Selenka, 1867
H. (Mertensiothuria) pervicax is a grey/brown sea cucumber, mottled above, with red-brown papillae ringed with white, and grey below with dark spots of tube feet. It is a hemicylindrical species, somewhat flattened below, with a medium-sized (to 300 mm), soft and pliable body, a smooth tegument, and thick, translucent cuvierian tubules (H. pervicax photo[/l]). [l][m]Glossary[/m][r]Spicule[/r]Spicules are rather poorly formed, buttons often like small beaded rods. This species many be found on reefs below rocks on flats.
Remarks: The distinction between fuscocinerea and pervicax is not too clear; however the latter does have quite reduced spicules. Another holothurian with spicules very like those of pervicax is sometimes encountered and may be a colour morph. It is a rich red/brown above and white below.