INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM EUMETAZOA

DIVISION TRIPLOBLASTICA, OR BILATERIA

SUBDIVISION SPIRALIA

It unites a vast group of invertebrate animal phyla characterized by a spiral Cleavage type of the egg Cell and a primary Mouth formed at the site of the blastopore. The subdivision includes phyla with diverse body plans and Levels of Organization: Flatworms, Xenoturbellida, Orthonectida, Dicyemida, Gnathostomulida, Micrognathozoa, Rotifera, Acanthocephala, Cycliophora, Entoprocta, Gastrotricha, Nemertea, Lobatocerebrida, Annelida, Pogonophora, Echiura, Sipuncula, and Mollusca. Let us examine the most important of them.



Last update: 13/08/2026

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