Which phylum is NOT a coelomate?

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Multiple Choice

Which phylum is NOT a coelomate?

Explanation:
A true coelom is a body cavity fully lined by mesoderm, forming within the embryo and providing a dedicated space for organs. Nematodes have a pseudocoel, a fluid-filled cavity that lies between endoderm and mesoderm and is not completely lined by mesoderm, so they do not have a true coelom. The other listed phyla develop and maintain a true coelom, with the cavity lined on both sides by mesoderm and organs suspended within it. This makes nematodes the ones that are not coelomate, as their body plan uses a pseudocoel rather than a true coelom.

A true coelom is a body cavity fully lined by mesoderm, forming within the embryo and providing a dedicated space for organs. Nematodes have a pseudocoel, a fluid-filled cavity that lies between endoderm and mesoderm and is not completely lined by mesoderm, so they do not have a true coelom. The other listed phyla develop and maintain a true coelom, with the cavity lined on both sides by mesoderm and organs suspended within it. This makes nematodes the ones that are not coelomate, as their body plan uses a pseudocoel rather than a true coelom.

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