142 THE FOOD OF ANIMALS 



the strand, not a few are parasitic, and some have become 

 adapted to a terrestrial life. They include the Amphipods, 

 such as Sandhoppers and their allies, which are flattened from 

 side to side, and the Isopods, which are flattened from above 

 downwards. 



Amphipods.— A very common example is the Sandhopper 

 {Talitrus locusta) (see vol. i, p. 415), which haunts the shore 

 between tide-marks, and in summer may be seen in countless 

 thousands, springing several inches into the air so as to be 

 visible some way off^ and looking almost like a quivering dust- 

 cloud hanging over the surface of the sand. Like most members 

 of its group, the Sandhopper lives chiefly, if not entirely, upon 

 decomposing animal matter, and close examination with the 

 aid of a powerful lens shows it to be possessed of strong biting 

 mandibles, two pairs of maxillee (see Lobster, vol. i, p. 406), and 

 a single pair of foot-jaws turned forwards so as to form a sort of 

 lower lip. In northern latitudes Crustacea of related kind occur 

 in such vast numbers as to be able to speedily do away with 

 the stranded and putrefying carcasses of even such large Cetacea 

 as whales and the like. An abundant and typical example of 

 freshwater forms belonging to the same group is the Freshwater 

 Shrimp {Gammarus locusta), and it may be observed in passing 

 that the term "shrimp", popularly applied in the case of this 

 and many other forms, is somewhat misleading, for the true 

 shrimps, with their stalked eyes and firm shield covering the 

 head and thorax, belong to the totally distinct and higher group 

 of Decapods (see vol. i, p. 410). 



Climbing about among sea-weed and zoophytes, in the tide- 

 pools of the British and many other coasts, we can often find 

 the weird-looking Skeleton-Shrimp {Caprella) (see vol. i, p. 415), 

 typical of a subdivision of the Sandhopper group, and distinguished 

 by an extraordinarily attenuated body. The abdomen is here 

 reduced to a mere tubercle, and the thorax is correspondingly 

 well-developed, its third pair of limbs bearing large climbing- 

 claws, while at its hinder end are three pairs of legs. Jaws 

 and foot-jaws are present as in a sandhopper, and behind the 

 latter come the second thoracic limbs, specialized into seizing 

 organs. Caprella may often be seen holding firmly to a zoophyte 

 and waiting patiently for booty, the presence of which is made 

 known by its two well-developed pairs of slender feelers. The 



