SALT-WATER FISHES 



CHAPTER I 



GENERAL FACTS ABOUT SEA FISH 



Fishes may, for present purposes, be described as cold-blooded, 

 backboned animals that live in water, breathing by gills which 

 are retained through life and attached to arches of bone or 

 cartilage. The limbs are known as fins. The outer covering 

 of the body consists, in the majority of cases, of scales, but 

 these may be absent, or replaced by bony plates or rough 

 tubercles. 



Such is a very brief definition of the members of 

 the class. It must, even to the most superficial observer, 

 be obvious that the fishes of our seas, rather less than two 

 hundred in number, have some characters in common. They 

 all have a backbone, or skeleton, of either bone or gristle. In 

 this they resemble ourselves. They differ from us, however, 

 in that they reside in water, have cold blood, and oxygenate 

 that blood by bringing it in contact at the gills with continual 

 currents of sea-water holding atmospheric air in suspension. 

 Frogs come in this respect between us and the fishes, for they 

 breathe with gills when young and with lungs when full grown. 

 Scales are a distinctive character of the majority of fishes, but 

 reptiles also have scales, of somewhat different formation. 

 Some fishes, on the other hand, have no scales, while in others 

 they are minute and all but buried in the skin. Nor can fishes 



I 



