Definition of mesozoan in English:



  • A minute worm which is an internal parasite of marine invertebrates. It lacks any internal organs other than reproductive cells, and dissolved nutrients are absorbed directly from the host's tissues.

    • ‘The dicyemid mesozoans, once hypothesized to be non-bilaterian metazoans, have since been shown to possess central class Hox genes indicating that these enigmatic parasites are secondarily simplified bilaterians.’
    • ‘The major group of mesozoans, the Dicyemida, live as microscopic parasites in the renal organs of squid and octopuses.’
    • ‘D. briarei is the only species of mesozoan reported from Octopus briareus and the third from the coast of Florida.’
    • ‘Hox evidence has also placed dicyemid mesozoans in the clade.’
    • ‘The dicyemid mesozoans are obligate parasites that inhabit the cephalopod renal appendage.’


Early 20th century: from modern Latin Mesozoa (from mesos ‘intermediate’ + zōion ‘animal’) + -an.