INXAND FISHERIES. 05 



lodg-ment on tlie youiii^' lobster. Diatoms, fiiu.q'i, and eveu g-reen 

 alg-ffi, t>Tow upon tlieni, and often to such an extent as to cause 

 the destruction of the host. When the skin is shed, as the 

 h^bster goes from one stag-e to the next, the whole collection of 

 parasites is shed with the cast-off skin, and the lobster is again 

 clean. The more frequently the skin is cast, the less danger there 

 is from the accumulation of parasites. 



3. What are the general hahitt< of life in the first four stages ? — 

 Some of the habits of the young are described in other chapters, 

 but these observations, with certain additional ones, may be 

 brought together here for convenience. 



Swimming. — From the time they are hatched until they reach 

 the fourth stage they are essentially swimming animals, and are 

 in no way adapted for living on the bottou or in contact with any 

 solid substance. They are constantly in motion ; in moments of 

 apparent rest the motion of the swimmerets prevents them from 

 sinking, and for the greater part of the time they are swimming 

 around or executing absurd jerking movements by sudden strokes 

 of the tail. Only slightly do they direct their movements toward 

 particular objects or places, and they are carried b}^ the current 

 in the direction of least resistance. Their constant aimless activity 

 tends to keep them suspended in the water and occasionally l)rings 

 them into contact Avitli food, but does not protect them from 

 their enemies ; indeed, as they have no sense of fear and are very 

 conspicuous in the Avater, they fall prey to all sorts of animals^ 

 fishes, large and small, shrimji, and eveu to their own brethren. 



They swim sometimes at the surface of the water, but again 

 show a tendency to sink to lower depths. The causes of the alter- 

 nate rising and sinking of these larvje and of other swimming 

 animals like the jelly-fish, young star-fish, etc., are still obscure. 

 Recent researches have demonstrated for certain species that the 

 direction and intensity of light and the variations in the tempera- 

 ture are among the immediate causes. Undoubtedly the move- 

 ments of the loV)ster-frv are affected by the light and perhaps also 



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