52 THE STORY OF LIFE IN THE SEAS. 



there are no such surfaces. The body of the 

 Fish is usually more rounded in form, and no 

 well-marked limit can be assigned to the coloured 

 upper surface and the pale silvery under side. 

 These Fish are in nearly all cases rapid and 

 powerful swimmers, rushing through the water 

 after their prey, or away from their enemies, by 

 vigorous lateral movements of their tails. 



A curious exception to this general rule among 

 the Fish occurs in the family of the Lump- 

 suckers. These Fish are found on the English, 

 but more commonly on the Scottish coast, and are 

 distinguished by the presence of a sucker, formed 

 by the throat fins, on the under side of the head. 

 By means of this the Lump-sucker is able to 

 attach itself so firmly to rocks and stones that it 

 can only with considerable difficulty be removed 

 from the object to which it is attached. 



Of the Fish that are commonly found among 

 the rocks, a very considerable number migrate 

 from time to time to other parts of the sea, and 

 may be caught in the trawl on sandy or shingly 

 bottom, or even in the drift nets at the surface of 

 the sea. A large number of Fish belonging to the 

 family of the Codfishes frequent the rocks during 

 a part of their lives. The Pollack is distinguished 

 from most of the others by the absence of a barbel 

 on the lower jaw, and is one of the persistent rock 

 frequenters. In the adult condition it feeds almost 

 entirely upon other Fish, although in the younger 

 stages of its life Crustaceans, Worms, and other 

 Invertebrates seem to form the bulk of its food. 



The true Cod and the Haddock seem to have a 

 much wider range, occurring on shingly bottoms, 



