336 BULLETIN OF THE BUREAU OF FISHERIES. 



water must be gently agitated so that larvae will not settle and become smothered in a 

 mass of decomposing food and sediment at the bottom. 



The natural food of the larval lobster consists of minute pelagic organisms, whether 

 animals or plants, which through their own movements or their lightness remain sus- 

 pended near the surface, such as diatoms and other protophytes, copepods, the larvae 

 of crustaceans, echinoderms, worms, and mollusks, the floating eggs of fishes, and, in fact, 

 any member of the pelagic fauna which comes into their zone and is not too large for 

 them to master. 



The young lobster does not show, however, a very precise discrimination in its food. 

 It will snap up almost any moving object, living or dead, which it is able to seize and 

 swallow. Thus I have found in the stomachs of the older larvae vegetable fibers, the 

 scale of a moth or butterfly, and fine granules of sand. 



An examination of the stomachs of a number of larvae which were reared in aquaria 

 to the fourth and fifth stages, when they measured 1 3 to 1 4 millimeters in length, revealed 

 the following substances: (i) Diatoms in abundance, chiefly Navicula and the long 

 tangled ribbons of Tabellaria; (2) remains of Crustacea, probably parts of young lobsters; 

 (3) bacteria in great numbers; (4) cotton and linen fibers and parts of algae; (5) amor- 

 phous matter, with sand grains. The sediment of the jar contained the same species 

 of diatoms in abundance, and amorphous debris similar to that found in the stomach 

 and intestine. 



Analysis of the stomach contents of a lobsterling captured in Vineyard Sound August 

 12 (length, 15 mm.) gave the following organisms : (i) Parts of crustaceans; (2) diatoms; 

 (3) shreds of algs. In another young lobster taken at the same time (length 17 mm.) 

 there were (i) parts of crustaceans, (2) large numbers of diatoms, (3) filaments of green 

 algae and thin sheets or shreds of vegetable tissue, (4) the scale of a lepidopterous insect, 

 (5) bacteria, and (6) amorphous matter in large masses. The diatoms and small amor- 

 phous particles of every kind may be regarded as partly or wholly incidental — that is, 

 taken in with more important food material. 



Williams (279) carefully examined the stomachs of one hundred larval and fourth- 

 stage lobsters, which were being reared in the hatching bags at the Wickford (R. I.) 

 station, and were fed with finely chopped clams. Thirty-seven contained copepods to 

 the amount of 37 per cent of the total quantity of food present, and these favorite 

 crustaceanswere especially abundant in the stomachs of the second and third stage larvae. 

 Larval lobsters were almost invariably absent from their menu, from which he con- 

 cludes "that a lobster in the presence of abundant food will not attack his kind." 



A further discussion of food for artificially reared lobsters is given at the close of this 

 chapter. 



The length of the stage periods and the size attained by the lobster in each are 

 subject to variations to be considered later: I^ength of first larva, 7.50 to 8.03 millimeters, 

 average 7.84 millimeters (of 15 individuals); stage period, i to 5 days (Woods Hole, 

 Mass.); length, 8.2 millimeters; period, 2 to 3 days, which may be extended to 25 days 

 with the temperature at 60° F. (Mead* and Hadley for Wickford, R. I.) 



