Reproduction
The sexes are separate in most echinoderms. In most groups, gonads located in the body cavity shed sperm or eggs directly into the water. Gametes (sperm and eggs) do not survive long in the water, so many species, all individuals spawn at the same time to ensure fertilization. The fertilized egg develops into a planktonic larva (specific to each group). Those that do not make planktonic larvae brood their offspring in special pouches or under the body.
Some sea stars, brittle stars and sea cucumbers reproduce asexually by the separation of the central disk or body into two pieces. The resulting halves then grown into complete individuals. The ability to regrow lost or damaged body parts is called regeneration and is highly developed in echinoderms.
Below, you can see the larva of a brittle star.
Some sea stars, brittle stars and sea cucumbers reproduce asexually by the separation of the central disk or body into two pieces. The resulting halves then grown into complete individuals. The ability to regrow lost or damaged body parts is called regeneration and is highly developed in echinoderms.
Below, you can see the larva of a brittle star.