The hooded oyster, otherwise known as the Natal rock oyster is a species of oyster found throughout the Indo-Pacific.
It has a very irregular and inconsistent shape and appearance: it can be at times circular, or roughly oval. Its outline tends to be irregular, and its colour may be purplish-brown to dark purple. Its surface may also vary; it may have spiny ribs or be smooth. Measuring up to 6 centimeters, it has thick and solid valves, with the upper being smaller than the lower valve. The lower valve is attached to the substrate. The species is often covered in encrusting pink coralline algae.
The hooded oyster typically prefers rocky habitats and is also considered part of the fouling community – communities of organisms found on artificial surfaces such as the sides of docks, marinas, harbors and boats. S. cucullata is also found on the roots of mangrove trees in large groups. Like other bivalves it is a filter feeder, ingesting phytoplankton by pumping water through its gills.
The status of the hooded oyster S. cucullata is not currently assessed on the IUCN Red List of Threatened Species. Due to its population size and range, as well as adaptability in various habitats, the existence of the species is not currently threatened. As with other species inhabiting mangroves, however, the hooded oyster may suffer local population declines due to habitat destruction and loss.
These types of oysters can be used as bioindicators as they accumulate heavy metals in their tissues and are also considered a rather efficient biofilter (efficiently removes excess nutrients etc).