NATURAL HISTORY OF AMERICAN LOBSTER, 217 



DISEASES AND FATALITIES OF THE LOBSTER. 



There are few specific diseases to which adult lobsters are subject so far as known, yet 

 they sometimes die off so rapidly as to lead one to suspect that they have fallen a prey 

 to infectious disease. 



Mr. N. F. Trefethen, of Portland, Me., relates the following experience: In May, 

 1893, he placed 100,000 lobsters in a pound at South Bristol, the area of which is about 

 3 acres. Very soon they began to die, and in a few days all of them were dead. 

 There was from 12 to 13 feet of water in this pound at flood tide and not less than 9 

 feet at low tide. The pound was probably very much overstocked, but it is difficult 

 to understand why these lobsters should have all died so suddenly, unless they were 

 either poisoned or attacked by disease. 



In the summer of 1889 a lobster with a large bunch on the side of the carapace was 

 captured in Vineyard Sound. On the top of this tumoid growth was a crater-like depres- 

 sion covered with a membrane. This was probably a sore resulting from a wound 

 which the animal had received in the back, and which failed to heal. A similar case is 

 mentioned by Rathbun. Further, according to Prince {218), Professor MTntosh has 

 described a tumor-like growth in a large lobster which originated in the wall of the 

 stomach sac, finally perforated the carapace and caused its death. 



In another place I have alluded to the experience of the U. S. Bureau of Fisheries 

 at Woods Hole in feeding the young lobsters with shredded menhaden. The larv ae 

 became infected with a fungus, which spread to all parts of their tissues and was soo n 

 fatal. 



To paraphrase the words of Hardy," the lobster, like many other aquatic animals, 

 is confronted by the same problem that has so long puzzled the shipbuilding world. 

 Larvae and spores are constantly settling upon the exposed surfaces of its body, where they 

 tend to deyelop growths which would interfere with their movements unless some 

 method of destroying or removing them were adopted. Hardy believes that "the 

 presence of a film of soluble slime on the surface of an animal immersed in water would, 

 like the copper sheathing of ships, mechanically prevent the occurrence of parasitic 

 growths by continually forming a fresh surface," and further that this slime may in 

 some cases have a specific poisonous power, directed chiefly against vegetable parasites. 



The lobster apparently secretes no slime, but its shell is studded with the openings 

 of the tegumental glands, the exact function and role of which is still in doubt. At all 

 events it will do no harm to raise the question whether these bodies may not help to 

 free the animal from such pests. That molting alone is not able to do this and that 

 some additional aid is often needed is amply proved by the great variety of messmates 

 or semiparasites which we have described. 



Ivobsters from a few inches in length up to the greatest size are sometimes driven 

 ashore and stranded on the beach, where, stunned or crushed by the force of the waves, 



"Hardy, W. B. The protective functions of the skin of certain animals. Journal of Physiology, vol. xm, no. 3 and 4. 

 London, 1894. 



