40 UNDERWATER GUIDE TO MARINE LIFE 



brain. Third, and most significant, the brain interprets that picture. The eye 

 picks up a picture, but the brain does the interpretive "seeing," and, in general, 

 the brain sees only what it knows. This means that past experience has a 

 great deal to do with what is seen. The whole point of adaptive coloration is 

 a play on the interpretive part of vision. 



Concealment — Cryptic Coloration 



In the case of concealment, adaptive coloration serves the purpose of making 

 the adaptively colored animal harder for its enemies to detect or harder for its prey 

 to notice. In other words, the clues by which detection of an object is made are 

 rendered inconspicuous. Methods of concealment are four in number: 



1. Color Resemblance. The most common method of concealment involves 

 colors and color patterns that match the background. The flatfishes Qcolor 

 photograph'), round sting rays (fig. 76) and the cowfish (/ig. 12) show this 

 admirably in their resemblance to substrate. The octopus is another notable 

 example of an animal that matches its surroundings. The red colors of 

 moderately deep-water or nocturnal animals might be adaptive, making 

 these species appear black. Several deep-sea animals and the larvae of eels, 

 tarpon, bonefish and ladyfish are almost completely transparent, which is a 

 protective lack of coloration that imitates the transparency of ocean water. 



Some animals change colors throughout life to match their changing 

 environments. Cott gives the examples of the flying fishes, which are brown 

 when young in sargasso weed and blue when adult in the open sea, and 

 the sea slug, Aplysia Qcolor photograph), which changes from red when 

 it lives on red algae when young to olive-brown when it lives on brown 

 algae as an adult. Great numbers of bonv fishes and a few sharks are able 

 to change color, being, in general, of lighter coloration in open water over 

 a light bottom or near the water's surface and of darker coloration over a 

 dark bottom or near dark places. 



2. Obliterative Coloration. This adaption is encountered mostly in open-water 

 species and is explained by figure 11. It involves countershading, in which 

 the animal is darker above than below. This, in combination with 

 illumination from above, makes the animal look flat and inconspicuous. 

 Mackerels are excellent examples of this. The diver who has seen the 

 barracuda swim toward him like a ghost has seen another good example 

 of obliterative coloration. Countershaded fishes appear dark when seen 

 from above, and when seen from below appear light against the surface. 

 Most fishes are countershaded in addition to their other coloration 

 adaptations. 



3. Disruptive Coloration. In most cases, matching colors alone are not 

 enough to conceal an animal. Methods which break form and outline, 

 the greatest of all clues to identification, are very often employed. Stripes 

 or bars are effective in breaking outline as shown by figure 12. 



The jaw outline of many bottom-living predators is concealed by the 

 presence of fleshy, protectively colored tabs. Such is the case with toadfish, 

 anglers, stargazers, sculpins, and scorpion fishes. 



