MOUTHS AND JAWS iii 



are highly sensitive, assisting in the search for food, and may- 

 be provided with special folds or ridges, or with numerous tiny 

 papillae abundantly supplied with small nerves. 



In the Weever-fishes (Trachinus) and Star-gazers (Urano- 

 scopus) the lower jaw is longer than the upper and directed 

 obliquely or even vertically upwards, so that the opening of 

 the mouth is more or less on the upper surface of the head. 

 The Weevers are fairly active fishes, but spend a good deal of 

 time buried in the sand with only the head exposed, from 

 which position they are able to pounce on the small fishes and 

 crustaceans forming their normal food (Fig. 58A). It has been 

 suggested that the brilliantly lustrous and mobile eyes of this 

 fish serve to lure the intended meal within reach of its jaws, 

 it being well known that fishes are attracted by shining or 

 highly coloured objects. The Star-gazer (Fig. 47E) is a less 

 active fish, with a stout, clumsy body and a box-shaped head, 

 flat on its upper surface and bounded in front by the vertical 

 lower jaw. It lacks the ability to chase and seize the small 

 fishes on which it feeds, and, therefore, resorts to cunning to 

 obtain a meal. A Mediterranean species is in the habit of 

 burying itself deeply, until only the small, mobile eyes are pro- 

 jecting, and the upper part of the mouth-opening appears as 

 a cleft in the sand. When thus hidden and immovable, the Star- 

 gazer is diflficult to see, having the general appearance of a 

 brownish grey stone almost concealed by sand, its presence 

 being betrayed only by the slight movements connected with 

 respiration. At times it protrudes from its mouth a little red 

 filament, which represents a membranous process of the valve 

 of the lower jaw. This is made to move about on the sand, 

 crawling, wriggling, contracting and expanding — in short, 

 imitating to perfection the movements of a small worm. There 

 can be little doubt that this serves as a bait to lure small fry 

 within reach of the concealed jaws of the Star-gazer, and the 

 deception is facilitated by the soft, dusky light of the shallow 

 waters in which it usually operates. Another species from the 

 coast of West Africa uses a broad membranous flap, gleaming 

 white in colour, for the same purpose. 



In most predaceous fishes with large mouths the bony jaws 

 are strong structures, but in many deep-sea forms, and par- 

 ticularly among the members of the suborder known as "Wide- 

 mouths" {Stomiatoidea) , they are relatively feeble and even 

 somewhat flexible (Fig. 91), although armed with a fearsome 

 array of large, pointed teeth. These fishes prey mainly on their 



