48 TEXT-BOOK OF ZOOLOGY 



D. Relations to Man. 



Being an energetic destroyer of vermin, the badger should rather 

 be protected than pursued. The skin, which is strong and durable, is 

 used as a water-tight covering for trunks, etc. From the long, bristly 

 hairs brushes of different kinds are manufactured. In some places also 

 the flesh is eaten, and the fat melted down or used as fuel. 



The badger is met with in the whole of Europe and Northern Asia. 



3. The Otter (Lutra vulgaris). 



(Length about 2 feet 6 inches.) 

 A. Structure of Body and Aquatic Mode of Life. 



1. No warm-blooded animal can survive a continued exposure to 

 severe cold (see p. 11). Water being a better conductor of heat than air, 

 a considerable cooling of an animal body results if immersed in it for a 

 prolonged time. The otter, however, is able to pass a large portion of 

 its life in water, and even in winter pursues its prey in the water, 

 though the surface may be covered with ice. Let us now examine by 

 what means the creature is protected against a loss of heat which would be 

 destructive to its life. 



(a) The skin of the otter is always kept well greased, and thus never 

 becomes really wet (compare with ducks and geese). This is effected by 

 special fat glands in the skin. 



(b) The fur is thick, and the bristles packed tightly upon the fur or 

 under-hair. In this way small air-spaces are formed, which prevent the 

 access of water to the skin. (This may be illustrated by dipping a bit of 

 velvet in water and observing the result.) Air, however, is a bad con- 

 ductor of heat. 



2. Most land animals can progress for a short time in water by 

 swimming. The otter, however, is much more of an aquatic than a 

 land animal ; it even pursues its prey by swimming or diving (see 

 Section B.). Its body, therefore, must be specially adapted for continued 

 and rapid swimming and; for diving. 



(a) The air-spaces between the hairs of the fur diminish the specific 

 weight, air being specifically lighter than water. 



(b) Friction is diminished, owing to the body being constantly kept 

 well lubricated and slippery. 



(c) The small, broad, flat head, the short, thick neck, and the 

 slender, narrow body, form a wedge, as it were, which cuts through the 

 water with ease. The body being of snake-like shape (hence the name 



