NUTRITION AND FEEDING MECHANISMS 231 



whalebone or baleen, which is a collective term for horny plates attached 

 to the roof of the mouth and hanging down into the buccal cavity. The 

 plates are arranged transversely to the long axis of the jaws and are very 

 numerous, over 300 having been counted in the right whales. On the inner 

 side the plates bear fine hair-like fringes which form an efficient filtering 

 apparatus. As the whale swims about at or near the surface, with mouth 

 open, planktonic organisms are strained off by the hair-like fringes of 

 whalebone and the water escapes through the sides of the mouth. When the 



Fig. 5.23. Head and Bill of the Broad-billed Prion Pachyptila forsteri 



(Left) a palatal view of the upper mandible, showing the baleen-like maxillary lamellae. 

 (Right) view of the head, showing the extensible pouch. (From Murphy (78).) 



lower jaw is raised and the tongue elevated, water is forced out of the mouth 

 cavity. The planktonic organisms which have been filtered off are left 

 stranded on the tongue and are swallowed. 



The principal food of whalebone whales consists of larger species of 

 plankton (krill). In the Antarctic, blue, fin and humpback whales (Balaenop- 

 tera and Megaptera) feed heavily and almost exclusively on the immense 

 shoals of Euphausia superba which abound there; this is in the summer 

 season. The majority of whales eat little in the winter, when they draw upon 

 their reserves of fat. These are supplemented by small quantities of Crusta- 

 cea and fish, captured in warmer waters of the Southern Hemisphere 

 during the winter months. The staple food of blue and fin whales (Balae- 

 nopterd) in the Northern Hemisphere is Meganyctiphanes norvegica during 

 the summer. During the winter, fin and humpback whales consume some 

 fish (clupeids (66)). 



MECHANISMS FOR DEALING WITH LARGE PARTICLES OR 



MASSES 



In this section are described methods for dealing with inactive food; 

 for seizing prey, and mechanisms for scraping and boring in connexion 

 with feeding. 



Ingestion of Inactive Food 



There are many benthic animals which swallow, with little selection, 

 sand, mud or other bottom deposits, from which they extract organic 



