.S.).
The Philippines is a shell collector’s paradise. Three of the 13 most valuable shells in the world come from this country. The publication Shells and the Philippines states: “By far the most fabulous for the diversity of its shell-bearing animals is the Indo-Pacific, a vast reach of water extending from the Red Sea and the eastern coast of Africa across the Indian Ocean, and into the Pacific beyond Hawaii and Easter Island. . . . But the center of this vast region and a mecca for shell collectors, is the Philippine Archipelago, with its thousands of islands, reefs, channels, bays, seas, and record offshore deeps.”
Where Do Shells Come From?
For the most part, shells serve as protection for mollusks, which are soft-bodied animals without bones. They include snails, clams, and oysters. Mollusks usually consist of internal organs, head, foot, and a skinlike mantle. The mantle secretes liquid material that becomes the shell. It forms in layers and is harder than glass. Cutting this substance calls for special tools.
No two shells are exactly alike. There is a basic hereditary pattern for each species, and environmental factors play a part. Color and adornment originate with special glands in the mantle. The largest living mollusk with an external shell is the giant clam (Tridacna gigas). It grows up to five feet (1.5 m) in length. However, fossil shells have been found measuring up to 15 feet (4.6 m).
Five Main Groups
Generally speaking, mollusks fall into five major classifications. One is Amphineura, a name that comes from Greek words that mean “around” and “nerve.” These mollusks have two nerve cords that go around the body. They produce a “coat-of-mail” shell that features eight overlapping shell plates held together by a tough girdle. The shell gets its name from its resemblance to ancient armor. Amphineura are docile creatures that creep over rocks to scrape off vegetation for food. Their only warlike trait is an excellent ability at camouflage.
The largest class of mollusks is Gastropoda, a name that comes from Greek words meaning “belly” and “foot.” They move about by means of a foot that extends beneath the body. There are some 50,000 species in this major group, including the distinguished Glory of the Sea. This class of mollusk also features snails, limpets, whelks, and slugs.
Gastropoda are called univalves, since they have only one shell. Perhaps you have noticed that snail shells have a spiral, or coiled, appearance. Most Gastropoda grow by winding in a clockwise direction, though a few coil to the left. Usually active, Gastropoda eat both vegetation and meat. If disturbed, they withdraw into their shells and close the “door,” which is a horny plate called the operculum.
Another class of mollusks is Pelecypoda, a name that comes from Greek words meaning “hatchet” and “foot.” They have a hatchet-shaped, muscular foot that serves as a means of locomotion. Mollusks of this class are known as bivalves because they have two matching shells. Clams, oysters, mussels, and scallops are familiar members of this group, of which about ten thousand species are known. All bivalves are vegetarians, and many of them make permanent homes by attaching themselves to rocks or by digging into the sand and mud.
A fourth class is Scaphopoda, from Greek words meaning “boat” and “foot.” There are about 350 species of this mollusk. They live in the ocean and have a pointed foot that looks something like a tiny boat. With this they burrow into sand, leaving one end of the shell pointing up into the water. Their body is covered by a single tubular shell open at both ends. Hence, many refer to them as “tooth,” or “tusk,” shells. Tentacles that extend through a small opening enable this creature to capture small organisms for food.
The fifth class may not readily be recognized as mollusks. They are called Cephalopoda, a name derived from two Greek words meaning “head” and “foot.” This class is distinguished by a number of tentacles (usually eight or ten) grouped around the head and the mouth. The squid, the octopus, and the cuttlefish belong to this group. However, among 800 species of Cephalopoda, only the chambered nautilus has an external shell.
Collecting Shells for Pleasure
Do you think that collecting shells would be enjoyable? If so, a good place to begin is the beach. Both shallows and shore hold many a beautiful shell. Do not let bad weather discourage you, as storms often litter beaches with a glittering array of shells.
Finding attractive ones, however, requires hard work. You must be willing to dig in the sand, examine grooves and holes, and search on tidal flats and in eelgrass. By swimming out a short distance and overturning dead coral and rocks, you may come upon a host of exotic discoveries. You can also find a variety of shells near rivers and on land. For instance, there are land and tree snails that exhibit gorgeous forms and hues.
But be careful! Some shells, such as the cone, conceal deadly, venomous mollusks. Certain ones are carnivorous and have five or six harpoonlike hypodermic needles with which to paralyze prey. They will strike indiscriminately at potential food or a human hand. The truth of this is underscored by recorded deaths of some shell collectors. Pick up cones in a net or in a container. Never hold them by the narrow end.
Careful, skillful cleaning will improve all your finds. Some methods are: boiling, soaking in lye, cleaning with bleach, chipping off encrusted material, and treating with hydrochloric acid. If you cannot remove all the meat by boiling or with a hook, or similar device, ants will often do a thorough job. After any treatment, especially the spot treatment with acid, wash the shells thoroughly in plain water. Now you have some splendid shells to display.
However, when thinking of cleaning shells, you must observe some don’ts. Never soak shells in acid. Avoid placing them in direct sunlight. And do not put thick shells in boiling water, as they may crack.
Mollusks exist worldwide. They may be found on the surface and in the depths of waters, as well as above and under the ground. For many individuals, collecting shells is a truly delightful hobby.
[Pictures on page 22, 23]