HABITS AND DEVELOPMENT OF THE LOBSTER. 77 



ster while confined in an aquarium to catcli and devour the sea-robin. Lobsters feed 

 chiefly by night, when they are far more active than in the day. They are quite 

 sensitive to strong sunlight, and are often found in the daytime under stones or 

 bunches of seaweed, or lying at the mouths of their burrows. The lobster not only 

 digs up the bottom in its search tor shellfish and covers itself with mud in cold 

 weather, but burrows, under some conditions at least, as extensively as the muskrat 

 or prairie dog. This is certainly true of lobsters kept in pounds, where the mud banks 

 are sometimes so extensively tunneled by them from below as to afford but insecure 

 footing to a man. They dig horizontally into the bank to a distance of from 3 to 

 5 feet, and during the day may be seen lying in their burrows with their long sensi- 

 tive " feelers,'' or antennae, outstretched, ready to warn them of the approach of an 

 enemy, and with their large claws ready to strike a blow should the opportunity arise. 

 If the hole is exposed at low tide they will leave it in summer, but are not so careful 

 to do this in winter, when they are far less active. 



Next to reproducing its kind, the act of molting is the most important in the life 

 of this animal. The whole body is covered by a chitinous shell, in which salts of 

 lime are deposited, giving to parts of it the hardness of stone. When once formed 

 the shell admits of no increase in size, since it is a dead structure, excreted by the 

 skin below it, and when it is outgrown it must be cast off and replaced by a new and 

 larger shell. The new shell is gradually excreted under the old one, and when the 

 latter is discarded the new shell is soft and flexible, and is easily distended to meet 

 the requirements of growth. The growth of the lobster, and of every arthropod, thus 

 takes place, from infancy to old age, by a series of stages, characterized by the shed- 

 ding of the outgrown old shell, a sudden increase in size, and the gradual hardening 

 of the shell newly formed. Not only is the external skeleton cast off in the molt and 

 the linings of the masticatory stomach, the (esophagus and intestine, but also the 

 internal skeleton, which consists for the most part of a complicated linkwork of hard 

 tendons. This is rendered possible from the fact that all these structures are derived 

 from infolded portions of the skin, and in molting they are simply drawn out of their 

 original folds or pockets. It is thus easy to see why the molting period is a critical one. 



It requires from two to three weeks to form a tolerably hard shell, and from two 

 to three months to produce one which is quite as hard as that cast off. Since the 

 process of molting involves a long series of changes it is not surprising that a number 

 of names have been applied to lobsters while undergoing them. The terms ''black 

 shell," "crack back," or "shedder" are used to designate a lobster which is nearly 

 ready to molt. "Soft shell, " "buckle shell," or "paper shell " apply to one which has 

 recently shed, the shell being easily compressed by the fingers. A "hard shell' 1 or 

 "old shell" lobster is one in which the shell has attained, or nearly attained, its maxi- 

 mum weight and strength. 



In the final act of molting, which lasted in one case which 1 witnessed exactly five 

 minutes, the lobster lies on its side, and bending its body, distends the membrane 

 between the "tail" and the shell of the back. This membrane finally bursts, and the 

 front part of the body, the large claws, and other appendages are gradually with- 

 drawn from their old armor, the "tail" coming out last. To aid this process, the lime 

 salts have been absorbed from some of the joints of the legs which carry the large 

 claws, so that the investing shell can be distended to an unusual size, and absorption 

 also takes place along the median line of the back. Notwithstanding this, the tissues 



