176 



THE INTERNAL ENVIRONMENT OF THE BODY 



Part III 



Pinch and snap-back 

 Dragonfly nympn 



Incoming current 

 Rotifer 



Soft lip and suction 

 Earthworm 



Saw-edged tongue 

 Woodpecker 



Long distance suction 

 Butterfly 



Fig. 11.5. Animals gather food into their mouths by many devices. Circlets of 

 cilia create currents of water on which particles ride toward the mouth; earthworm, 

 a soft lip and ring of muscle grip the leaf and the suction of the pharynx pulls 

 it in; dragonfly nymph with underlip outstretched to grasp its prey; woodpecker 

 hammers its bill into the wood and saws with its tongue; butterfly extends its 

 proboscis to the nectar of the flower and sucks. 



elaborate filters. Other animals grasp food within a ring of muscle located in 

 their fleshy lips, sucking it in as earthworms grip a wisp of leaves, and as in- 

 fant mammals suck milk from a nipple. Most of the vertebrates seize their food 

 with the aid of a beak or various kinds of teeth. Dogs lunge forward, clutch 

 meat with their teeth, and hold it against the ridges on the hard palate. 



With each lap of its tongue a cat gathers up milk and throws it well back 

 into the gateway of its throat or, with strong strokes of its tongue, rasps the 

 flesh from a bone. With strokes like these but rougher and stronger lions clean 

 up the carcass of a zebra. A giraffe wraps its tongue around high-hanging 

 leaves and pulls them down to its grasp; a cow does the same with a bunch of 

 hay from the hayrack. Woodpeckers hunt over the bark of trees using their 

 tongues like bayonets to pierce the grubs (Fig. 11.5). Thus, by thousands of 



