Chapter XI.— BEHAVIOR AND RATE OF GROWTH. 

 BEHAVIOR OF YOUNG LOBSTERS. 



Having considered the general habits of the lobster in its successive stages of 

 development, we shall now discuss their behavior in more detail. 



In the summer of 1894 I tried a number of simple experiments to test the effect 

 of light upon the movements of the larval lobster. Twenty-five thousand young in 

 the first stage were placed in the observation pool at the Fish Commission station, 

 Woods Hole, Mass., in order that their behavior might be watched. The sun was 

 intermittently obscured by clouds during the greater part of the forenoon. When set 

 free, the larvae soon swarmed in a large cluster *near the surface, where they remained 

 for a short time. Presently all of them went down to a distance of from i to 2 feet, 

 and some of them to the bottom to a distance of 3 feet more. A lot of small cunners 

 then appeared on the scene and snapped up the larvae right and left. Two hours later 

 the remnant were dispersed over the whole pool, a large number remaining close to 

 the surface. At i o'clock in the afternoon the surface on the lee side still swarmed 

 with larvae. Occasionally one could be seen to attack and drag another down. They 

 swam with their usual aimless activity, now rising and falling and changing their direc- 

 tion frequently. The majority of them had now become quite red. Later in the 

 afternoon nearly all of the little lobsters had disappeared, having been swept out by 

 the tide or destroyed by the cunners or other fish in the pool. 



Various boxes were then constructed to admit diffuse light from above or direct 

 light through one end, grid ,]|;\typp iri t ^e first stae^e were found to move toward the 

 source of the light, whatever its intensity. In similar experiments made at another 

 time this reaction, which then seemed characteristic, was reversed, "showing possibly 

 that under certain conditions the larvae are negatively heliotropic ." At this time the 

 subject of animal behavior had hardly emerged as a branch of experimental biology, 

 with its more exact analytical methods and criteria which have since been evolved. 



The experimental work of Bohn (27) on Homarus gamtnarus and of Hadley 

 (ijj) in particular on the American lobster have illustrated the importance of study- 

 ing the behavior of such an animal throughout the entire course of its development, 

 and at the same time have revealed the great variety and complexity of the problems 

 involved. The following paragraphs are little more than a summary and running 

 commentary on some of their results. 



For the analysis of certain problems in behavior the lobsters are unsurpassed, 

 since with the proper apparatus they may be hatched in unlimited numbers and main- 

 tained to any required age or stage during the summer months. The results of studies 

 thus far made show that while the crustacean larvae may respond promptly and in a 

 definite manner to a certain stimulus, their behavior is complex and essentially variable, 

 and that at any given point of time it is the result of all the influences at work. 



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