divepix - Atlantic Thorny Oyster

Atlantic Thorny Oyster

Aspect:	All is usually seen of Spondylus americanus is the typical shape of two clam-like half shells (called valves) covered in algae or other neighbouring organisms like sponges for better deception and, when open, a white-spotted brown mantle. If they were to be seen uncamouflaged, the valve surfaces would reveal amazing flattish, sharp-edged spines growing radially and horizontally with some overhanging the edges of the valves (as can be seen on some of these photographs).
Population:	Common, but requires an exercised eye to spot, particularly when shut.
Notable feature:	Brown mantle with white spots.
Environment:	Atop rocks, on the side of boulders, wreck surfaces or even old, unmoved, mooring lines as evidenced here.
Behaviour:	Will promptly shut if approached too closely (it has a couple of "eyes" made of photosensitive cells to detect a shadow cast by an approaching predator - typically an octopus). Feeds on plankton.

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