Introduction, taxonomy, and general biology of abalone

Abalone are marine snails that belong to a group of invertebrates called molluscs, that also include common bivalves such as scallops, oysters, mussels, pippies, and cockles, as well as octopus, squid, and cuttlefish. Abalone have a moderate to heavily calcified snail-like, flattened shell. They belong to the exclusively marine family, Haliotidae and to the single genus-level taxon, Haliotis. There are 56 valid species, with 18 additional subspecies. Abalone shells are flattened, similar to limpets, and have little external signs of coiling. The shell has a wide opening for the body and a single row of respiratory pores along one side that are used in respiration, excretion, and reproduction. The flat body shape of abalone is important in reducing drag forces that are generated by waves that are typical of their shallow, exposed coastal reef habitat. Viewed from the ventral side, the internal anatomy is dominated by a large, flat, muscular foot, surrounded by a pigmented epipodium, which is a flat circle of tissue with sensory tentacles. On temperate and tropical shores, abalone occur from the low intertidal to a depth of about 30 m, especially in areas supporting seaweed beds, where adults are macroalgal herbivores. In most areas where abalone are common, they have formed the basis of important fisheries.