About Atrina squamifera (G.B.Sowerby I, 1835)
This species, Atrina squamifera, has a large, fragile shell that can reach a total length of up to 390 mm. 6 to 12 ribs run longitudinally along its shell, and each rib bears translucent, cup-shaped projections. The shell cannot fully close at its posterior end, allowing the dark-rimmed white internal flesh to be visible. This species occurs along the coast from Saldanha Bay to Port Alfred, and lives in subtidal areas down to at least 35 m depth. Atrina squamifera, commonly called the horse mussel, is a filter feeder. It most commonly stays buried vertically in mud or sand substrates, though individuals have also been observed growing on the wooden decks of two trawler wrecks, the Orotava and the Princess Elizabeth, located in Smitswinkel Bay. The shell of Atrina squamifera is often heavily overgrown by other invertebrates. Small pea crabs and shrimp often live inside its mantle cavity, feeding on food that the mussel has filtered from water through its gills.
