← Glossary · 🐠 Corals
Polyp
A polyp is the individual coral animal — a small sac with a mouth ringed by tentacles; what we call "a coral" is usually a colony of many connected polyps.
Whether polyps are extended or retracted is one of the clearest signs of a coral's mood — happy corals open up to feed and photosynthesise. Polyps staying shut can mean too much flow or light, or unstable water.