THE AQUATIC VERTEBRATES lo6l 



codfishes have shown that their sense of smell gives them but 

 vague information, while the senses of touch and taste, whose organs 

 are found over the entire body, enable the catfish to detect and 

 secure any food coming in contact with any part of the body. In 

 contrast to the bhndfishes (Amblyopsis) of the Ohio Valley caves, 

 the Point Loma blindfish secures its food through touch and taste. 

 A hungry Point Loma blindfish with a stroke of the fins brings 

 the mouth in position for operations as soon as any portion of its 

 skin, especially of the head, comes in contact with food. 



Fish Enemies. — The enemies of fishes are the mink, otter, an 

 occasional raccoon and cat among the mammals; the kingfisher, 

 herons, ducks, loons, and terns among birds; an occasional bull- 

 frog and possibly Necturus among batrachians; several snakes, 

 and many fishes, spawn eaters, fry catchers, lampreys, and adult- 

 eating, predacious fishes. 



The otter as a fish enemy has been practically eliminated. 71ie 

 occasional fish caught by the mink and raccoon will form but a 

 small annual total. In fact, by the changes incident to advancing 

 civilization, all but the aquatic enemies of the fishes have been 

 reduced to a point where their depredations can have but little 

 selective value. 



Fishes evidently could avoid terns and kingfishers by living below 

 the few inches penetrated by these divers. But the advantages of 

 food near the surface evidently outweigh the danger of being 

 caught, as long as a sudden dive or a dart forward will enable the 

 fish to escape. 



Herons and ducks are avoided by selecting water too deep for 

 these enemies. Color and swiftness are probably other adapta- 

 tions to the same enemies. The darter sits with outspread pec- 

 torals on the bottom of a stream or lake within easy reach of a 

 heron. A sudden motion of the powerful pectorals and he sits as 

 composedly somewhere else. The dart-like motion which gives the 

 darter its name is an adaptation to secure food and avoid enemies. 

 Swiftness, inconspicuousness, or ability to enter retreats are the 

 means of defense against the loon and his ilk. Howe\or, none 

 of the devices are always efficient. 



The greatest enemy of fishes is the spawn stealer. At Lake 



