CH. II CHARACTERISTICS OF VALUABLE MARINE FISHES 33 



Star-fishes, jelly-fishes, oysters, lobsters, and many other 

 creatures belong to the great tribes of lower animals which have 

 no back-bone. Back-boned animals never have more than two 

 pairs of limbs, corresponding to our arms and legs, while the 

 lower animals, as for instance insects, crabs, and lobsters, may 

 have a great number of legs. 



Back-boned animals are better known to most people than 

 the lower animals. In fact with the exception of a few like the 

 oyster and lobster, which are eaten as delicacies, the lower 

 animals are usually regarded with more or less disgust. But 

 we all know enough about the back-boned animals to distinguish 

 between beasts, birds, reptiles, and fishes. We know that beasts 

 have hair, birds have feathers and wings, reptiles and fishes are 

 usually covered with scales. The scales of a reptile however are 

 fixed, and do not come off easily like those of fishes. But the 

 most important peculiarity of fishes is that they have gills which 

 are placed at the sides of slits or openings behind the head, 

 through which water passes from the throat to the outside of the 

 body. Now a whale or a porpoise, although its body is shaped 

 much like that of a fish, has no gills and no scales. These 

 creatures are therefore not fishes, not of the same class of animals 

 as mackerel, herring, or shark. What then are they ^ Ex- 

 amination shows that they have some traces of hair on their 

 skins. They also breathe air by means of lungs just as we do. 

 Every one knows that a whale spouts or blows, which means 

 that it comes up to the surface of the water to breathe out the 

 air in its chest, and takes in a fresh breath before it dives again. 

 But this is not all. The whale and porpoise and other such 

 creatures bring forth their young alive and suckle them after- 

 wards, exactly in the same way as dogs or cats or other quad- 

 rupeds. They belong therefore to the tribe of beasts, although 

 they live entirely in the sea, and never, as seals do, emerge on 

 to the shore. They are beasts which have left their kindred and 

 taken to a sea-faring life. 



The lower animals which inhabit the sea form five very 

 distinct great tribes, differing from one another in structure of 

 body and mode of life, as much as they differ from fishes. 

 The following well-known animals are representative examples 

 of these tribes : lobster, oyster, lug-worm, star-fish, and jelly- 

 fish. The lobster belongs to the tribe of Crustacea, sufficiently 



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