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You are here:   OldClasses > 2012 > Stichopus horrens | Chantelle Morrison



Stichopus horrens (Selenka 1867)

Peanutfish, Flemfish, Selenka's sea cucumber

Chantelle Morrison (2012)



Fact Sheet



Physical Description


Life History & Behaviour

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Conservation & Threats

References & Links

Evolution & Systematics

The family Stichopodidae contains 32 species in 9 genera, genetics has helped to further define the 5 genera that could be separated based on morphology (Byrne et al., 2010).

The complete mitochondrial DNA of Stichopus horrens has been sequenced and can be accessed through GenBank (Fan et al., 2012). It consists of 16 257 base pairs and genetic barcoding has been developed so that differentiation can easily occur between commercial species, when it is so difficult based on morphological characteristics alone (Uthicke et al., 2010). S. horrens and the closest sister group (S. monotuberculatus) diverged less than 1mya (Byrne et al., 2010).

Figure 1: The phylogenetic relationships of species within the Stichopus genus. Adapted from: Fan et al, 2012.

Figure 2: The phylogenetic relationships of genera within the family Stichopodidae. Adapted from: Fan et al, 2012.

The closest sister group to the Holothurians are the Echinoids (Smith, 1988), with support from genetics and the fossil record (Smith, 1988). Sea cucumbers do not fossilize well, however two fossils have been found, one from the Upper Carboniferous, the second from the Lower Devonian (Smith, 1988). It is thought that two genera may have been the ancestors to the extant groups of Holothurians, these are Rotasaccus and Palaeocucumaria (Smith, 1988).

Rotasaccus had a hard body wall (made of spicules which are similar to those found today) and tube feet (although plated) like a sea cucumber, but also an Aristotle’s lantern like modern echinoids (Smith, 1988). Palaeocucumaria also had a hard body wall made of spicules, plated tube feet, and an oral feeding tube (Smith, 1988). It seems that this paleontological evidence would support the relationship between Ophiuroids and Holothurians.