Question

Match them up based on their body cavities.

• A. Nematodes
• B. Flatworms
• C. Molluscs

Answer 1

Body cavity is the cavity present between body wall and gut wall.

• In some animals, the body cavity is not lined by mesoderm. Instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. This type of false body cavity is called a pseudocoelom, and the animals possessing it are called pseudocoelomates. Species belonging to Phylum Aschelminthes (Roundworms) exhibit this type of body cavity.
• Some animals do not have a true coelom and their cavity is filled by the mesodermal tissues. Such animals are called acoelomates. Species belonging to the Phylum Platyhelminthes or the flatworms are acoelomate.
• All vertebrates have a true coelom lined by a layer of mesoderm. Molluscs are vertebrates and so are coelomates.