ARROW WORMS

Arrow worms or bristlemouth worms
Slender, tiny and transparent, the planktonic arrow worms present viewing problems even though they may be extremely abundant when in “bloom.” Each species possesses a pair of lateral fins and a tail fin, but the worms swim by repetitive flexing of the central body area. This distinctive motion is an eye-catching hint of its presence. The most obvious anatomical feature of an arrow worm is a formidable pair of bristle-bearing “jaws” adjacent to its mouth.
Eighteen species of arrow worms are found in the marine waters of the Pacific Northwest.