Growth of Juvenile Acanthaster planci (L.) in the Laboratory

Abstract

Seven juvenile Acanthaster planci were reared from fertilized eggs to sexual maturity in 18 to 21 months in the laboratory. Four-month-old juveniles, about 8 mm in total diameter, began to transform into coral predators from the prior herbivore stage that fed on encrusting coralline algae. The transition period lasted for about 1 month. Many juveniles were injured by coral polyps, which had been offered as food, shortly after the transitional period. Except for severely injured ones, all the coral-feeding juveniles grew steadily after recovering from the injuries and, when the animals were well fed, their growth curve was sigmoid. Mean growth coefficient for the early coral-feeding juveniles, growing exponentially, was nearly half that of the previous algae-feeding stage, and the coefficient value reduced rapidly as the juvenile grew near to maturity. Acropora nasuta and Pocillopora damicornis both sustained full growth of juveniles. However, the juvenile Acanthaster killed about twice as much coral mass of Acropora nasuta as of Pocillopora damicornis to gain the same amount of weight.