Question

Body cavity of Hydra/coelenterata is known as
a. Coelenteron
b. Pseudocoel
c. Enterocoel
d. Haemocoel

Answer 1

Hint: Phylum coelenterata also known as cnidaria includes hydra. Corals, sea anemones and jellyfish are some examples of hydras. Hydras have body cavity as its gut and have a single opening which can be called by sphincter. The body cavity is called a coelenteron. Different types of animals classified according to their body cavities.

Complete answer:
Hydras are typical because they do not have a medusa stage as a part of their life cycle as do most other coelenterates. Hydras are found in freshwater, ponds, lakes, and streams. They live and reproduce sexually and asexually. They have four types of nematocytes on their tentacles which perform various types of functions.

> Option A: Coelenteron or coelenterata comes from the ancient greek word which means hollow body cavity. Coelenterate lacks a specialized circulatory system. Hydra have coelenterate radially symmetric body plan of two cell layers without a true body gut, having instead a gastrovascular cavity, with the mouth as a single opening.

> Option B: Pseudocoels body cavity is not derived from the mesoderm, as in a true coelom. Pseudo means false their body fluids bath the organs and receive their nutrients from fluid in the cavity.

> Option C: Enterocoel body cavity is derived from the walls of the archenteron. It is present in some invertebrates.

> Option D: Haemocoel type of body cavity contains circulatory fluid. It is found in invertebrates where hemolymph circulates through it. It contains blood or hemolymph and functions as a part of the circulatory system.

As discussed above we have reached the conclusion that the body cavity of hydra is known as coelenteron.
Hence, the correct answer is option (A).

Additional information:
Body cavity of organisms is different as it is developed from different types of walls. The coelom is the large cavity lined by mesothelium in some amniotes and invertebrates, an epithelium derived from mesoderm. Development of organs inside the coelom is independent of the body walls. Peritoneum is the fluid present in it which cushions and protects them from shocks.

Note: Arthropods and most molluscs have a reduced coelom but they have true coelom. Haemocoel is the principal body cavity of an open circulatory system, often derived from the blastocoel.