Adductor muscle: Large muscle that bivalve mollusks possess which are attached to both valves of the shell and when contracted tightly close the shell.Bivalve: A mollusk whose body is enclosed by a pair of hard shells.Conglutinate: A mass of glochidia held together by mucous. These often look very similar to aquatic insects or worms.Endangered: The species is threatened with extinction throughout all or a significant portion of its range.Excurrent Siphon: An opening that expels the water cleaned of food and oxygen away from the mussels body.Exotic Species: A species of animal or plant that has been introduced to an area outside of its native habitat.Extirpated: The species is no longer found in this portion of its historic range.Foot: Muscular organ that a bivalve mollusk uses for locomotion.Glochidia: The bivalved larva of freshwater unionid mussels which are parasitic on fish.Gravid: pregnant, carrying eggsHinge: the elastic part of the shell that unites the valves along the dorsal margin of the shellIncurrent Siphon: An opening that brings the oxygen and food containing water into the mussels body.Larva: Immature form of an animal.Mantle: A thin tissue that surrounds the soft body of a mollusk. In most mollusks the mantle secretes a hard protective shell.Mollusk: Soft bodied animal that posses a head, food, and a mantle.Special Concern: The species is not endangered or threatened, although it is extremely uncommon, or has unique or highly specific habitat requirements and deserves careful monitoring of its status.Threatened: The species is likely to become endangered within the foreseeable future throughout all or a significant portion of its range.Valve: one of the two halves of the shell.