ar·row·worm /-ˌwɝm/
  Ar·row·worm, n. Zool. A peculiar transparent worm of the genus Sagitta, living at the surface of the sea. See Sagitta.
  ◄ ►
  arrowworm
       n : any worm of the Chaetognatha; transparent marine worm with
           horizontal lateral and caudal fins and a row of movable
           curved spines at each side of the mouth [syn: chaetognath]