American Lobster (Homarus Americanus) has the general form of the crawfish, heretofore described, but may be distinguished by its larger size, marine habitat, narrow and spiny rostrum, and greatly developed anterior claws. The rostrum is sharp, turned up at the point, furnished with spines at the base, on the sides, and beneath, and with a slight furrow on the dorsal surface. The shell, which is olive or blackish green with darker spots and blotches, as is well known, becomes red by boiling, from the action of the heat upon its pigmentary matter; acids and alcohol produce a similar effect, but all in a manner not perfectly understood, except by the further oxidation of the coloring matter. This horny, mahy-jointed, external skeleton, being non-extensile, is changed periodically as the animal grows; it splits in two on the head and body, the new one forming underneath in two equal halves, the tail being shed without splitting; in this condition of the shell, which is soft as paper, the animal is defenceless, and hides in crevices in the rocks to escape destruction by voracious fishes and its own species.
The eyes are placed on the end of two peduncles, movably inserted on the anterior border of the head; the external antennae are very long and many-jointed, the seat of a delicate sense of touch, and at their base is a hollow process supposed to be the seat of the sense of hearing; there is also a pair of smaller median antennae, in whose basal joint is generally placed the sense of smell. The first three segments of the thorax are changed into oral and tactile organs, forming foot jaws around the mouth; beneath a soft upper lip is a pair of strong mandibles moving laterally, the internal border hard, and having a tactile palpus; behind these mandibles are two pairs of lower jaws, weaker, and without tactile appendages; both mandibles and maxillae are mere processes from the basal joint of thoracic legs; between these organs is a soft under lip. which is a fold of the skin. There is no distinction between head and thorax, the anterior part of the body being called cephalotho-rax, which contains 14 segments; the first six contain the eyes, antennae, and jaws; the next three bear the maxillipeds or jaw feet; the 10th segment bears the great pincers, used as prehensile organs, ending in a two-fingered organ, the metatarsus being thickened and immovable and the tarsus capable of being applied to it like a finger; the four succeeding segments bear the ambulatory feet, consisting of six joints each, the anterior two pairs ending in weak pincers, and the posterior pairs with a single point, all more or less hairy.
The abdomen consists of seven segments, with six pairs of natatory appendages beneath, some concerned in the function of reproduction, and the terminal one divided into five hair-fringed plates, the external ones jointed. According to Siebold, the thorax is entirely abortive, the five pairs of legs being appendages of the abdominal segments. The principal organ of locomotion is the tail, which, by a sudden bending underneath, sends the animal backward with great velocity. The carapace is free at the side, and has a transverse suture on the back, the last segment being immovable; the abdomen is about as long as or longer than the thorax. The intestine is straight, and the anus at the end of the tail; the stomach has a firm cartilaginous support in the pyloric portion, consisting of three solid movable pieces, called the "lady" from a fancied resemblance to a female figure seated upon a sofa; it is composed of chitine, studded with bristles, and its parts doubtless serve the purpose of teeth in an internal mastication; the cartilaginous framework is shed with the external skeleton. There is a greenish glandular organ surrounding the intestine, with a mixture of fat cells; this, popularly called "torn alley," is the liver.
There is a distinct heart, with well developed arterial vessels, but the blood does not flow through capillaries into veins, being effused into the lacunae which lie between the organs and appendages of the body; still the blood moves in a determinate direction, assisted by venous sinuses. Respiration is aquatic, effected by branchiae, 19 in number on each side, covered by the carapace, and enclosed in a special cavity at the base of the thoracic limbs, communicating externally by two fissures; the water enters at the base of the feet near the edge of the cephalothorax, and passes out on the sides of the respiratory organs, which consist of clusters of minute cylinders set together in a brush-like manner; the foot jaws have also branchiae. The sexes are distinct. The eggs or berries of the lobster are reddish or blackish, spherical, glued together by a viscid matter, and attached in clusters to the hairy feet of the posterior abdominal segments; they are thus borne about, protected under the body of the female, until the embryos are fully developed. The young differ but little from the adults, and take shelter under the mother's tail; they are often seen surrounded by the young 6 in. long, which retire to safe retreats when apprised of danger by the mother.
One of the most curious peculiarities of the lobster is the ease and frequency with which the large claws are separated, either by accident or from injury received in their constant attacks upon each other; these and the other limbs are very soon replaced, and it is very common to catch these animals with one claw absent or smaller than its fellow; they are said frequently to lose them after a heavy clap of thunder, at which they are always much disturbed. As the teeth of one large claw are numerous and sharp, and those of the other few and blunt tubercles, the uses are probably different, the one for crushing and the other for retaining food or crippling an enemy; they are very quarrelsome, whether free or in captivity, and are dangerous to handle for those unacquainted with their habits and mode of attack. They come in shore from deep water from March to May according to locality, and depart as irregularly in the autumn. They move rapidly in their migrations, in solid column, the largest and strongest in advance, the smaller and weaker bringing up the rear, and then scatter over their favorite feeding grounds, devouring clams, mussels, and other mollusks.
They vary in length, as caught for the market, from 1 to 2 ft., though specimens are seen considerably larger than this, and in weight from 2 to 15 lbs.; they are common in the markets, especially in spring and summer, and are considered a great delicacy, though the meat is rather indigestible. There is only one species in our waters, found from the coast of New York northward; the best are taken on the rocky shores of New England north of Cape Cod; our species is distinct from H. gammarus (Milne-Edwards) of Europe, and grows to a larger size. Their food is entirely animal. They are caught in baskets or traps, with a concave netting at each end having a hole in the centre, and baited with dead fish or any garbage; they can enter easily, but their expanded claws prevent egress, on the principle of the common wire rat trap. These traps, sunk to the bottom in deep water, and their places marked by wooden floats, are raised every day or two, and their contents removed; to prevent their injuring each other, a wooden plug is driven into the joint of the movable thumb, which keeps the claw shut, and they are then transferred to a large floating car, in which they will live many days, until they are wanted for market. The limit of salable size in Massachusetts is at all seasons 10 1/2 inches.
It would be impossible to estimate the number consumed annually in the fresh state, but it must be counted by hundreds of thousands; as the price varies from 3 to 6 cents a pound, at the lowest, it will be seen that the lobster fishery is a source of a very great revenue to New England, which is their principal habitat and market. The shortest way of killing them is breaking off the rostrum. They are considered as good only for bait while undergoing the change of the shell; no part is poisonous, though the cartilaginous stomach or "lady " is so tough that no one would think of eating it; like other crustaceans and shell fish, they sometimes cause eruptions of the skin in hot weather and in susceptible constitutions; the unimpregnated eggs, of a fine red color, commonly called " coral," are considered a delicacy. For further details on the habits of the lobster, see Prof. Verrill's " Report on the Invertebrate Animals of Vineyard Sound and adjacent Waters" (Washington, 1873). - The genus palinurus (Fabr.), or spiny lobster, of the European seas, grows to a weight of 15 or 20 lbs.; the shell is hard and spiny, the antennae are much longer than the body, and the claws are very small; it is much esteemed as food, and was prized by the ancient Romans, who called it locusta.