PISCES 



249 



themselves to sharks and other marine forms. The remoras have 

 been used by natives in capturing other fish (Gudger). The goose 

 fishy or angler {Lophiidae), is a fish with an enormous mouth and a 

 modified first dorsal ray which it uses as a lure. The common 

 mackerel^ the Spanish mackerel, and the tuna (called " horse- 

 mackerel ") are examples of the family Scombridae. The tuna is 

 large, sometimes weighing 150 lbs. 



Fig. 131. Head fish, Mola mola. (Courtesy of Amer. Mus. of Nat. Hist.) 



T\\efla fishes {Pleuronectidae) include the smaller species and the 

 large halibut {holibui). The lateral eye of one side moves over to 

 the other and the fish lies on its side. Flounders are well pigmented 

 and have been utilized in experiments by Sumner and Mast who 

 showed that color change will assume the character of the back- 

 ground-checkerboard, etc., if the eyes are intact. Blinded, the fish 

 cannot change color, to match its environment. (Figure 133.) 



The upper jaw of the swordfish {Xiphiidae) (Figure 134) is 

 extended into a formidable weapon. Instances are recorded in 

 which a large swordfish (500 lbs.) has penetrated the bottom of a 



