Life History & Behaviour

Reproduction

H. atra canoccur in either a gonochoric (male or female) or hermaphroditic form (male and female) (Harriot 1980).  Like many other species of sea cucumbers, it has two methods for reproduction: sexual and  asexual (Harriot 1980).  Sexual reproduction involves the release of sperm and eggs into the water column where the eggs are fertilised (Ruppert et al. 2004).  H. atra are a fissiparous species meaning that they are able to change their mode of reproduction at some point during their life (Thorne et al. 2012).  H. atra generally begin life as asexually reproducing individuals, when they are smaller sizes, and then progress to a larger, sexually reproducing stage (Harriot 1982). 

The asexual form of reproduction is known as transverse binary fission (one animal breaks in half and two new animals form) (Harriot 1982).  Asexual reproduction in H. atra is most commonly observed in: winter (Uthicke 1997) and in shallow, reef-flat areas (Harriot 1982).  Studies have demonstrated that asexual reproduction in H. atra is important for maintaining the population (Uthicke 1997).