The Collaborative International Dictionary of English v.0.48:

Snakebird \Snake"bird`\, n. [So named from its snakelike neck.]
   (Zool.)
   1. Any one of four species of aquatic birds of the genus
      Anhinga or Plotus. They are allied to the gannets and
      cormorants, but have very long, slender, flexible necks,
      and sharp bills.
      [1913 Webster]

   Note: The American species (Anhinga anhinga syn. Plotus
         anhinga) inhabits the Southern United States and
         tropical America; -- called also darter, and water
         turkey. The Asiatic species (Anhinga melanogaster)
         is native of Southern Asia and the East Indies. Two
         other species inhabit Africa and Australia
         respectively.
         [1913 Webster]

   2. (Zool.) The wryneck.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Darter \Dart"er\, n.
   1. One who darts, or who throw darts; that which darts.
      [1913 Webster]

   2. (Zool.) The snakebird, a water bird of the genus Plotus;
      -- so called because it darts out its long, snakelike neck
      at its prey. See Snakebird.
      [1913 Webster]

   3. (Zool.) A small fresh-water etheostomoid fish. The group
      includes numerous genera and species, all of them
      American. See Etheostomoid.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Etheostomoid \E`the*os"to*moid\, a. [NL. etheostoma name of a
   genus + -oid.] (Zo["o]l.)
   Pertaining to, or like, the genus Etheostoma. -- n. Any
   fish of the genus Etheostoma and related genera, allied to
   the perches; -- also called darter. The etheostomoids are
   small and often bright-colored fishes inhabiting the fresh
   waters of North America. About seventy species are known,
   including the rare snail darter (Percina tanasi), 3
   inches long, found only in the Tennessee River and classified
   as a threatened species. See Darter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

darter
    n 1: fish-eating bird of warm inland waters having a long
         flexible neck and slender sharp-pointed bill [syn:
         snakebird, anhinga, darter]
    2: a person or other animal that moves abruptly and rapidly;
       "squirrels are darters"