No a Hydra is non a pseudocoelmate, acoelomate, or eucoelomate. The basic body plan is a sac with central digestive compartment, the gastrovascular cavity. A single opening functions as mouth and anus. There are 2 variations on this body plan: the sessile polyp and the motile medusa
A Planarian is an acoelomate, meaning they do not have a body cavity at all.
Acoelomate animals, like flatworms
Acoelomate
Flatworms
Molluscs are acoelomate; they have no body cavities.
coelomate
tapeworm.
Acoelomate
Acoelomate is an animal that lacks a body cavity or a coleom.
The acoelomate phyla are Platyhelminthes (flatworms) and Nemertea (ribbon worms). These animals lack a true body cavity (coelom) between their digestive tract and body wall. Acoelomates rely on other means, like a simple body plan and mesenchyme tissue, for support and structure.
The type of body plan a Dugesia has is an acoelomate body. This elongated body lacks internal structures for holding internal organs.
A Hydra Meaning Those Three Headed Crocodile-Like Dragon?!