324 Fish Stories 



grown. It is almost spherical in shape, is enveloped in a 

 hard, bony covering, and this again is protected by long 

 spines, so that it looks like an animated pin-cushion. 



It is a degenerate fish. By that we mean that it is fitted 

 for a narrower field of life than its ancestors. It is less 

 active, less competent, can do fewer things. It is at the 

 same time highly specialized; that is, fitted for very special 

 purposes. And these purposes are all of the nature of de- 

 fense against other fishes. Its cumbersome suit of mail 

 serves for defense only. Other fishes cannot crush it. Its 

 sharp spines protect it thoroughly. Other fishes cannot 

 swallow it. The very short tail and small fins are defensive. 

 Other fishes cannot bite them off. Even the small mouth 

 of the porcupine fish is made just as harmless to other fishes 

 as it could well be. Each jaw is like a parrot's beak or still 

 more like a turtle's, and all the teeth in each jaw are grown 

 together into one, and this one is blunt-edged, and very much 

 contracted. If you put your finger in it, the fish can give 

 you a good bite, but it cannot reach out after anything, nor 

 hold anything that tries to get away. Little crabs and snails 

 it can hold, and on these it feeds. 



Even the flesh of the porcupine fish, thin and dry as it 

 seems, is fitted up for its protection. Whatever may devour 

 a porcupine fish will never touch another. In its substance 

 are bitter alkaloids, something remotely Hke strychnine in 

 taste and in effect. They poison other fishes. They may 

 even poison man, if eaten in some quantity. The flesh of 

 the porcupine fish, as of numerous related species, causes 

 the disease in the tropics called ciguatera. This is often 

 fatal, and shows itself in severe nervous disturbances and 

 violent irritation of the alimentary canal. These poisonous, 

 bitter alkaloids are common in some kinds of fishes in the 

 tropics, but do not develop in cold waters. For this reason 

 ciguatera is a disease of the torrid zone only. 



The purpose of these alkaloids in the flesh is thought to 

 be the protection of the species. The individual eating is 



