Animals that possess body cavities but ones that are not completely surrounded by mesodermal tissue.

Instead, in pseudocoelomates body cavities are bound by mesodermal tissue on only one side, with endodermal tissue found on the other. Roundworms (phylum Nematoda) are pseudocoelomates as too are rotifers (phylum Rotifera).

See also acoelomate as well as coelomates.