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The fearsome octopus, sometimes called "devilfish," since early times, has engendered terrifying legends based more often on fancy than fact. They are among the largest, strongest, fastest, most cunning, and ferocious of all animals. Most of them, however, are quite harmless and are useful in a variety of ways.
For the scientific reader, they are members of the phylum Mollusca (clams), class Cephalopoda (squid, nautilus and octopi), order, Octopoda. About 50 different kinds of octopuses are distributed throughout the oceans of the world in tropical and warm temperate waters. Most off the east and west coasts of North America have bodies only three or four inches long, with short arms about as long as the body. The largest, found off Puget Sound (off the state of Washington) may reach as much as 50 ft.
The octopus dwells on the ocean bottom in shallow waters where it crawls about on its arms, searching in every crevice for its favorite food of shrimps, crabs, and mussels. It is a skillful hunter and attacks such large prey as sharks and dogfish. Sometimes the octopus lures his prey by wiggling the tip of an arm like a worm. Other times it stalks a victim until it can drop down on it from above. Then wrapping the arms around it, and with suckers firmly attached, it drags the prey into its powerful jaws.
It is the terror of pearl divers in Asian waters, where it has been known to hold a man down until he drowns. If the octopus is losing the battle it shoots out a cloud of black ink and hastily retreats. It may lose one or more arms in the fight, but they are soon replaced. Its worst enemies are the savage conger and moray eels. When attacked, the octopus draws water into its mantle cavity and expels it with great force through a funnel, making a jet-propelled exit, usually behind a cloud of ink, a dark substance the octopus ejects for defense.
The creature can change color to match its surroundings. Over the animal flow waves of color--gray, brown, pink, blue, green, perhaps even an angry red if it is suddenly frightened. It may move over the bottom of an aquarium tank on the tips of its arms as delicately poised and graceful as a ballet dancer. One has the impression of a soft, flexible creature in constant, controlled motion.
It is a shy, antisocial creature, living alone in a rocky den. Sometimes it digs its own den, moving stones of considerable size and closing the entrance with stones when it retreats inside. The animal spends much of its life hiding, choosing a natural hole among rocks, or, if small, an empty clamshell he can pull shut with his suckers.
Octopuses are the most highly developed and intelligent of the animals without backbones, or invertebrates. They have a distinct head, with brain. The large, lidless, unblinking eyes resemble those of human beings and are totally unlike those of any other invertebrate. The two large, complex eyes give the octopus acute vision.
Most octopi are carnivorous. They catch their prey with the arms and transfer it to their mouth located on the underside, inside the circle of the arms. A ring-shaped lip surrounds the mouth. Inside the lip is a sharp, parrot-like beak. In the throat are the tongue and radula. The radula is a sharp, horny ribbon that lies on the upper surface of the tongue. As the tongue moves back and forth, chunks of food are ground to bits.
The arms are lined with a double row of suckers for the entire length of the inner surface. Those of the octopods are attached directly by the base to the arm whereas in the squid the suckers are raised on short stalks. Each sucker ends in a horny ring that in some species is also saw-toothed.
Octopuses reproduce sexually. With one arm, the male grasps a sperm capsule from its funnel opening and transfers it to the mantle cavity of the female, also known as the hen. In certain octopuses the arm becomes detached and remains for a time in the female's mantle cavity. A new arm grows to take its place. Soon after mating the female lays eggs, each enclosed in a transparent capsule, producing about 150,000 in two weeks. The eggs are hidden under rocks or in holes and are laid either singly or in grape-like clusters, depending on the species. She guards them, jetting water to aerate and clean them, until the eggs hatch into a small form of the adult in four to eight weeks. The young are then on their own. Some species float to the surface, becoming part of the plankton for about a month, then sink and begin their normal life on the bottom.
The octopus has some commercial value in south Europe, Asia and many other parts of the world where it is a food item. Sepia ink however, is usually derived from squid, which are both more abundant and easier to catch. Another commercial use is in the scientific study of their ability to regenerate arms (legs?) Once the mechanism is solved it might be useful to apply to man himself.
As for threats to man. Although the octopus has occasionally known to grab a diver, holding them under until they drown, this is unusual since they are normally painfully shy and usually quite small while mildly curious. One should be aware however, that all octopi do have poisonous bites and will at least cause some irritation. There are only a few that are dangerously venomous. The major threatening species is the blue-ringed octopus, which plagues the Australian coast and Indonesia. This one can deliver a fatal bite. Death occurs by a rapid onset of paralysis with breathing difficulty.
References: Compton’s Multimedia Encyclopedia, Encarta Multimedia Encyclopedia
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