Editing Sea cucumber (section)

=== Reproduction ===
[[File:Haeckel Amphoridea-12.jpg|thumb|upright=0.8|"Auricularia" larva (by [[Ernst Haeckel]])]]
Most sea cucumbers reproduce by releasing [[sperm]] and [[ovum|ova]] into the ocean water. Depending on conditions, one organism can produce thousands of [[gamete]]s. Sea cucumbers are typically [[dioecious]], with separate male and female individuals, but some species are [[Sequential hermaphroditism|protandric]]. The reproductive system consists of a single [[gonad]], consisting of a cluster of tubules emptying into a single duct that opens on the upper surface of the animal, close to the tentacles.<ref name=IZ/>

At least 30 species, including the red-chested sea cucumber (''[[Pseudocnella insolens]]''), fertilize their eggs internally and then pick up the fertilized zygote with one of their feeding tentacles. The egg is then inserted into a pouch on the adult's body, where it develops and eventually hatches from the pouch as a juvenile sea cucumber.<ref>Branch GM, Griffiths CL, Branch ML and Beckley LE(2005) ''Two Oceans'' {{ISBN|0-86486-672-0}}</ref> A few species are known to brood their young inside the body cavity, giving birth through a small rupture in the body wall close to the anus.<ref name=IZ/>