Cnidaria

From sea anemones to jellyfish to hydra, the phylum Cnidaria contains a wide range of creatures. Previously known as Coelenterata (hollow gut), Cnidaria means “stinging cells”, referring to the painful sting that many of these creatures produce when touched. Along with defense mechanisms, Cnidarians possess two other evolutionary developments as well: digestion and the ability to move if needed.

Cnidarians possess a gastrovascular cavity and a mesoglea, as seen below:

The gastrovascular cavity is where food is stored and digested. They feed on larger prey such as crustaceans, grabbing the animal with their tentacles and depositing the food into their mouths. The mesoglea supports their squishy bodies, and a primitive nerve net allows them to move in case of a threat. Image courtesy of Life Sciences 11 Notes.