Spawning pheromone in crown-of-thorns starfish

LARGE aggregations of the crown-of-thorns starfish Acanthaster planci L have destroyed a high proportion of the coral on certain Indo-Pacific reefs. We report that gamete release by one A. planci induces other ripe starfish to spawn; similar behaviour has been observed in certain other echinoderms^1,2. During natural spawning a pheromone is released from the gonad, which synchronises spawning in neighbouring animals and also induces starfish movement towards the spawning individual. Using a Y maze to study chemoattraction in spawning starfish, we have attempted to isolate and characterise the active gonad component.