Since marine creatures are unfamiliar to many people, this section offers some detail about their life cycles and styles. It's useful to remember that minomers are the rule here. The blue crab is green; the horse-shoe crab isn't even a crab, zoologically speaking. But the mid-Atlantic beach wouldn't be the same without these critters. Here are some of the more common and visible ones: Blue Crab

When most people think "crab" they think of the fabulously edible blue crab, which is green on top with red-tipped claws and white and aqua highlights. A remarkably belligerent creature, it'll go for your toes underwater, perhaps because they look good to eat. Blues prefer brackish waters, though they can live in the ocean, home of their close cousin, the calico crab, which has a rounder shell mottled with pink and lavender dots.

Blue crabs mate in the fall at the time of the female's final molt. For a creature that will bite his sibling's claw off as soon as look at him, it has a surprisingly tender mating ritual. An amorous male literally carries his chosen mate through the water, cradling her beneath him until she casts her shell. (Insemination is impossible through the shell.) In the spring the eggs emerge in a spongy orange mass from the bottom of her shell - the part called the "apron" by diners and "abdomen" by biologists. By either name, this structure is nearly semicircular in the female and narrowly pointed in the male. In the early summer many dead females wash up on the beach with the spent egg masses attached. The tiny larvae go through several weird looking stages and apparently make long, unwilling migrations at the whim of the currents before starting to resemble their parents. Spider Crab

This may be the most lethargic and impersonable of the entire family - or so I thought until I met Alta VanLandingham, the shell seller of Ocracoke. "Lady," her pet, runs to the near corner of the aquarium when her mistress enters the room. This spider crab, with long legs and round body, delicately scampers over rocks or mollusks and clings to the woman's fingers.

Spider crabs are commonly found on beaches - tangled in surf rows of seaweed or lost nets - where they seem like sluggards. It may simply be because they're dying for water; they recover quickly when put back in the wash.

The spider crab is talented in its fashion. It uses camouflage to conceal itself on the sea bottom. Whether for defensive or offensive reasons, they take bits of algae, like sea lettuce or eel grass, and glue it to their backs with a special secretion. The algae will grow there until the crab looks like a local rock. Hermit Crab

Not a true crab, this decapod begins life as a free-swimming larva and after several molts takes its curiously asymmetrical appearance. The naked adult looks something like a small lobster gone wrong with one claw twice the length of the other and a sharply curved, lopsided tail. But it is rarely seen without a borrowed shell.

A soft-bodied creature, it resides in the castoff shells of mollusks and gastropods - starting typically with a barnacle's husk and moving up throug the periwinkles and snails as it grows larger. Horseshore Crab

This is an arachnid, member of a catchall zoological class that includes spiders, scorpions, ticks and mites - which are distant kin. Limulus polyphemus has outlived all its close relations and survived unchanged for some 200 million years to earn the unquestioned title of "living fossil."

The ponderous crab looks vaguely like a rusty antique helmet with a plate to guard the nape of some Tartar neck and a sharp spike hanging out aft. That's not a weapon; it's the only tool this beast has to right itself when capsized (a common enough occurrence, no doubt, over the millenia).

Coming ashore only to breed, the animal lives on the ocean floor, often rumaging around the surf zone. While they can startle an unsuspecting wader by moving underfoot, they're not known to attack anything much larger than a worm. In effect they're totally harmless to man and very familiar because their shells litter many ocean beaches. Most of the shells are discarded husks, not corpses.

Live horseshoe (or king) crabs are first seen in May or June when they start coming ashore to breed. A female may return ten times a sea-son - as late as early winter. She scrapes out a depression in the sand and lays 1000 eggs at a crack with her smaller mate in tow, literally, semipiggyback style. She drags him across the nest while he deposits the sperm; the next tide covers it all with fresh sand. When the eggs hatch some weeks later, the tailless young crawl out and head for the shallows.

The horseshoe crab is as bizarre in action as in appearance. For example, it cannot eat while sitting still; its mouth is located between its five pairs of walking legs which have special spines that gring up the worms it pulls from seabottom burrows with tweezer-like pincers. But if it lacks table manners by eating on the run - or crawl -it is a certified blueblood. Its blood has a blue tint because it contains copper instead of iron to carry the oxygen. Crustacea and most mollusks share this trait. Mole Crab

Another misnamed inhabitant of the littoral zone is the mole crab. This inch-long untrue crab is gregarious.Seldom found singly, it and its associates gather in shoals of thousands where waves break.

