BONY FISHES 28 1 



Another denizen of the muddy bottom is the Spiny Loach (Cobitis 

 teenia). Its elongated, eel-like body is accordingly also dark-coloured 

 (leather yellow to brown), and its mouth equipped with (six) barbels. 

 This fish, especially when living in water poor in oxygen, frequently 

 comes up to the surface in order to take in air with its mouth. The air 

 thus swallowed is deprived of its oxygen in the intestine (intestinal 

 respiration). 



The Groundling or Loach (C. barbatula) is very similar, but rather 

 larger ; it lives in clear, running waters. 



The Pike (Esox lucius). 



(Length up to about 3£ feet.) 



The pike is undoubtedly the most dreaded pirate of our waters, 

 swallowing every aquatic creature it can master, and not even sparing 

 its fellows of its own species. 



(a) When fully grown (weighing then sometimes over 30 pounds) its 

 size and strength are such as only few fishes (salmon and sheat-fish) 

 can resist. 



(b) During the day the pike may be seen in a motionless attitude 

 among water plants. In its retreat it is rendered inconspicuous by the 

 greenish colour of the back and sides of the body, the latter being 

 crossed by several dark transverse bands or spotted with black. 



(e) Swift as an arrow the fish darts upon its prey. (Why must the 

 pike be a rapid swimmer ? Compare it with predaceous members of other 

 classes of animals.) Its elongated body and sharply-pointed head enable 

 it to cut through the water with great speed. (Describe its fins.) 



{d) The mouth is shaped like a duck's bill, with a wide gape extending 

 up to the eyes, in which the victim is rapidly seized, and from which 

 escape is impossible, for the mouth of the monster literally bristles with 



(e) Teeth. — Some of the teeth are curved backwards (compare with 

 snakes). After being severely wounded by the larger two-edged fangs 

 which are scattered among the smaller so-called " hackle- teeth," and 

 which penetrate deeply into the flesh, the victim is liberated for a 

 moment, in order to be seized afresh and swallowed alive with the head 

 foremost. (Why ?) 



(f) The pharynx is wide, and the pharyngeal bones are armed with 

 teeth, while the oesophagus is very dilatable. 



(g) The intestine, as in all carnivores (see cat), is short and muscular. 

 (Compare the pike with the carp in regard to these various points.) 



(h) Importance to Man. — The flesh of the pike is much esteemed as 

 food. Naturally, the pike is kept carefully away from ponds which are 



