Photo of a spothanded crayfish viewed from above on white background.

    Crayfishes

    About 36 species in Missouri
    Monkey Face Mussel

    Freshwater Mussels

    Bivalve molluscs in order Unionoida
    Photo of a leech

    Leeches

    Various species in the subclass Hirudinea
    image of Narceus Millipede crawling across gravel

    Millipedes

    More than 900 species in North America north of Mexico