Starfish - Sea Stars Life Cycle

Starfish or sea stars are capable of both sexual and asexual reproduction.

Starfish on divers glove

Sexual Reproduction

Sea stars are male or female. Fertilization is external and occurs when the sea stars release enormous numbers of sperm and eggs in the ocean. It is thought that they use environmental signals to trigger and co-ordinate the timing of gamete release.

The fertilized embryos are tiny, transparent and bilaterally symmetrical. They are swept along on the ocean currents for about two months where they form part of the zooplankton. They grow by consuming phytoplankton.

The developing sea stars then settle out of the zooplankton and develop radial symmetry.

Asexual Reproduction

Sea stars can develop from splitting off of an arm. Once detached, the arm will eventually grow into another independent sea star. The original sea star will regrow a replacement arm.

Website created by Jenny Stevenson - June 2006.