Corals are animals in which phylum?

Corals are animals in the phylum Cnidaria.

Cnidaria is an aquatic animal phylum that includes corals, sea anemones, jellyfish and hydroids. Its members are defined in part by cnidocytes, specialized stinging cells used to capture prey and deter predators. Most cnidarians have radial symmetry and a simple body plan centered on a single opening.

Corals belong to the class Anthozoa, alongside sea anemones. Reef-building stony corals are colonies of tiny individual animals called polyps. Each polyp secretes a calcium-carbonate skeleton, and repeated growth over generations can produce large reef structures.

A long-standing misconception treated corals as plants because they remain attached to the seabed and may host photosynthetic algae. They are animals, however, and many coral colonies gain energy from symbiotic algae living in their tissues. Porifera refers to sponges, Mollusca to animals such as clams and octopuses, and Echinodermata to starfish and sea urchins.