FOOD /tND AIR TURNED INTO FLESH AND ENERGY 87 



In the case of carnivorous animals where prey is to be 

 captured, the same adaptations must exist, being neces- 

 sarily even more complex than those demanded for the 

 securing of vegetable food. Some of the special adap- 

 tations of animals for food-getting are described in 

 Chapter XVII. 



But food once obtained and ready to be eaten appears 

 under very many forms and there is accordingly great 

 variety of structure among the parts employed in eating. 

 Amoeba eats without a mouth. It extends any part of 

 its soft body over the little plant or animal it feeds upon. 

 In many Protozoa, however, there is a definite mouth- 

 place, as in Paramoecium, where the food particles are 

 gathered together in a little ball by the cilia, and then 

 pushed through the body-wall. The body of the fresh- 

 water hydra (see Chapter IX), incloses a digestive cavity, 

 the mouth being but an opening to this. In the higher 

 animals we find mouths arranged for cutting, filing, 

 sucking, crushing, gnawing, grinding, chiseling, pierc- 

 ing, sawing; in fact almost every device one could 

 think of for working in wood, bone, shell, flesh, liquid, 

 soft and hard material of many forms. 



The study of the mouth parts of animals belonging to 

 one group shows how the same parts may take on such 

 different forms as to make very different kinds of appa- 

 ratus. For example among the insects, the bee (fig. 50), 

 mosquito (fig. 51), tiger-beetle, dragon-fly (fig. 52), 

 moth (fig. 53), and squash-bug, while exhibiting great 

 variety of mouth parts show each the same pieces, but in 

 each so changed in form as to make up a combination pe- 

 culiar to it. Among birds there is not so great a range of 

 difference; still, the various beaks and bills of chickens, 

 cranes, sparrows, ducks, curlews, hawks, cross-bills, 

 puffins, and horn-bills illustrate how one form may be 

 adapted to many operations. Birds do not use the mouth 



