Food selection and learning in the crown‐of‐thorns starfish,Acanthaster planci(L)

The Crown‐of‐thorns starfish Acanthaster planci, shows selection for the species of coral on which it feeds. On contacting a coral, the starfish may settle on it, or it may show an avoidance response and move away. The probability of the starfish showing feeding behaviour depends on the species of coral, and the past experience of the starfish with that species. Corals with powerful nematocyst action tend to be avoided, but species on which the starfish has successfully fed become increasingly acceptable. By contrast while starfish will initially attempt to feed on plaster‐of‐Paris tablets impregnated with certain feeding inducers extracted from coral, with repeated presentation this response wanes. These forms of positive and negative adaptation of the response to food associated stimuli, we attribute to an ingestive conditioning. In this way the starfish tends to form a search image for some of the commonest species of coral, and this in turn has ecological effects upon the coral assemblages among which A. planci lives.