208 



ANIMAL BIOLOGY 



Whales, Porpoises, Dolphins. - - As the absurd mistake 

 is sometimes made of confusing whales with fish, the pupil 

 may compare them in the following respects : eggs, nour- 

 ishment of young, fins, skin, eyes, size, breathing, tem- 

 perature, skeleton (Figs. 209, 379, and 397). 



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FIG. 378. HARPOONING GREENLAND WHALE 

 "(see Fig. 351). 



Porpoises and dolphins, which are smaller species of 

 whales, live near the shore and eat fish. Explain the ex- 

 pression " blow like a porpoise." They do not exceed five 

 or eight feet in length, while the deep-sea whales are from 

 thirty to seventy-five feet in length, being by far the largest 

 animals in the world. The size of the elephant is limited 

 by the weight that the bones and muscles support and 

 move. The whale's size is not so limited. 



The whale bears one young (rarely twins) at a time. 

 The mother carefully attends the young for a long time. 

 The blubber, or thick layer of fat beneath the skin, serves 

 to retain heat and keep the body up to the usual tempera- 

 ture of mammals in spite of the cold water. It also serves, 

 along with the immense lungs, to give lightness to the body. 