They migrate up and down the wet sand, always staying in the active wash of the waves, scurrying around the shallow surf like minute armadillos. As the water from one wave recedes they burrow down in the sand, often disappearing until after next wave has passed. This is how they feed. Avoiding the crush of the breaking wave, they emerge to bury themselves bottom-first in the wet sand and extend long, ornate antennas which filter plankton from the receding water. They are a key link in the food chain - a major connection between plankton and larger animals.

They are very easy to catch in a hat or hand. Absolutely harmless - they tickle your palms while burrowing in a handful of wet sand - they're good momentary pets for small children, especially squeamish tots who are normally afraid of animals. Shaped rather like moles, they behave more like tiny terrified bunnies. Ghost Crab

A true crab, it has largely left the water to live in the dry dunes above high tide (but must return to the shallow wash several times a day to wet its gills). These white or tan creatures are very fast runners that scurry down their deep round burrows at the drop of a human football. To study them closer, sit still for a few minutes where their holes and tracks are plentiful - they'll soon go about their skittering business. Or return at night with a flashlight when they own the beach. Shells

On an Atlantic beach just after World War II three boys engaged in what an English writer calls "the gentle art of wrecking." That means to go to see what the tide dragged in and lug it home for fun or profit. Farmers used to harvest rockweed fertilizer that way. People with metal detectors now do it in search of Spanish gold but settle for lost loose change and car keys. Some hope for random flotsam (wrecked ships or cargo) and jetsam (stuff thrown overboard to lighten a foundering vessel.)

Looking for absolutely anything, my friends and I found a large waterlogged crate on the empty beach.Its stenciled letters indicated war material - treasure of the highest price to kids whose generation barely knew peace and yearned to be fighting men when we grew up. We worked cautiously, with pocketknives and driftwood levers, in case the crate contained hand grenades for the French Resistance. But we worked with zeal for it might hold bayonets or bullion for some fifth column. The job took hours; we had to move the leaden thing twice from the returning tide. When the lid finally came off our treasure was this: one thousand gross cartons of matchbooks destined for troops closer to the rear than the front. The covers had two or three different cartoons - of hussies leaning against lampposts - but the legends were all the same: "GI Joe Knows VD Can Be Prevented." We knew wet matches wouldn't light grapeleaf cigarettes and we decided that military life wasn't as good as it had seemed.

But I never gave up assiduous wrecking. In the quarter century since, I have found telephone line reels, two whale skeletons, one recently deceased porpoise, three loggerhead turtles, a Chevrolet, a tricycle, enough bleach bottles to launder the Sixth Fleet, one sixteen-foot sailboat, uncounted pieces of wooden hulls, iron ship nails in worm-eaten keels, a yard of oyster-encrusted cable that looked like a sea snake, more barrels than a delicatessen, one squeeze bottle of Spanish pomade, innumerable fishnet floats, airplane fuel tanks, one anchor chain, miles of hawser and half a catamaran. I left most of it where I found it, except some of the bones. I have never found another sealed crate nor anything closer to a piece-of-eight than a sand dollar. But I kick those dead echinoderms aside and keep on looking.

Many people are content with shells, starfish and the skate's black egg case which is known as the devil's pocketbook (or sailor's purse because it always comes ashore empty). I envy folks with such simple acquisitive drives and have stopped explaining why there's a whale vertebra in my hall. But guests understand the bowl of shells on the coffee table and finger them like worry beads. That heap evokes the unspeakable mysteries of the ocean and its eternal, infinite designs. Shells may be the most sensible things in the world to save. Easily handled and carried, they're clean, light, no trouble to preserve, more varied than a herd of Pet Rocks and free. They have nice names too: little white trivia, fighting conch, greedy dove, strawberry cockle, Humphrey's wentletrap.

Most washed-up shells are the last earthly remains of their creators. But some contain a meal. Whelks commonly wash ashore with the tasty critter still alive inside. Clams are easily dug or even found stranded by a low spring tide that drained the sands before they could hide.

The largest phylum in the animal kingdom is the arthropods which includes crabs, lobsters, insects, barnacles, shrimps, water fleas, horseshoe crabs, spiders, pseudoscorpions, etc. The second largest is the molusks, descendants of a common ancestor that died off 600 million years ago. Hence they have had time to evolve a vast array of varieties. An escargot is one mollusk in garlic and butler. A seventy-five-foot squid is another.

