ARROWWORM

arrowworm, chaetognath

(noun) 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

Source: WordNet® 3.1

Etymology

Noun

arrowworm (plural arrowworms)

(zoology) A transparent marine worm of the phylum Chaetognatha, found in plankton.

Source: Wiktionary

Ar"row*worm`, n. (Zoöl.)

Definition: A peculiar transparent worm of the genus Sagitta, living at the surface of the sea. See Sagitta.

Source: Webster’s Unabridged Dictionary 1913 Edition