THE LOBSTER FISHERY 635 



and antennulae) . Four of the 6 tail joints bear spines, 2 on each side, and 1 stand- 

 ing erect in the middle. The yellow liver is plainly visible through the translucent 

 shell. The third pair of foot-jaws and 5 pairs of legs bear paddle-like outer branches, 

 by the rapid movement of which the larval lobster swims about at a moderate 

 speed. During this stage the head is commonly directed downward and the body 

 usually bent in quadrant form. The direction is aimless unless influenced by light 

 and food and the like. At this stage the larva is about Yz of an inch in length from 

 the tip of the snout to the end of the tail. 



During the first 2 weeks of its existence the larval lobster moults 3 times, chang- 

 ing slightly in appearance after each moult. The life of this crustacean is made 

 up of a series of stages, each of which represents the time passed between succes- 

 sive castings of the shell. During the first 4 periods the growth is most rapid and 

 changes most pronounced. After the sixth or seventh moult there is little appar- 

 ent change, except for increase in size. Herrick (1909) described the changes in 

 the larval state of the lobster in great detail; a brief outline of his description 

 follows : 



Toward the end of the second week the green color begins to be observed 

 along the back of the young lobster. The paired swimmerets can be seen along 

 the underside of the tail, and the snout becomes toothed. At this stage the larva 

 is approximately M inch long. 



The large claws begin to develop during the third week, with the toothlike 

 projections along the inside becoming visible. The eye does not show any appre- 

 ciable change at this time, but the green coloration can be observed as spots in 

 the thin shell. 



The resemblance to the adult lobster becomes more noticeable during the 

 fourth week. The color is appreciably more pronounced and the length has in- 

 creased to something more than /2 inch. The color has deepened to a reddish 

 brown and the erect spines down the back have disappeared. 



It is during the period from 6 weeks to 2 months that the young lobster com- 

 pletely loses the translucency which has been characteristic of it so far. It is still 

 an active surface swimmer, but its new reddish brown tint makes it harder to 

 distinguish from the larva of many other species, such as the young cod or sculpin, 

 which live in the surface water. 



After 1 or 2 weeks more, when it is about % of an inch long, it migrates toward 

 the shore. The color has become definitely darker and may range from dark green 

 to pale blue or greenish brown. Its actions indicate that it will soon seek the bottom 

 mud, where it will remain throughout the remainder of its life if left undisturbed. 



When it is about 3 months old, the external characters of sex begin to develop, 

 and it is possible to differentiate between the male and the female. It has now 

 passed from an almost transparent mite swimming in the open sea to a heavy 

 opaque bottom-living scavenger. The eyes have become quite prominent. It 

 feeds on minute marine plants, other crustaceans, and in fact anything that comes 

 within reach and is not too large for it to handle. During the first year of its life 

 it will molt from 14 to 17 times and will gain as much as 20 per cent in bulk at 

 each molt. It is estimated that a lobster measuring lOM inches in length has molted 

 about 25 or 26 times, and its age is about 5 years. A female this size will pro- 

 duce about 10,000 eggs each time she spawns. 