Mollusk comes from the Latin molis, meaning soft, and was reputedly coined by the Greek Aristotle who had in mind the sea hares and squids. Comparative anatomists expanded the category but still haven't answered all the questions. (A gastropod's spiral shell is right- or left-handed. It is not yet known whether all shells that are mirror images of each other belong to distinct species or result from some genetic fluke - a typo in the DNA.) Nonetheless, the phylum possesses two zoologically unique structures: the mantle, a fold in the body wall that secrets the shell; and the radula, a ribbon-like tongue covered with a few hundred tiny rasplike teeth. Ambulatory mollusks have a large muscle to walk on, the foot.

They are all "oviparous or ovoviviparous; that is, they lay eggs, or, laying eggs, they retain them within their shells until the young are hatched out." The delicate lavender hermaphrodite janthina, which Clay Gifford finds on the Outer Banks, builds a raft of gelatinous bubbles and floats around the open ocean surface with its eggs awash. The distinctly female Scotch bonnet lays a tower of eggs as round as herself and taller.

One difference between northern and southern beaches is that above Hatteras they're largely sand while below they contain more and more carbonate - which is crushed seashells and coral. Mollusks seem more varied and numerous in southern waters, but there are plenty to go around on the mid-Atlantic beach:

The Atlantic deep sea scallop which ranges offshore from Labrador to North Carolina, is one of the drabbest of its multicolored kind. Its rough tan or brown shell is strengthened against predtory fish by raised ribs. Unlike most of its relatives, this bivalve cannot bury itself in the bottom. But it can swim by snapping its valves (shells) together - a form of jet propulsion. Some sea scallops have 100 eyes along the edge of the mantle.

Coguina clams belong to the Donax family. While a southern species grows half an inch long, those in our latitudes are usually half that size - tiny pastel triangles that may number 1600 individuals in a square foot of wet beach. Living in the tidal wash, they move up and down the sand, migrating with the tide to stay in the ideal part of the wet zone.

The Eastern oyster grows from New Brunswick to the Gulf of Mexico and is choice food for humans and other mollusks alike. The dozen appetizers on your plate represent all the adult offspring of a single individual that laid 50 million eggs two or three years ago. Curiously, the adults change sex from time to time. Egg production in a female pro tem is triggered by rising water temperature and hormones from free-swimming sperm. The eggs hatch into larvae which swim for some time. Then metamorphosis intervenes, and they crawl about on a small foot. Finally the crawler glues itself to a selected object - usually a cousin - and takes up residence there for life.

Surf clams are ubiquitous; two dozen species inhabit American waters. The Atlantic surf clam, which gets shredded up for fried clam rolls, is the largest off this coast and grows to six or seven inches. It lives on sandy bottoms as much as 100 feet beneath the ocean's surface. The softshell clam belongs to another zoological family. It lives buried in shallow, muddy bottoms - more out of its shell than in it unless threatened - with the tips of its siphons exposed.

Jackknife clams are the longest members of the razor family. Good swimmers, they are also capable diggers. When frightened they bury themselves with amazing speed and strength. Beware of pulling them out with your hands because the narrow edges of their shells are as sharp as their name implies.

Two species of mussels are common along the East Coast, the blue and the ribbed. Both attach themselves to the bottom with a series of anchor lines which they manufacture and secure with the foot. When one byssus breaks others are spun and set to replace it. With several of these moorings, the animal is secure in a strong current flowing from any direction because the shell turns like a wind vane to present its narrowest edge. The blue mussel, which is sedentary but not permanently fixed, prefers hard surfaces like rocks, shells and pilings in active water. The ribbed mussel lives half-buried in mud flats and isn't nearly as tasty as a result.

The northern quahog has many aliases: littleneck, cherrystone, hardshell and round clam.Zoologists admire the efficient anatomical design, which is exceptionally hard and strong without being ponderously heavy and contains ample space inside.

Three species of whelks are common along this coast: channeled, knobbed and lightning. They are responsible for the necklace-like strands of egg cases that lie tangled on the littoral. Each capsule contains as many as 100 miniature whelks, but a portion of these never grow up. They serve as "nursery eggs" for their hungrier siblings. As adults these gastropods (snails) turn their voracity on the bivalves. Gripping a clam with a strong foot, the whelk clutches the clam's seam against the lip of its own shell in a fatal embrace unitl the victim opens. Atla VanLandingham has seen a whelk pound clams open against itself and, after eating, bury itself in the aquarium gravel until its own chipped shell heals.

A moon snail may eat four or five clams a day. Digging through the sand, this smoothie holds its victim still and drills a neat, small hole in its prey's shell with its radula lubricated by acid from a special gland. The snail's eggs are contained in the familiar and fragile sand collar which takes the shape of their shell's interior.