Page:The New International Encyclopædia 1st ed. v. 12.djvu/421

LOBSTER. nun., four pairs of suiuuiicrets have appeared, ami in tiie tliirj stage the last pair of abdominal legs (uropodsj arise. This stage lasts from two to eight days, its body being 11.1 mm. in length.

In Xarragausett Bay (ickford) the average period for hatching and reaching the fourth stage was a little over twelve days. The length of the fourth stage varies from 10 to I'J days; and during this period the larva is about halfan inch (12.3 mm.) in length.

After the third molt, the young lobister or lobstcrling (Fig. 4) assumes the shape and habits of the adult. Its body becomes heavier, the chelte or hands of the first pair of feet are held straight out, and after living at the surface from six to eight weeks it sinks to the bottom, over which it crawls, and now the habits change. The joung lolj.ster, pre- viously without fear and moving aimlessly about at the surface, now appears timid and retreats from danger, as docs the adult: after reaching the bottom it travels toward the shore, and burrows in the sand at the bottom under stones, and takes every precaution to avoid its "enemies,' Its nat- ural food consists of minute crustaceans (cope- pods), and when food is scarce its own breth- ren, as it is atrociously cannibalistic. JIoLTiNG. The periodical shedding of the skin begins when the lobsterlings are two or three days old, and continues throughout life, the intervals between the successive castings of the sliell gi-owing longer with age. It molts from 14 to 17 times during the first year of its life. After sexual maturity ecdysis may hot occur more than once a year; a lOlo-inch lobster has molted from 25 to 26 times.

In the first molts, as in those succeeding, the process is the same, the old skin being split across the back, between the hinder edge of the shield or carapace and the abdomen; the carapace is raised up behind, the body being gradually drawn out through the gaping opening. In adult lob- -rers the withdrawal of the contents of the big (laws is facilitated by the partial absorption of the lime in the shell of the narrow pari of the base of the leg, so that the integument can be distended. The muscles at this time are greatly stretched, while their action is probably aided by the removal of water from the blood (Vitzou), During the process the stomach with the solid teeth, as Avell as the chitinous lining of the oesophagus and intestine, are cast off with the entire integument, including the finest hairs fringing the appendages. 'Shedders' are those with shells 'hard and dull,' previous to shedding or casting their shell, while soft-shelled lobsters are those which have recently exuviated. The process occupies but a few minutes, unless through weakness it is delayed. The period of shedding is. as in insects and other animals, a precarious one. and sometimes the animal dies during the process; both in the larval and adult stages growth or increase in size takes place while the new shell is being formed, and not immediately after ecdysis. (Herrick.) The in- crease in length of a lobster five and one-half inches long is one inch: in one llVj inches long one and one-fourth inches. The appearance of sudden growth is due to the absorption of water, not cellular growth. After molting it is several weeks before the new shell is as hard as the old one.

Kate of Cuowtu. Uur knuuiLii-u of liie rale of growth of lobsters is not dclinite, but it is known that this rate varies enormously in dif- ferent individuals reared in confinement in the same car under apparently the same conditions. Lobsterlings of the same age will measure from two and three-fourths to five inches. It is prob- able that the length of nine inches is not usually attained before the third year. The variations in growth are so great that "it will never be pcjssible to tell the age of a large lobster from its length." A 10^4-inch lobster is about five years old.

The problem of artificial propagation of the lobster will be solved, says Herrick, when means are devised by which the larvae alter hatching can be reared in large inclosures uutil the fifth or si.xth stage, i.e. when three-quarters of an inch long, and able to take care of themselves. Ecoxoiiic lMPORT.i.NCE. Of the annual yield of lobsters on the Atlantic Coast of the United States, 75 per cent, is from the waters of In 1880 the total yield of the United States was over 20 million "pounds, and in 1889 this had risen to over .30 million, but that was the high-water mark of lobster production. Beginning with 1890 there has been a constant decrease in the amount, so that in 1898 it was only a little over 15 million pounds, and in 1900 still less. But while there has been this immense decrease in amount, the ever increasing demand has steadily raised the price, so that the value of the catch in 1898 was more than $1,300,000, while in 1889 it was about .$860,000. In ISSO the Massachusetts catch was over 4.300,000 pounds, worth about $158,000, or about 3.6 cents per pound; in 1898 it had fallen to less than 1,700,000 pounds, worth less than $148,000, or about 8.7 cents per pound. Strenuous eft'orts have been made to prevent the extermination of the lobsters and to replenish the depleted areas, but so far with little success. All the Xew England States have laws protecting small lobsters, but these laws vary somewhat in the different Stales and are difficult to enforce. The principal feature of these laws is the determination of the minimum size of a marketable lobster, measured from the anterior end of the head (the so-called beak or rostrum) to the tip of the telson. None of the States permit the sale of lob.sters less than nine inches in length, and the ^Massachusetts law places the limit at lOt^ inches. In addition to protective legislation, attempts have been made to save the lobster-supply by artificial hatching and planting of the young. These efl'orts have been made chielly by the United States Fish Commission, which has for some years past secured all the females "in berry' which were obtainable, and, taking the eggs from them, has raised them under artificial conditions, as is done with fish-eggs. In 1900 more than 90,000,000 eggs were thus handled, from which over 80,000,000 young hatched. Unfortunately, however, these attempts have not met with any considerable success, as the young in the hatcheries have a vei-y high death-rate, owing to the attacks of p.irasitic diatoms and bacteria. In 1901 and 1902. however, more encouraging results were obtained than ever liefore, through the use of large bolting-cloth 'cages,' in which the young were kept under as natural conditions as possible, while undergoing their metamorphosis. It is probably only a question of a few years before the Fish Com-