How to predict what an animal will do next

248

ANIMAL

BEHAVIOUR,

VI,

3-4

HOW TO PREDICT WHAT AN ANIMAL WILL DO NEXT S. A . ALTMANN The Biological Laboratories, Harvard University, Cambridge, Mass ., and National Institute Neurological Diseases and Blindness, Bethesda, Maryland

What an animal does at any moment depends in part upon preceding behavioural events . Therefore, an attempt to maximise the accuracy of predictions of behaviour must take into account the probabilities of sequences of behaviour. In order to represent the complex sequences of events that occur among social animals, a mathematical model, based on com-

of

munication theory, is introduced . Some advantages of the model over traditional methods of description are pointed out and some ramifications of the model are briefly described . The practicability of research based upon the model has been demonstrated by a study of social organisation in free-ranging rhesus monkeys . (15 minutes) .

OBSERVATIONS ON THE BEHAVIOUR OF THE POMACENTRID FISH Amphiprion percula, COMMENSAL OF THE ANEMONE Stoichactis BY

D . DAVENPORT

AND

K . S . NORRIS

University of California, Santa Barbara College and Marineland of the Pacific

The process is described whereby an Amphiprion percula, unacclimated to the host Stoichactis kenti and newly introduced into an aquarium

containing the host, effects its association . Evidence is presented that the protection of the fish is at least in part effected by the secretion of a mucus from the skin of the fish which specifically raises the threshold of discharge of its host's nematocysts . This factor is not heat stable and

is not present in the muscle of the commensal fish . It is effective in preventing discharge of nematocysts from isolated tentacles under mechanical stimulation, but does not alter the threshold of discharge under electrical stimulation . The physiological effect upon each other of contact between the partners is discussed . (Illustrated, 2" x 2", 15 minutes) .

THE INFLUENCE OF SOCIAL DOMINANCE ON EXPLORATORY BEHAVIOUR : A COMPARISON OF SOME FISHES AND ARTHROPODS F . D . KLOPFER Department of Psychology, State College of Washington, Pullman, Washington

The exploratory behaviour of six species of benthic marine fishes, one freshwater, one terrestrial and one marine arthropod species is compared . Individuals differing in social dominance were tested alone and in pairs in a limited relatively homogeneous tank . The following conclusions seem justified : 1 . Differences among species represent schooling vs . territorial characteristics . 2 . Pairings of schooling fish vs . "alone" results in increased rate and magnitude of exploration . 3. With pairings in other species, (a) Dominant animals explored more, sooner,

and defended a larger territory away from the starting point ; (b) Submissive animals explored less, later, and defended a small territory near the release point ; (c) Both groups explored more rapidly, were more "emotional" and responded sooner to food when paired than when alone . In tests where shelters were provided, dominant animals spent less time in shelters than submissive, and less when paired than when alone . Results were discussed in relation to theoretical formulations of drive and anxiety . (Illustrated, 3J" x 4") .