A METHOD OF LOBSTER CULTURE. 223 
Mode of swimming.—The young lobsters swim by means of vibratory 
movements of their exopodite appendages, which stand out like blades from the 
thoracic legs, and the swimming is augmented by irregular jerky strokes of the 
very muscular ‘‘tail’’ or abdomen, which, in all the larval stages, is bent at a 
considerable angle to the cephalothorax. The swimming must be characterized 
as slow and weak when we have in mind-for comparison that of most young 
fishes. At any time during the three larval stages the fry can easily be picked 
out by means of a small scoop, or even with the hand. 
In general, too, the swimming seems to be aimless in direction, so that the 
fry are easily carried along by the slightest current. This statement, however, 
though generally true, requires qualification, for under the influence of special 
stimuli the movements often become directive. The larve respond to varying 
directions and intensities of light and, in experimental tests, to the direction of 
electrical currents. They avoid, in many cases, light-colored objects if near, 
and they are attracted by food to a rather slight degree. They will go only 
very short distances, however, after particles of food or living prey. During 
all the larval stages they exhibit practically no instinct of fear and, while they 
avoid light surfaces, they do not try to escape capture. The heliotropic and 
photopathic reactions and what may be described as the general aimlessness 
of movement are things to be reckoned with in developing a practical method 
of lobster culture. 
Food.—The natural food of the lobster must, of course, consist of pelagic 
organisms. In an examination by Dr. L. W. Williams of the stomach contents 
of larve in all three stages taken from the rearing bags at our station,” a large 
percentage were shown to have fed upon copepods and diatoms. The young 
lobsters, however, are not distinctly fastidious in this respect, and the nature 
of the stomach contents of the fry in their natural habitat would doubtless be 
found to vary according to the variety of available pelagic food. 
Moulting and the larval stages.—The instincts and behavior and the general 
appearance of the three successive larval stages are generally similar in respect to 
the features just referred to. The stages are, however, structurally well defined 
and readily recognized, there being for each a number of clearly diagnostic 
peculiarities. (See text figures p. 224 and 225.) Among the most obvious and 
easily recognizable are, for the first stage, the small size of the larve and the 
absence of swimmerets on the under side of the abdomen; for the second stage, 
the somewhat increased size, the presence of several pairs of swimmerets and 
the absence of ‘‘tail fins” or the lateral appendages of the penultimate segment; 
for the third stage, the presence of both swimmerets and “tail fins.’’ All stages 
have the exopodite swimming appendages and the corresponding pelagic habit; 
none has the functional chelez or “‘big claws” of the adult lobster. 
According to the observations made by Doctor Hadley at our station the 
average measurements of the three successive larval stages are 8, 9%, and 11 
@Station of the Rhode Island Commission of Fisheries at Wickford, R. I., on Narragansett Bay. 
