What is coral?
Corals are actually animals! Each coral individual is comprised of a polyp with a mouth and stomach. The polyp tentacles have stinging cells called nematocysts which help the coral catch food like plankton. Most corals are colonies made up of many individual polyps.
Most corals have a clear tissue with millions of zooxanthellae, colored algae cells, that live in the tissue and get most of their energy from the sunlight. The zooxanthellae help feed the coral with sugars they produce. Corals live in a symbiotic relationship with zooxanthellae, they cannot survive without them.
What types of corals are there?
Most corals fall into 3 categories:
1. Soft corals: They do NOT have a stony skeleton. Examples are zoas, mushrooms, leather corals
2. Large polyp stony corals (LPS): May be seen as larger, individual polyps or in a colony. Examples are lobos, acans, torch and hammer corals
3. Small polyp stony corals (SPS): These polyps are so small, they're almost always seen as a colony. Examples are acros, montis, birds nest corals.