Definition of arrow worm in English:

arrow worm

noun

  • A slender transparent wormlike animal with fins, having spines on the head for grasping prey. It is common in marine plankton.

    Also called chaetognath (see Chaetognatha)
    • ‘Chaetognaths (‘arrow worms’) were considered to be deuterostomes until quite recently, when they were relocated to the protostomes.’
    • ‘Chaetognaths (commonly named arrow worms) are transparent marine metazoans, ranging in size from 2 to 120 mm.’
    • ‘As mentioned, the chaetognaths (‘arrow worms’) are clearly orthodox bilaterians.’
    • ‘Early Cambrian ‘protoconodonts’ are currently believed to be the unrelated remains of chaetognaths (or ‘arrow worms’).’
    • ‘Chaetognaths, commonly called arrow worms, were considered deuterostomes based on their tripartite coelom and the retention of the blastopore to form the anus.’