Question

Does coelenterates have body cavities?

Answer 1

Hint: Coelenterates are diploblastic animals. Hence, they lack a coelom. The coelom is a fluid-filled body cavity lined by mesoderm. Instead, they have a gastrovascular cavity. This cavity is filled with undifferentiated cells, which are called meso glial cells.

Complete answer:
Coelenterates have an open body cavity called the gastrovascular cavity. It is not a true cavity. The space present between the body wall and the gut wall is called ‘body cavity.’ A body cavity lined by mesoderm is called ‘coelom’. Animals that possess coelom are called ‘coelomates’. Examples of coelomates are annelids, echinoderms, molluscs, arthropods, hemichordates, and chordates.
Now let's study in detail.
Coelenterates are a term used around the Phylum Cnidaria and Ctenophora. Their name comes from the Greek word ‘koilos’ meaning hollow and ‘enteron’ meaning intestine. As the name suggests, coelenterates are animals with a hollow body cavity. It is a common feature for both the phyla. However, the body cavity is not fluid-filled and is not lined by mesoderm. Hence they lack a coelom. The body has a single opening called hypostome. This opening is surrounded by sensory tentacles. The function of sensory tentacles is to capture mostly planktonic prey. These sensory tentacles are surrounded by a spacious cavity called the gastrovascular cavity or ‘coelenteron.’ It is not a true body cavity.

So, the correct answer is, Coelenterates have an ‘open or hollow body cavity’. It is not a true body cavity.

Note: -Hydra, sea anemones, jellyfish, and obelia come under the phylum Cnidaria.
-A body cavity not entirely lined by mesoderm is called ‘pseudocoelom’ and the animals showing that are called ‘pseudocoelomates.’ An example of this kind is aschelminthes.
-Acoelomates are animals in which the body cavity is absent, e.g., Platyhelminthes.
-Functions of the gastrovascular cavity in coelenterates are extracellular digestion and nutrient transport.