Purple Sea Urchin

Sea urchins and lobster in a crevice

Scientific name

Heliocidaris erythrogramma


The Purple Sea Urchin is a member of the family Echinometridae and possesses a hard exoskeleton with numerous sharp, solid spines that taper to a point. Body colour ranges from white to green, purple and black and the spines are typically different in colour. They have tube feet and the mouth is located on the underside of the body. Purple Urchins feed by actively grazing rock surfaces and by trapping algae or seagrasses.


Purple Sea Urchins can reach up to 14 cm in test (external skeleton surrounding the body) diameter.


Purple Sea Urchins are an endemic Australian species, which can are found in southern Queensland, NSW, Victoria, Tasmania, South Australia and Western Australia. They inhabit coastal waters up to 35 m in depth, but are most common in waters shallower than 10 m. As benthic animals, they are often found attached to rocky reefs, stones, seagrass beds, in crevices and burrows and on sandy mud bottoms. The species seems to prefer areas not fully exposed to wave motion.