FEEDING 



283 



^:^=^ 



Figure 163. Diagrammatic sketch of the course of the layer of cutaneous muscles between the 

 two lower jaws {right) and of the muscles between the lower jaws and the hyoid bone {left) in a 



Rorqual. 



cutaneous muscles which run diagonally from the centre of the lo\ver jaw 

 to either side of its edges. These muscles consist of different layers running 

 in alternating directions (Fig. 163). The contraction of the bottom of the 

 mouth is greatly aided by the presence of large quantities of elastic fibre 

 in its connective tissue (Sokolov, 1958). 



In addition, longitudinal geniohyoid and mylohyoid muscles run from 

 the jaws to the hyoid bone of the tongue. All these muscles are^ of course, 

 used for reducing the size of the mouth once the prey has been seized, and 

 for squeezing out the water between the whalebones (Fig. 164). The 

 tongue, too, is important in this process, since it may be said to be part and 

 parcel of the bottom of the mouth. 



Whales do, in fact, lack our own freely movable tongue. Odontocete 

 tongues still have a short free tip, and so have those of Mysticete foetuses 

 (Fig. 165), in which, soon after birth, the base grows wider as it growls 

 longer, till finally the tongue is nothing but a massive swelling covering 

 practically the entire bottom of the mouth. The reader will best appreciate 

 how massive it really is if he is told that the tongue of a Blue Whale has 

 the same weight as an adult elephant, i.e. roughly four tons, or 2 -5 per cent 

 of the whale's total body-weight - a percentage which is vastly greater 

 than, for instance, in the case of man. Unfortimately for us. Rorqual 

 tongues are not very muscular and are therefore not edible. This is only 

 to be expected of so immovable an organ, which is in fact almost entirely 

 made up of spongy connective tissue. The tongue of Right Whales contains 

 much more muscular tissue than that of Rorquals. This tissue quickly 



