Photo of an aquatic isopod in an aquarium, crawling on a rock.

    Aquatic Pillbugs and Sowbugs (Aquatic Isopods)

    Freshwater members of the crustacean order Isopoda
    Photo of a freshwater jellyfish

    Freshwater Jellyfish

    Craspedacusta sowerbii (syn. C. sowerbyi)
    Photo of several prosobranch pond snails crawling on a rock.

    Gilled Aquatic Snails (Prosobranch Pond Snails)

    Over 20 Missouri species in former subclass Prosobranchia
    No photo available

    Hydras

    Various species in the genus Hydra
    Photo of amphipod on a rock

    Scuds and Sideswimmers (Amphipods)

    Species in the crustacean order Amphipoda
    Photo of a pink planarian on a rock.

    Turbellarians (Planarians; Free-Living Flatworms)

    Species in genera Dugesia, Planaria, etc.
    Zebra Mussel

    Zebra Mussel

    Dreissena polymorpha
    invasive icon

    Invasive