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COLLEGE ZOOLOGY 



Figure 263. An ancient fish [Latimeria), first caught off the coast of Africa in 1938; sup- 

 posedly extinct for milhons of years. It is a "Hving fossil/' estimated to have lived in the 

 Devonian period. Length about 5 feet. Note the thick lobe-shaped fins. (Courtesy of Sport and 

 General Press Agency, Ltd., London.) 



two species of paddlefishes are now known: 

 Polyodon lives in the Mississippi Valley, and 

 Psephurus in China. The fresh-water dogfish, 

 Amia calva, is the only existing species of 

 the family Amiidae. 



Fishes that live in caves 



Six species of cave fishes hve in the subter- 

 ranean streams of the cave region of In- 

 diana, Kentucky, and Missouri. They are 

 small, but of special interest because the 

 eyes of some are rudimentary and covered 

 with a thick skin. Cavefish [Amblyopsis) 

 (Fig. 252) is common in the River Styx of 

 Mammoth Cave. Did the sightless cave 

 dwellers lose their eyes after they took up 

 cave life, or were they blind fishes before 

 they began their life underground? The an- 

 swer is, we do not know. 



Flying fish 



Sixty-five or more species of flying fish live 

 in warm seas (Fig. 252). Some are able to 

 leave the water and, rising in the air a few 

 yards, "fly" a distance of from a few rods to 

 more than Vs mile. Contrary to a popular 

 belief, the pectoral fins do not force the fish 



forward, but simply sustain the body in the 

 air. It is the tail fin only that is used for 

 fonvard propulsion when the fish skims the 

 water surface during the "take-off." 



Eels 



The true eels (Fig. 252) should not be 

 confused with the so-called lamprey eels 

 which are cyclostomes. The single species of 

 North American fresh-water eel, Anguilld 

 rostrata occurs in the streams of the Atlantic 

 Coast. It is long and slender, and its scales 

 are inconspicuous. The dorsal, caudal, and 

 anal fins are continuous. Eels enter the sea 

 in the autumn to spawn, after which they 

 die. The eggs are laid in deep water off the 

 Bermuda shore. The young develop in the 

 sea and then migrate up the rivers. 



Sticklebacks 



The famous nest-building stickleback 

 (Fig. 266), has 5 large spines on its back. 

 The nest is built of sticks fastened together 

 with threads secreted by a gland in the male. 

 The female lays eggs in the nest; the male 

 then enters the nest and fertilizes them, after 

 which he guards them from intruders. 



