Pored Sea Urchin
This species ranges across southern Australia from central Victoria across South Australia and south-western Australia to Fremantle. (VIC, TAS, SA, WA)
The Pored Sea Urchin is a distinctively coloured, globe-shaped sea urchin. It is usually slightly wider than it is high, and mildly flattened on the ventral side. In adults the shape may be partially pentagonal. It may grow to 70 mm across.
It has a greenish-grey test that is composed of ten sections that extend from the top to the bottom of the animal. The anus is at the top while the mouth is at the bottom. Five alternate plates have numerous holes through which the tube feet protrude. There are bumps, called tubercles, all over the test that fit into the socket at the base of each spine. This ball and socket arrangement allows the spines to move around. The primary spines occur in distinct rows. They are short (2-3 mm) and thick, with a blunt to knob-shaped end. The spines are mostly green, with bright red tips. The tube feet are purple. . The secondary spines are smaller and are not so ordered. Many spines show evidence of regrowth. The pore zones are dark green. The pore zones are very wide, arranged in irregular vertical series. This is a distinctively coloured urchin.
Ecology/Way of Life:
The Pored Sea Urchin occurs at low tide levels and below to depths of 3-10 metres. It may be seen in shallow water, channels and in rock pools. It is usually attached to algae. Sea Urchins are micro-algae feeders. They have a structure called Aristotle's lantern in the mouth. At the centre of the feeding structure are five teeth that come together like a bird's beak. These strong teeth allow the urchin to graze on micro-algae which coats the rock surfaces. This feeding structure can be extended from and pulled back into the mouth to aid feeding. The Pored Sea Urchin is often observed after storms washed up and stranded on the beach.
Interaction with Humans/Threats:
Often observed stranded on the shore after storms.
Bennett, I. (1987) W.J. Dakin's classic study: Australian Seashores. p. 361. Angus & Robertson.
Davey, K. (1988) A Photographic Guide to Seashore Life of Australia. p. 134. New Holland Press.
Edgar, G.J. (1997) Australian Marine Life: the plants and animals of temperate waters. p. 363. Reed.
Marine Research Group of Victoria. (1984) Coastal Invertebrates of Victoria: an atlas of selected species. p. 148. Museum of Victoria.
Shepherd, S.A. & Thomas, I.M. (1989) Marine Invertebrates of Southern Australia. pt. I. p. 448. South Aust. Govt. Press.
Text, map & photograph by Keith Davey.
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