Thais orbita
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| Thais orbita (Martyn, 1784) |
Thais orbita, or the white rock shell, is a gastropod mollusc of the family Muricidae, endemic to southern Australia and the North Island of New Zealand. It is found intertidally and is quite common on rocky ground, both in sheltered waters and on the open coast.
Its favourite food is mussels, and it is capable of wedging shells open using the lip of its own shell.
The shell is large and strong to massive, ovate in shape. The sculpture is very variable, usually with a few broad low spiral ridges, separated by wider interspaces, bearing several spiral threads. In some shells the spiral ridges and grooves are massive with deep interspaces. The thick operculum is ovate-lunate.
Coloration is a dull creamy-white, sometimes obscurely spirally lined in light reddish-brown. The interior of the aperture and the parietal callus is also creamy-white. The lower part of the body and the siphon are reddish-brown, and the rest is white.
The egg cases are straight sided and flat topped, fitting together like honeycomb, and are often seen attached to rocks. They are cream coloured, often tinged with lilac.
Height is up to 118 mm, and width 73 mm
[edit] References
- Miller M & Batt G, Reef and Beach Life of New Zealand, William Collins (New Zealand) Ltd, Auckland, New Zealand 1973
- Powell A W B, New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1
- Glen Pownall, New Zealand Shells and Shellfish, Seven Seas Publishing Pty Ltd, Wellington, New Zealand 1979 ISBN 85467 054 8
