Dicathais orbita (Gmelin, 1791)
Abundant throughout the Solitary Islands Marine Park. Endemic to Australia where it ranges from around Exmouth in Western Australia south through South Australia and around Tasmania, north through New South Wales to central Queensland, and including Lord Howe Island.
Frequents rocky reef platforms and reefs to depths of at least 10 m.
Shell shape varies with location, the widest shells with the deepest grooves occur in New South Wales while more pear shaped shells with low ridges occur in exposed habitats. Feed on mussels, barnacles and snails by drilling a hole through their shell with a specialised radula and sucking out the contents, controlling numbers of barnacles and mussels in many areas. Sexes are separate, the female laying multiple egg capsules which are attached to the substrate. The young progress to the veliger stage in the capsule after which they emerge and become planktonic, eventually settling. Known to live for at least 20 years, commonly 60 mm, grow to 75 mm.
Graham J. Edgar. Australian Marine Life, 2nd Edition, 2008. Reed New Holland Publishers. p.301.
Atlas of Living Australia website at https://bie.ala.org.au/search?q=dicathais+orbita. Accessed 05/11/2018.