84 ANIMAL LIFE 



titbit of the herring, in pursuit of which these 

 migratory fish travel in bands from sea to sea 

 with an avidity that is never surfeited. In like 

 manner, though with the help of a vast baleen sieve, 

 the right-whales thin out the stream of minute animal 

 life that sets from the Arctic to the temperate zone. 

 Should the sea fail, as it does in winter, to break out 

 into this dance of drifting life, the active swimmers 

 retire to the bottom or deeper water, where they 

 discover an abundance of food in the vegetarian 

 Crustacea and molluscs, in the oily eggs of the herring 

 and the newly hatched fry of the plaice and cod. Let 

 but a shrimp stir a tentacle and the hungry dab seizes 

 him. The John Dory stalks the swimming shrimp, 

 going forward with his flat body edgewise and unseen, 

 and at last lunging out with his sucking, extensible 

 jaws. The dogfish, no longer sustained by nourishing 

 herring, bolts crabs and whelks to satisfy his raging 

 hunger. 



Marine invertebrate life teaches the same con- 

 clusion. Cuttlefish, masters of marine invertebrates, 

 are the most active swimmers it produces, and 

 dart in vast shoals through the water, first in one 

 direction, and then in a tangential track, forwards 

 and backwards with equal facility. In shape and 

 movement they resemble fish. To supply the de- 

 mands for such energy the scanty algae of the mid- 

 ocean are inadequate and a richer diet is requisite. 

 This the squid, as they are called, find in the herring 

 and mackerel. They follow the migratory shoals 



