THE FISHES 177 



ored like the bottom sand colored or brown or black and 

 the under side is white. When the flounder is first hatched, 

 the eyes are on each side of the head, and the animal swims 

 upright in the water like other fishes. But it soon rests on 

 the bottom ; it turns to one side, and as the body is turned 

 over the lower eye begins to move over to the other side. 

 Finally, we may close the series with the anglers, in which 

 the first dorsal spine is transformed into a sort of fishing- 

 pole with a bait at the end, which may sometimes serve to 

 lure the little fishes, which are soon swallowed when once 

 in reach of the capacious mouth. 



168. Internal anatomy. A few fishes are vegetarians, but 

 the greater number are carnivorous. Some swallow large 

 quantities of sand of the sea-bottom and absorb from it the 

 small organisms living there. Others are provided with 

 beaks for nipping off corals and tube-dwelling worms. Huge 

 plate-like teeth enable others to crush mollusks, sea-urchins, 

 and crabs, and many are adapted for preying upon other 

 fishes. The latter are often able to escape, owing to the 

 presence of numerous spines, sometimes supplied with 

 poison-glands; or their colors are protective, and a vast 

 number of devices are present which enable them with 

 some degree of surety to escape their enemies and capture 

 food. 



Usually, without mastication, the food passes into the 

 digestive tract (Fig. 107), which in the main resembles that 

 of the squirrel, but varies considerably according to the 

 nature of the food it is required to absorb. As in other 

 animals, it is usually longer in the vegetable feeders. In 

 most fishes the walls of the canal are pushed out at the 

 junction of the stomach and intestine, to form numerous 

 processes like so many glove-fingers (the pyloric coeca, Fig. 

 107, py-c.), which probably serve to increase the absorptive 

 surface. The same result is obtained in other ways, chiefly 

 by numerous folds of the lining of the canal. 



The blood-system is much more complex in the fishes 



