Parazoa

animal subkingdom

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Last updated

July 23, 2026

Quick Summary

Parazoa is a subkingdom of animals that includes sponges and placozoans. These are multicellular organisms that, unlike more complex animals (Eumetazoa), lack true tissues and organs. Their cells are specialized and coordinate their activities, but they do not form organized tissues. Sponges, the most well-known Parazoa, have a simple body plan with a system of canals for water circulation, which they use for feeding, respiration, and waste removal. This cellular level of organization has proven adaptive, allowing sponges to thrive in marine environments.1234

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Parazoa: a cellular level of organization
Although the two phyla in this subkingdom, Porifera (sponges) and Placozoa, lack clearly defined tissues and organs, their cells specialize and integrate their activities. Their simplicity has been adaptive, and sponges have remained important in benthic marine habitats since…
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Although the two phyla in this subkingdom, Porifera (sponges) and Placozoa, lack clearly defined tissues and organs, their cells specialize and integrate their activities. Their simplicity has been adaptive, and sponges have remained important in benthic marine habitats since…
Read More