Holothurians have a single gonad, and most are dioecious. Although most spawn and are fertilized externally, there are approximately thirty brooding species. Some capture eggs with tentacles, placing the eggs at the sole or dorsal body surface for incubation. A few have internal fertilization and development, where hatched young are released.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); simultaneous hermaphrodite; sexual ; fertilization (External , Internal ); ovoviviparous ; oviparous
While most species release eggs and have no perental investment after spawning, some species brood eggs. A few species also brood the eggs internally until they hatch.
Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Female, Protecting: Female)