FEEDING OF MARINE ANIMALS 209 



in the open mouth, the recurved teeth of which effectively 

 prevent it from escaping. Diving birds have even been 

 discovered within Anglers. Some of the deep-sea Anglers 

 have a highly developed luminous organ at the tip of the 

 tentacle which can perhaps flash on and off at will. Other 

 of the deep-water fish have huge mouths and an unlimited 

 capacity for food, their stomachs being capable of such 

 expansion that their owners can swallow animals larger 

 than themselves (Plate 76). 



The feeding organs of fishes naturally vary with the type 

 of food. The wrasse, which feed on Crustacea or molluscs, 

 are able to crush them to pieces in their mouths by means of 

 specially powerful teeth in the mouth and throat, but the 

 young of the grey mullet which feed on fine particles and 

 are reported to do considerable damage to the oyster 

 beds, owing to the fact that they swallow great numbers 

 of the free swimming " larvae," have no teeth, really 

 sucking in their food. The adults have only weak teeth 

 and browse on encrusting weeds and the small crustaceans 

 in them, the stomach forming a gizzard for the crushing up 

 of this food. The Pipe-fishes also have a complete lack of 

 teeth and indeed suffer from a kind of permanent lock- 

 jaw ; they live on minute Crustacea which they take in by 

 sucking action. The beautiful green or blue Kakatua 

 of coral islands has a hard beak with which it rasps the 

 surface of coral rocks for encrusting sea weed. It was 

 originally thought actually to feed on the corals themselves. 

 The Trigger-fishes have jaws and teeth of exceptional 

 strength, those of one species, Balistes capriscus, being 

 shown in Plate 79. 



The feeding of whales forms a strange paradox, the 

 largest of all feeding on plankton, straining it through the 

 frayed fringes of their whalebone plates, while the rather 

 smaller Sperm whales feed on giant deep-sea squid which 



