BIOLOGY OF THE SEA-HOW THEY LIVE 43 



color matches the open water, showing color resemblance as well. The sergeant 

 major has bars for disruptive coloration, color phases which match environment, 

 and countershading. The octopus is one of the few animals that shows only 

 one method, color resemblance, though even in this case, its sometimes 

 noticeable blotchings could perhaps be interpreted as disruptive coloration. 

 The round ray is both protectively colored and flat to eliminate shadow. These 

 examples should serve to illustrate the point. Do not look for one simple answer 

 to concealment; it is most often a combination of interplaying factors. Conceal- 

 ment of one part of the body may even be combined with advertisement of 

 another part. For example, the four-eyed butterfly Hsh conceals its real eye and 

 advertises a posterior false eye. 



Advertisement — A posemotic Coloration 



Diametrically opposed to concealment is advertisement. Some animals are 

 conspicuously colored either to serve as a warning or as an aid for food-getting. 

 Bright colors and striking patterns by themselves do not reveal to us whether 

 an animal will be conspicuous or not. Rather, how the animal looks to the other 

 members of its community is again the important criterion. Animals that 

 advertise are frequently sluggish and stand their ground, especially when they 

 are protected by having poisonous spines or flesh. They are sometimes gregarious, 

 so that their conspicuousness is reinforced by their numbers, and they usually 

 display themselves freely. 



There are two aspects to advertisement, action and color pattern. Sometimes 

 these work alone, but they usually go hand in hand. Animals that are conspic- 

 uous-looking in their environment also act in a conspicuous way. 



1. Warning Colors. Conspicuous colors are sometimes taken on by animals 

 to advertise the fact of their ill-tasting flesh, poisonous flesh, poison spines, 

 or anything else about them that is definitely distasteful or dangerous. 

 These animals travel more or less with impunity and with little fear of 

 attack. This, of course, involves learning on the part of the predators 

 which avoid attacking these animals. By advertising themselves, recognition 

 is made easier, and there is reinforcement of dangerous qualities by striking 

 appearance. Many sea slugs (nudibranchs) are very brightlv colored to 

 advertise their distastefulness iColor Plate 10^. 



Warning display goes hand in hand with warning colors. The porcupine 

 fish inflates not only in order to appear larger, but also as a warning of its 

 dangerous spines and poisonous flesh. The sculpins erect their preopercular 

 spines when molested. The squids and octopuses cause waves of color 

 to pass over their bodies, causing hesitation on the part of predators. 

 Toadfishes utter a grunt probably as a warning to advertise the power of 

 their jaws. 



Some warning colors are adventitious and the result of symbiosis. Thus, 

 the man-of-war fish achieves protection due to the warning colors or form 

 of the Portuguese man-of-war's tentacles. Some Indo-Pacific demoiselles 

 live in the protection of stinging anemones. One crab uses a live anemone, 

 held in its claws, as a warning to predators. 



