Corals belong to which cnidarian class?

Corals belong to the cnidarian class Anthozoa.

Anthozoa includes corals, sea anemones, sea pens, sea fans and related animals. Unlike jellyfish and box jellies, anthozoans have no medusa stage; their adult form is a polyp, usually attached to the seafloor. Many corals live in colonies formed by genetically related polyps that bud from one another.

The class is divided into major living groups including Hexacorallia, which contains most stony reef-building corals, and Octocorallia, which includes soft corals and sea fans. Reef-building corals secrete calcium carbonate skeletons, allowing colonies to accumulate into reefs over many generations.

A common mix-up is to classify corals as plants because they are stationary and may resemble branching vegetation. They are animals in the phylum Cnidaria, related to jellyfish and sea anemones. Many shallow-water corals also host photosynthetic algae called zooxanthellae, which provide energy but do not change the coral’s animal classification.