Color Pattern and Habitat Differences Between Male, Female and Juvenile Giant Kelpfish (Blennioidei: Clinidae)

The giant kelpfish, Heterostjehus rostratus occurs in three color morphs; red, brown, and green, which vary in shade according to number of melanophores. Color morphs were usually collected from plant habitats matching their colors. Frequencies of the color morphs were linked to sexual dimorphism; adult males are brown (infrequently olive green) and adult females exhibit all three morphs. Juveniles are either brown or green and not sexually dimorphic. In addition to color differences between the sexes, adult males and females display different melanin patterns. These patterns are apparently used for intraspecific communication and cryptic coloration. Brown males are distinguishable from brown females by their sexually dimorphic melanin patterns. Melanin patterns, unlike coloration, change (often rapidly) during courtship and territorial displays. Adult males and females occupy plant habitats that differ in depth, predominant color, and species composition. The brown males closely approximate color of the plants where the nests they guard are found. Females occupy other habitats, including red algae, green surfgrass, and other species of brown algae. Females venture away from matching habitats during the spawning season to reach male territories.