A Suggested Mechanism for Habitat Selection By the Juvenile Manini Acanthurus Triostegus Sandvicensis Streets

Abstract

AbstractThe Hawaiian manini, Acanthurus triostegus sandvicensis Streets, shows a continuing selection of habitat throughout juvenile life, and the selected habitat changes in character as the fish grows in size. Habitat selection of this kind is a complex type of choice behaviour in which the animal makes a selection from a number of (at least partly) configurational stimulus situations experienced separately over time. This sort of behaviour cannot be satisfactorily explained by reference to concepts of taxes or kineses. A mechanism is proposed to explain this process. It suggests that intensity of habitat exploration is regulated through a negative feedback mechanism by the character of the immediate environment with respect to the pertinent stimuli. A fish in an inadequate environment will show a high intensity of habitat exploration. One in an adequate environment will show a much reduced level of exploration. Twenty manini were exposed singly to four test environments of known relative value as habitats. Each fish received all four, and order of exposure was randomised. Analysis of thirteen components of behaviour showed that exploration did vary in the manner predicted. A control experiment showed that the nature of the holding environment prior to testing did not influence this variation. The variation in exploration was not a response to relative novelty of the test environments. The proposed mechanism is discussed as a general behaviour pattern. It seems an applicable approach to the study of habitat selection in other organisms.