Anasteidae

Anasteidae is a family of marine bivalve mollusks, commonly known as saddle oysters or saddle shells. These animals are characterized by their unusually flattened, irregular shells that are often asymmetrical. The two valves, or halves of the shell, are typically unequal in size and shape, with one valve being more convex and the other flatter. This adaptation allows them to fit snugly into crevices and onto various substrates in their marine environment.

The Anasteidae are epifaunal, meaning they live on the surface of the seabed rather than burrowing into it. They are found in temperate and tropical waters worldwide, often inhabiting rocky shores, coral reefs, and the undersides of larger marine organisms like shipwrecks or submerged objects. Their diet consists of plankton and other small organic particles filtered from the water column using their gills. Reproduction in Anasteidae is typically sexual, with external fertilization being common. The larval stages are planktonic before settling to the seabed to metamorphose. While not commercially significant for consumption, their ecological role as filter feeders and as habitat for smaller organisms is noteworthy.