COLOR AND PATTERN IN ANIMALS 



411 



utter indistinguishability of the larvae is something that needs 

 to be experienced to be fairly realized. 



Far more striking are those cases of protective resemblance 

 in which the animal re- 

 sembles in color and shape, 

 sometimes in extraordi- 

 nary detail, some partic- 

 ular object or part of its 

 usual environment. Cer- 

 tain parts of the Atlantic 

 Ocean are covered with 

 great patches of seaweed 

 called the Gulf weed (Sar- 

 gassum), and many kinds 

 of animals fishes and 

 other creatures live upon 

 and among the algae. No 

 one can fail to note the 

 extraordinary color resem- 

 blances which exist be- 

 tween these animals and 

 the weed itself. The gulf 

 weed is of an olive-yellow 

 color, and the crabs and 

 shrimps, a certain flat- 

 worm, a certain mollusk, 

 and certain little fishes, 

 all of which live among 

 the Sargassum, are exactly 

 of the same shade of yel- 

 low as the weed, and have 

 small white markings on 

 their bodies which are 

 characteristic also of the 

 Sargassum. The mouse- 

 fish and the little sea- 

 horses, often attached to 



the Gulf weed, show the same traits of coloration (Fig. 252). 

 The slender grass-green caterpillars of many moths and butter- 

 flies resemble very closely the thin grass blades among which 

 they live. The larvae of the geometrid moths, called inch worms 



FIG. 253. A Geometrid larva on a branch. 

 (The larva is the upper right-hand projection 

 from the twig.) 



