Critter of the Week: Histocidaris – The explosive urchins?
The Cidaroida is an order of very spiky and robust regular sea urchins, which can resemble something like a sputnik satellite or an underwater mine to the uninitiated.
An unlucky snorkeler from Sydney, Australia misidentified a species of shallow water cidarid as an unexploded underwater mine and alerted local police. The story quickly becaome national news. Fortunately experts were able to tell it was nothing to be worried about. Specialists from an echinoderm forum think that what the snorkeler saw was likely a species of Phyllacanthus.
The stunning purple urchin
In New Zealand we have three families, 13 genera, and 18 described species of Cidaroida. One particularly stunning deepsea variety is Histocidaris purpurata (Thomson, 1872). This species is supposedly quite widely distributed from the North Atlantic to the South West Pacific (Kroh, 2016), but is rare in our collection. We have five records of H. purpurata from 788–1105 m deep from the Southern Kermadec Seamounts to the lower East Coast of the North Island of New Zealand.
- Read the news report about the Australia snorkeler who misidentified the sea urchin for an underwater mine
- More information and keys can be found for Histocidaris and other species of sea urchin in the British Natural History Museum's Echinoid directory
- Kroh, A. (2016). Histocidaris purpurata (Thomson, 1872). In: Kroh, A. & Mooi, R. (2016). World Echinoidea Database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=513337 on 2016-05-11
- Smith, A. B. & Kroh, A. (editor) 2011. The Echinoid Directory. World Wide Web electronic publication. http://www.nhm.ac.uk/research-curation/projects/echinoid-directory [accessed 11 May 2016].