\Wa"ter mite`\ (Zo["o]l.)
Any of numerous species of aquatic mites belonging to
{Hydrachna} and allied genera of the family {Hydrachnid[ae]},
usually having the legs fringed and adapted for swimming.
They are often red or red and black in color, and while young
are parasites of fresh-water insects and mussels. Called also
{water tick}, and {water spider}.