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Crassostrea echinata (Family Ostreidae)

Spiked Oyster

Distribution

Distribution:

The Spiked Oyster is restricted to eastern Queensland, occurring on the shore and coastal islands protected behind the Great Barrier Reef. It ranges from Gladstone, Qld to Thursday Island and may extend through the Indonesian Archipelago to Malaysia (QLD).

Features:

The Spiked Oyster is a large, variable oyster, with a long, rough, oval-shaped outline. Its two valves are unequal in shape. Its lower valve is deep, with eight or nine deep ridges in those that occur in exposed locations and shallow ridges in those from protected areas. The upper valve is flattish, forming an upraised lip in older, mature shells. There is a distinct central hump between the hinge and the lip. The distinctive young ones have up to 24 strong spines extending vertically from the upper valve surface, while the lower valve is fluted. In older shells these distinctive spines have been broken off, especially if they have surf waves crashing down upon them.

The upper valve is bluish or purple-black with a slate-grey patch near the hinge. The muscle scar is greenish white to white, although there may be a lack scar on the upper valve. Eroded shells are all slate-grey, except for a black band inside the upraised rim.

Ecology/Way of Life:

This is an intertidal oyster found on rocks and mangroves on shores that may be covered by a light cover of mud. Some may also be under the influence of saline to brackish water.

Preferred Image

Interaction with Humans/Threats:

The Spiked Oyster has a restricted range behind the Great Barrier Reef. It is difficult to know if European farmland overcropping has lead to excessive soil erosion and the overuse of fertilisers on farmlands. These two factors have changed the ecology of the large freshwater rivers in the region. The farming practices may produce higher nutrient levels and excess silt and mud to be deposited on the rocky ocean shores where these nerite species live.

Other Comments:

Crassostrea (Saccostrea) echinata , Quoy & Gaimard, 1834. Crassostrea comes from two words; crass comes from the Latin word crassus, meaning gross, thick, dense or stupid, while ostrea comes from the Latin word ostrea, or the Greek word ostreon that mean oyster. Echinata comes from the Greek word echinos, meaning hedgehog.

Further Reading:

Davey, K. (1998). A Photographic Guide to Seashore Life of Australia. p. 126, New Holland Press.

Thompson, J.M. (1954). The Genera of Oysters and the Australian species. Aust. J. Mar. Freshwater Res. p. 133-168.

Acknowledgments:

Text, map and photograph by Keith Davey.

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Images and Multi-media:  
Attached Image  
image/jpeg 116492 bytes Spiked Oyster
Distribution Map  
image/gif 921 bytes Distribution of Spiked Oyster

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