Habits and Adaptations 255 



Many fish, like the flounder, seek protection in imitating 

 their background, but there are others which protect them- 

 selves by passing most of their lives in unlikely or inaccessible 

 places. One tiny inhabitant of Brazilian fresh waters actually 

 lives inside other fishes. It is so small that it can slip into the 

 chamber which houses the gills, presumably doing this when 

 the gill cover is open to let the water escape, and in this 

 extraordinary spot it makes its home. The natives call it the 

 candtruy and are in great dread of it when they go into the 

 water, for it has been known to enter the excretory orifices of 

 human beings, from which it cannot be extracted on account 

 of its sharp, backwardly pointing spines. 



It may be assumed that this is an error on the part of the 

 fish. Entry into the organ is supposed to occur during urina- 

 tion by the human under water, when the outgoing stream 

 presumably resembles, to the candiru, the expiratory current 

 from the gill chamber of a fish. Certainly no fish would de- 

 liberately enter a hole from which there was no way of 

 emerging, and to be stuck in the human urethra must be 

 most unpleasant for the candiru, but it is even more unpleas- 

 ant for the human, and the only way to prevent the intruder 

 from reaching the bladder and causing death is to perform 

 an immediate operation. 



There is one fish which has even odder ideas about the way 

 to protect itself from its enemies. The candiru by mistake 

 sometimes lands in strange places, but this creature, which 

 rejoices in the operatic name of Fierasjer^ deliberately 

 chooses them. 



Fierasfer lives in tropical shallows. In the same waters 

 there lives a member of the starfish group called a holo- 

 thurian. It has so altered its shape that it looks like nothing 

 more nor less than a gigantic and rather dirty cucumber. In 



^ Ichthyologists have recently changed this to the unromantic sounding 

 Carafus. 



