Egg-shaped Sea Urchin
The Egg-shaped Sea Urchin has a very restricted distribution in south-eastern Australia. It ranges from Cape Liptrap, central Vic and Tas to Spencer Gulf, SA (VIC, TAS, SA).
The Egg-shaped Sea Urchin is a globe-shaped sea urchin that has dark primary spines, white secondary spines, and orange-tipped tube feet. Its diameter may be 50-60 mm.
In colour it has a creamy-white to olive-green test (the oval body). Its height is equal to or larger than its width, with a slight peak on its top surface, covered with small tubercles. The greenish to black primary spines are short, being only 5 mm long. They are finely striated, slightly flattened and widened at the spine tips. These are evenly spaced over the globe-shaped test. Its white secondary spines are slender, usually shorter, but some still grow to 5 mm in length. Patches occur where spines are missing, caused by erosion.
Amblypneustes may be distinguished from Holopneustes spp. by having a single primary spine at the edge of each of the test plates with holes for the tube feet (the ambulacral plates). Holopneustes species have a primary spine at the edge of every second or third ambulacral plate. This is most easily seen in dead and broken sea tests (Edgar, 1997).
Ecology/Way of Life:
The Egg-shaped Sea Urchin occurs at low tide level and below to 70 metres. It is occasionally found in shallow water and rock pools, usually suspended amongst algae fronds.
Interaction with Humans/Threats:
This sea urchin has a very limited distribution range, limited to the western half of Bass Strait to Spencers Gulf, SA. It could be affected if there was an extensive oil spill in Bass Strait.
Amblypneustes ovum, Lamarck, 1816. Lamarck originally named this species Echinus ovum, but L. Agassiz renamed it Amblypneustes ovum in 1841.
Amblypneustes comes from the Latin word, ambulare, to walk about, and the Greek word pneuma, meaning wind or breath. In this case it relates to its tube feet being worked pneumatically. Of course, this is not so, the flexible walking tubes are operated hydraulically, using fluid pressure. Ovum is a Latin word meaning egg.
Clark, H. L. (1946) The Echinoderm Fauna of Australia; Its Composition and its Origin. Carnegie Institution of Washington Publication 566, Washington D.C. p.318.
Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. New Holland Press, p.133, Sydney.
Edgar, G.J. (1997). Australian Marine Life: the plants and animals of temperate waters. p.361, Reed.
Marine Research Group of Victoria (1984). Coastal Invertebrates of Victoria: An atlas of selected species.p.147, Museum of Victoria.
Shepherd, S. A. & Thomas, I. M. (1989). Marine Invertebrates of Southern Australia. Pt. I. p.446, South Australian Govt. Printer.
Text, map & photograph by Keith Davey.
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