The Chromatophore System of the Crawfish Orconectes clypeatus

Abstract

In spite of the fact that much information is available concerning crustacean pigmentary systems, data on crawfish chromatophores are scanty. The pigmentary systems of only two species of crawfishes have been investigated in detail and both systems proved markedly different from one another. Brown and Meglitsch (1940) found that the red pigment of the crawfish Orconectes immunis on a white background concentrated maximally and the white pigment dispersed maximally. The pigmentary were reversed when the crawfish was placed on a black background. The sinus gland in the eyestalk of Orconectes immunis produced two chromatophorotropins, white pigment dispersing and red pigment concentrating. McVay (1942), also working with Orconectes immunis, demonstrated that the central nervous organs were potent sources of red and white pigment concentrating hormones. Background responses of the dwarf crawfish, Cambarellus shufeldti, were the same as those of Orconectes immunis (Fingerman, 1957a). However, the endocrine control of the chromatophores of Cambarellus was different from that of Orconectes immunis. The eyestalks of Cambarellus produced appreciable quantities of white pigment dispersing and concentrating hormones and a red pigment dispering factor. The presence of a red pigment concentrating hormone in the eyestalk was also indicated by the results. The central nervous system was a source of significant quantities of four principles, red and white pigment dispersing and concentrating hormones. The behavior of red and white chromatophores on isolated portions of the carapace of Cambarellus shufeldti was investigated by Fingerman (1957b) to determine the resting states of the chromatophores. The red pigment had an inherent tendency to concentrate nearly maximally and the white pigment to disperse nearly maximally when the red and white chromatophores were no longer under the influence of blood-borne factors. Responses of isolated chromatophores of Cambarellus to extracts of eyestalk and central nervous organs were complicated by the inherent tendencies of the white pigment to disperse and the red pigment to concentrate and were not the same as responses to extracts injected directly into the body cavity of Cambarellus. Experiments that involved reciprocal blood transfusions between Cambarellus adapted to black and to white backgrounds have shown