The Mesozoa are minuscule, worm-like parasites of marine invertebrates. Generally, these tiny, elusive creatures consist of a somatoderm (outer layer) of ciliated cells surrounding one or more reproductive cells.

mesozoan, any of approximately 50 species of small, ciliated, multicellular animals that parasitize other marine invertebrates belonging to the phyla Rhombozoa and Orthonectida. These wormlike organisms lack digestive, respiratory, nervous, and excretory systems; their bodies consist of two layers of as few as 20 to 30 cells each.

May 21, 2024 · Mesozoa are tiny, simple, worm or blob-like parasites that were once thought of as intermediates between protozoa (motile single-celled organisms) and metazoa (multicellular animals). However, now they are generally thought of as degenerate metazoa, that is, metazoans that descended from more complex animals but were secondarily simplified.

These minute, ciliated, wormlike animals represent an extremely simple level of organization. All mesozoans live as parasites in marine invertebrates, and the majority of them are only 0.5 to 7 mm in length. Most are composed of only 20 to 30 cells arranged basically in two layers.

Mar 2, 2020 · The mesozoa is an obsolete taxonomic term. For a long time it was a phylum of extremely simple parasitic marine worms, however the phylum has now been divided into two separate phyla. The Dicyemida (parasites of Cephalopoda) and the Orthonectida (parasites of Annelida, Echinodermata, Mollusca and Platyhelminthes).

The following points highlight the Two main types of phyla present in Mesozoans. The types are: 1. Phylum Orthonectida 2. Phylum Rhombozoa. Mesozoans: Phyla Type # 1. Phylum Orthonectida: Features: 1. Microscopic and worm-like animals, and the body length rarely exceeds 300 µm. 2.

The phylum Mesozoa comprises a small group of parasitic animals that are related to flatworms—a widely dispersed group of free-living and parasitic organisms. Some 50 species have been identified in this phylum to date, all of which are exclusively marine in their lifestyle.

Jan 1, 2014 · Members of this phylum represent the simplest of all multicellular animals, and are characterized by tiny, wormlike, parasitic organisms having a single layer of ciliated, epithelial cells that enclose one or more reproductive cells (Stunkard, 1954; McConnaughey, 1963).

Mesozoa are endoparasites of marine invertebrates. Orthonectida live in the parenchyma of turbellarians and nemertines and in the body cavities and gonads of annelids, ophiuroids, and lamellibranchs; Dicyemida, in the kidneys of cephalopods.

A small phylum of about 50 species of parasites of marine invertebrates with complex life cycles. Mesozoa are classified with the Metazoa, but they are regarded by some observers as intermediate between unicellular and multicellular animals; others consider them a degenerate group of flatworms.