44 UNDERWATER GUIDE TO MARINE LIFE 



2. Conspicuous Localized Characters. In some cases, it is not the whole 

 animal that is advertised but some specific part of it. Lumped in this 

 category are a wide variety of fascinating examples, most of which involve 

 some sort of misrepresentation or deception and which can almost be 

 thought of as being a sort of concealment-advertisement combination, for 

 in making one part of a body conspicuous, the other parts are made much 

 less so. 



The one sort of exception to this general rule is exhibited by animals 

 which conspicuously advertise a particularly dangerous part of their bodies. 

 No deception is involved here. The sharp, preopercular spine of angelfishes 

 is usually a bright yellow. The poisonous spiny dorsal fin of the European 

 weaver, Trachinus, is a conspicuous black. The lancetlike white spine on 

 the caudal peduncle of the blue tang contrasts with its otherwise blue 

 body. Electric rays frequently have ocellar spots on their backs as warning 

 marks. 



The other purposes of conspicuous localized characters are several and 

 involve misrepresentation as stated above. First, conspicuous contrasting 

 colors may serve to startle predators. This is a protective device involving 

 bluff. The batfishes spread their pectoral fins to show a startling black and 

 white banded pattern when threatened. Sailfishes are known to erect 

 their huge dorsal fins when fighting or excited, and they may thus alarm 

 aggressors. 



Second, conspicuous colors may serve to lure prey to the most dangerous 

 part of an animal. The angler fishes use their first dorsal spine as a lure 

 to attract prey, and the stargazers have a similar lure inside their mouths. 

 In both of these cases, the lures are wiggled to make them even more 

 conspicuous. Anemones have attractively colored stinging tentacles which 

 lure small fishes to their deaths. 



Third, conspicuous characters may serve to distract attention awav from 

 the most dangerous part of an animal. The cuttlefish, Sepia, and probably 

 other squids as well, exhibits rapid waves of color on the posterior part 

 of its body, which draw attention away from the tentacles. When the 

 cuttlefish draws close to its prey, these relatively inconspicuous tentacles 

 are shot out, and the capture is made. 



Fourth, colors and conspicuous marks are often used to misrepresent 

 the posture or position of an animal or to direct attack to less vulnerable 

 parts of the body. The combination of an eye stripe and an eyelike spot 

 near the tail of the four-eyed butterfly fish creates the impression that 

 this fish is swimming backwards. Longitudinal stripes through the bodies 

 of such fishes as shark-suckers, cobia, and the rainbow runner make these 

 animals appear to stand still while they are actually moving speedily 

 forward. Squids, octopuses, and some sea slugs QAflysia^ emit clouds of 

 inky fluid when annoyed, which confuse an enemy and mask their 

 retreat. Some animals leave parts of their own bodies behind to confuse 

 enemies. This habit is called "autotomy" and is well known in the cases 

 of many lizards, including the glass "snake," which can discard its tail at 

 a moment's notice, then grow a new one later. In the sea, the crustaceans 

 are the best-known practitioners of autotomy. Many of them have a special 

 autotomous joint where a limb may be broken off. This limb then wiggles 



