Coral is a common name for several species in the phylum
, which is a major group of invertebrate
animals. Corals have stony skeletons
. The skeleton provides a substratum to support the living organism
, or polyp
, and serves as a protective enclosure where a polyp might hide if threatened. Corals can be white, orange, red, green, yellow, blue, or purple.
Corals usually feed at night on plankton and other
microorganisms. They capture them with nematocysts, which are poison cells released from cells on their tentacles. They also have cilia around their mouths to aid in catching suspended food. Many tropical corals get energy from algae that live within their tissue and give the endodermal cells a yellow or brown color.
Coral polyps have many predators including parrotfishes,
butterflyfishes, and sea stars.
Some of the things that coral can be made into are: limestone materials for road building, ornaments, and jewelry.