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Gastropods

Abstract:

The group includes abalone, conchs, limpets, nudibranchs, sea hares, slipper shells, slugs, snails, and whelks. The archaeogastropods exhibit a flattened appearance compared to other members of the Prosobranchia. Gastropod taxonomy is a dynamic and constantly evolving effort. Mild detorsion occurs in the maturation process of some species in later developmental stages, but all gastropods contain moderate degrees of nonsymmetry. The digestive tract of a typical gastropod consists of a muscular buccal mass found usually on a snout or proboscis that can be either completely or partly retracted into the cuticular lined, buccal cavity. The open circulatory system in gastropods consists of a heart with one ventricle that lies in a pericardial sac. Turbellaria infections of gastropods have been reported in Hermissenda crassicornis held in aquaria. Ultrasonography is a useful imaging modality in larger, sedated gastropod specimens. Magnetic resonance imaging has proven to be a most useful, noninvasive diagnostic technique for gastropods in research.