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.
Phyla Orthonectida and Rhombozoa; formerly placed together in the phylum Mesozoa, which was thought to be intermediate between protozoans and metazoans‘The major group of mesozoans, the Dicyemida, live as microscopic parasites in the renal organs of squid and octopuses.’
- ‘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.’
- ‘Hox evidence has also placed dicyemid mesozoans in the clade.’
- ‘The dicyemid mesozoans are obligate parasites that inhabit the cephalopod renal appendage.’
- ‘D. briarei is the only species of mesozoan reported from Octopus briareus and the third from the coast of Florida.’
Early 20th century from modern Latin Mesozoa (from mesos ‘intermediate’ + zōion ‘animal’) + -an.