water spider

Water mite \Wa"ter mite`\ (Zool.)
   Any of numerous species of aquatic mites belonging to
   {Hydrachna} and allied genera of the family {Hydrachnidae},
   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}.
   [1913 Webster]
   [1913 Webster]
    

Water spider \Wa"ter spi"der\ (Zool.)
   (a) An aquatic European spider ({Argyoneta aquatica}) which
       constructs its web beneath the surface of the water on
       water plants. It lives in a bell-shaped structure of
       silk, open beneath like a diving bell, and filled with
       air which the spider carries down in the form of small
       bubbles attached one at a time to the spinnerets and hind
       feet. Called also {diving spider}.
   (b) A water mite.
   (c) Any spider that habitually lives on or about the water,
       especially the large American species ({Dolomedes
       lanceolatus}) which runs rapidly on the surface of water;
       -- called also {raft spider}.
       [1913 Webster]