Fig. 1.  Location of gonad in coelomic cavity and gonopore(s)

Courtesy Cindy Young, University of British Columbia

Sexes are separate in temperate-dwelling sea cucumbers.  The gonad is single and mop-like in form (Fig. 1).  Gametes are released from one or several gonopores that are usually located on the membrane between mouth and tentacle ring.  Fertilisation is external and leads to a non-feeding auricularia larva that may spend an extended time in the plankton before settling.