262 UNDERWATER GUIDE TO MARINE LIFE 



two interesting types of protective coloration, both of which create the illusion 

 that they are swimming backwards, thus forcing a predator to miss its mark. First, 

 the eye is camouflaged by a vertical line which runs through it. The eye is 

 the most difficult part of the body to hide since it is round, moving, and shiny. 

 Many animals, therefore, have evolved a line through it or a mark over it. The 

 raccoon, wood frog, and shrikes are familiar examples of this. The butterfly fishes 

 not only destroy the outline of the forward, true eye, but frequently add a false 

 eye to the rear in the form of a large, dark, usually ocellar, spot. A predator 

 aiming for this "head end" with its large "eye" is deceived and comes up with 

 nothing but a mouthful of water as the little fish scampers off unexpectedly in 

 a direction which looks backward. 



Butterfly fishes have pointed, extended snouts with the small mouth situated 

 at the end. With this snout they are able to poke about every nook and cranny 

 of reefs or rocks for their small invertebrate or plant food. They commonly eat 

 parasites attached to other species. Some large predators even allow them to 

 probe in their throats for parasites. The common East Coast species are three in 

 number. There are many similar Pacific species, mostly Polynesian. 



BANDED BUTTERFLY FISH: Chaetodofi striatiis—CoJor Plate 6 



Size: Up to 6 inches. 

 Distribution: West Indies to Florida. 



Identification: There is no rearward spot. The color is a very pale yellow or 

 white crossed with vertical black bands. 



COMMON BUTTERFLY FISH: Chaetodon ocellatns 



Size: Up to 8 inches. 



Distribution: West Indies to Florida. Straggles to Cape Cod. 



Identification: This is a yellow fish with a dark line through the eye and 

 usually with a dark nonocellar spot at the base of the soft dorsal fin, but this 

 may be missing or enlarged (in young fish) to form a vertical band. The shape 

 is like that of the four-eyed butterfly fish. 



FOUR-EYED BUTTERFLY FISH: ChaetodoH caj)istratus—Color Plate 6 

 and Color Photografh 



Size: Up to 6 inches. 



Distribution: West Indies to Florida. Straggles to Cape Cod. 



Identification: The large ocellated spot on the rear part of the body is unmis- 

 takable. The body is delicately yellow to white and covered with very fine rows 

 of spots. This is the most common West Indian species. 



ANGELFISHES: Genera Pomacanthus, Holocanthus and Angelichthys 



These large and exceedingly lovely fishes are constant sources of the aesthetic 

 inspiration which many divers seek under water. Their movements can only 

 be described as majestic and stately. As the diver approaches them, they will 

 at first face him, swim toward him a bit, then turn in an arc so as to present the 

 full beauty of the velvety sides and fins, lending themselves admirably to pho- 

 tography. These fish will occasionally do this over and over, coming at the diver 

 first from behind a coral, then from out of a hole. 



