tardigrada

from WordNet (r) 3.0 (2006)

Tardigrada
    n 1: in some classifications considered a separate phylum:
         microscopic arachnid-like invertebrates living in water or
         damp moss having 4 pairs of legs and instead of a mouth a
         pair of stylets or needlelike piercing organs connected
         with the pharynx [syn: {Tardigrada}, {class Tardigrada}]

from The Collaborative International Dictionary of English v.0.48

Tardigrada \Tar`di*gra"da\, n. pl. [NL. See {Tardigrade}, a.]
   1. (Zool.) A tribe of edentates comprising the sloths. They
      are noted for the slowness of their movements when on the
      ground. See {Sloth}, 3.
      [1913 Webster]

   2. (Zool.) An order of minute aquatic arachnids; -- called
      also {bear animalcules}, {sloth animalcules}, and {water
      bears}.
      [1913 Webster]