

Parasites and Predators 



passing fish come in contact with this thread the little 

 mussel has found what it was seeking. The sticky thread 

 adheres to the fish and the mussel as likely as not will come 

 in contact with the body of its new-found host Directly 

 this happens the shell-fish adheres with the tenacity of 

 a bull-dog ; it is enabled to do so because its valves are 

 armed with sharp hooks. Holding tight to the flesh of 

 the fish, considerable irritation is set up, and this causes 

 a cyst, a sort of case, to be formed around the mussel. 



Thus ensconced within the flesh of its host, the bivalve 

 continues its development, assumes the valves of the adult 

 in miniature and is ready to fend for itself. By this time 

 the cyst on its host's body withers and falls off, with the 

 result that the young mussel is set free. 



The subject of parasitology is one of the most absorb- 

 ingly interesting branches of natural history, but it is 

 hardly a subject that can be discussed in any work of 

 a popular nature. 



Among predators there are many animals of peculiar 

 habits. It is difficult to define a predator ; practically 

 every flesh-eating animal is a predator, for, of necessity, all 

 such creatures must hunt their prey. Of all these animals 

 the most interesting are those who allow their fellows to 

 do the hunting and then rob them of their hard-won spoils. 



The naturalist - Audubon instances an extraordinary 

 case of impudence which he observed in the southern 

 states of America. At a spot where brown pelicans were 

 common, black-headed gulls, in quantity, would lie in 

 wait for the larger birds. A pelican, fortunate enough to 

 have had a good catch, was the object of attention on the 

 part of the gulls. As the pelican swam shorewards, his 

 pouch well stocked with fish, the gulls harried him to such 

 an extent, even to alighting on his head, that he opened 

 his beak and out dropped some of his catch. The fish, as 

 they tumbled back into the water, were seized by the gulls, 

 who thus secured a meal without the trouble of hunting 

 for it. 



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