Chromatophores and Color Change 



679 



By means of their special type oF chromatophores the cephalopods arc 

 able to show more rapid color changes than other animals. 



In animals other than the cephalopods, the chromatophores are single cells 

 (e.g., in most vertebrates) or closely associated groups of cells or s\nc\tia 

 (e.g., in crustaceans). These were once thought to be ameboid cells, con- 



Fig. 255. A series oi photographs of a single white chromatoi^hore ot Pcilncniunclcs as 

 its pigment tully concentrates in response t(^ a black backgrounti, antl then re ihsperscs i 

 on return ot the animal to a v\'hite background. From Brown."' 



traction of whose processes resulted in a concentration of the pigment mass 

 into a small sphere, and whose e\tcnsi\e jiscudopodial iModuction rcsiihcd in 

 a broad dispersal of the pigments. Nov\ it is generally considcrctl that the 

 chromatophore has a permanently arborizing iorm, and that the pigment 

 granules either become concentrated into the chromatophore center to h)rm 

 a* punctate mass or become dispersed to \ar\ing degrees through ihe in 

 tricately branching structure"- to impart color to the macroscopic appear- 

 ance of the animal. Matthews and others ha\e reported obserxing branches 

 of chromatophores whose pigment was in the punciate condition. .Also sup- 

 porting this \'iew has been the demonstration of the striking similarity, e\en 

 to the minute terminals of a chromatophore, alter pigment dispersal on t\\<i 

 different occasions--'"- '^*- ""' (' 'M- -5S;. 



in typical details of form, pignients, and reactions, however, each ani- 

 mal, species, or group has its ow n chromatojihoral peculiarities. C hromato 

 phores are known as monochromatic, dichromatic, or polychromatic, de 

 pending on v\'hether they possess one, tw(\ or niore kinds of pigment. 1 he 

 crustaceans commonly possess di- or iiolyclironiatic chi-oi-natophores, with cich 

 pigment typically dispersing out into its own processes and, when con 

 centrated into the chroiiiatophore center, [possessing its own distinct indi 

 viduality. In fact, in the responses oi the crustacean chromatophore svsteni 

 to colored backgrounds the sewral pigments within a single chrom,ito|ihore 

 may show a considerable degree of indcjxndencc ol one another.-' 



