THE AQUATIC VERTEBRATES 1057 



prey and deliberately pick it from the water. Such are provided 

 with teeth either in their mouths or in their gullets. Another 

 series probably including the spoonbill catfish take in large quanti- 

 ties of water and strain the plankton from it. They have weak 

 teeth or none and specially-adapted gill rakers for straining the 

 water. 



The various darters, a peculiar American product, are all lit- 

 toral. They rest on their pectorals on the bottom in shallow 

 water. With head erect and eyes protruding they are ready for 

 anything that moves within their range of vision. They are found 

 among weeds and gravel, chiefly in flowing water so shallow that 



FIG. 1547. Johnny Darter, Boleosoma nigrum Rafinesque. Actual size, 55 mm. long. 



the surface is rippled. Associated with them, or in places similar 

 to these, in favorable localities, are miller's-thumbs. The pirate 

 perch and trout perch should probably also be placed here. 



Other bottom fishes with sucker mouth and elongate alimentary 

 canal are found over mud bottoms. These include Campostoma, 

 suckers, carp, and sturgeon in North America. In tropical America 

 their place is taken by peculiar armored relatives of the catfishes, 

 the Loricariidae. Lastly, the large, predacious fishes treat the 

 smaller fishes as they in their turn treat the plankton. Here be- 

 long the muscalonge, the pickerels, salmon trout, and the basses. 

 Our nocturnal catfishes and the ubiquitous eel are omnivorous. 

 They take what they can. Everything that tastes or moves and 

 is within reach is food for the nocturnal catfish. Some blindfishes 

 planted in a pool had a way of disappearing that was mysterious, 

 until the pool was drained and the sardonic catfish, lurking under a 

 rock and found in possession of the last blindfish partly digested, 

 solved the mystery. 



Fishes are adapted to their food in structure as well as habit. 



