$(i)$ Draw a neat diagram of Hydra.
$(ii)$ Label mesoglea and gastrovascular cavity.
$(iii)$ Name the group of animals it belongs to.
$(iv)$ Name one species of this group that lives in colonies.

(N/A) $(i)$ and $(ii)$ The diagram of Hydra with the required labels is provided in the reference image.
$(iii)$ Hydra belongs to the phylum Coelenterata,also known as Cnidaria.
$(iv)$ Corals are a well-known example of animals in this group that live in colonies.