Lets Collect Rocks and Shells | Page 2

creating ingenious camouflage.
It builds its calcareous house with a great instinctive talent for color
and sculpture. . .and the closer it lives to the tropical zones, the more
beautifully spectacular is its art.
The two parts of a bivalve shell are like thin saucers, concave inside,
convex outside. The inside is smooth, polished. The outside is rougher,

sometimes with graceful ribs or concentric ridges or combinations of
both. Univalves are conical and spiraling, with a series of whorls
coming down like widening steps from the tiny nucleus on top.
Univalves may have spines on their shoulders. The opening, called the
aperture, has a delicate right-hand rim called the lip and a heavy,
left-hand edge called the columella.
[figure captions]
BIVALVE'S anatomy: a) foot, b) adductor muscles, c) gills, d) hinge, e)
adductor muscles, f) siphon, g) stomach, h) mantle. Oysters, clams,
mussels all have them.
UNIVALVE'S anatomy: As before, a) foot, b) siphon, c) mantle, but
also d) operculum. Univalves include whelks, winkles, conchs.
Chambered nautilus is brother to the octopus, but he wears his castle
permanently--and on the outside.

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.
Many shells have wonderfully descriptive names. For example, there's
ARCA ZEBRA, which has stripes and looks like a miniature turkey
wing and is commonly called Turkey Wing. Then there's a scallop
called the Lion's Paw; NERITA PELORONTA, or Bleeding Tooth; and
CYPRAEA CERVINETTA, "little deer cowrie" which resembles a
spotted fawn. (Cowrie is a common name for a kind of shell used as
money in parts of Africa and Asia.)
There are shells named for people: CONUS JULIAE ("Julia's cone
shell"), PLEUROTOMELLA JEFFREYSII ("Jeffrey's Pleurotomella"),
and ACLIS WALLERI ("Waller's Aclis"). Many are named for the
place they were first discovered: UROSALPINX TAMPAENSIS,
Tampa Drill; and IPHIGENIA BRASILIANA, Brazil Clam.
Some shells take their names from flowers: FASCIOLARIA TULIPA,
Tulip Shell. Many get named from mammals--not always too
accurately. CYPRAEA TIGRIS and CYPRAEA ZEBRA both have
spots, not stripes. But CYPRAEA TALPA ("mole cowrie") does look a
lot like a mole. Then there's (let's skip the Latin this time) Magpie Shell,
Mottled Dove Shell, Mouse Cone, Horse Conch, Checkered Pheasant,

and Cuban Frog Shell. There's mythology: Venus, Neptunea, Pandora,
Tritonis. Music: Buccinum ("trumpet"), Citharas ("guitar"), Harpa.
Religion is represented, too. In the genus MITRA are species
PONTIFICALIS, EPISCOPALIS, PAPALIS, and PATRIARCHALIS.
Some other fanciful names are: Great Heart, Jewel, Box, Rising Sun,
Checkerboard, Wood Louse, Writhing Shell, Sundial, Key-Hole
Limpet, Red Turban, and Black Lace Murex. And that's where we stop
and