Diving with Spiny Oysters

Lanta Marine Life | Spondylidae

Spiny or thorny oysters can be easily spotted at nearly all of the sites during our high season Koh Lanta dive trips.

The many species vary considerably in appearance and are actually related to scallops, rather than oysters. Similar to oysters however, they live cemented to rocks, corals or other hard surfaces and are capable of producing pearls, depending on their environment.

This family has a very well developed middle mantle and nervous system, with sensory tentacles and multiple eyes around the shell edges. Spiny oysters have a ball and socket type connection between the two shell parts, rather than the more common toothed hinge of other bivalves.

Spiny oysters are filter feeders and can suck water into its gills to remove oxygen and food.

1 species found on this page:

Variable Thorny Oyster (Spondylus varians)

Variable Thorny Oyster

(Spondylus varians)

Spondylus varians @ Koh Haa

The variable thorny oyster Sphondylus varius is the largest of the spiny oysters, growing to a maximum diameter of around 20 cm.

The shell is of this species can be easily recognised because the main adult shell is white, with the bright red or yellow larval shell remaining at the joint end of the shell (the connection between the two sides). The larval shell is however difficult to see as the main shell is usually overgrown with algae and other life.