Brain Corals: No Brains, But They Can Live 900 Years

Brain corals have no brains, but they have time. These slow-growing corals can grow six feet tall and live for up to 900 years, and they often become the foundations that reefs are built on. Their most unusual feature, though, is not their shape but how closely their living parts are connected — a trait that is both their strength and their weakness.

Brain coral in the Dry Tortugas, Florida. Credit: NOAA.

Where they live

Brain corals are found in the Caribbean and in the Atlantic and Pacific Oceans. They take their name from their cerebral appearance.

A colony that works as one

Brain corals show what is known as Meandroid tissue integration. The basic living units of a coral are its polyps, and in brain corals the polyps are highly associated with one another: their tissues are more closely connected than in other corals, with no skeletal structures separating them. Many researchers think that the more integrated a coral's polyp tissue is, the more advanced the species.

The advantage is sharing. Connected polyps can pass molecules such as nutrients, hormones and oxygen between them, which makes it easier for the colony to communicate.

The weakness in the same design

The connection that helps a colony also exposes it. If even one polyp falls ill, a pathogen can spread quickly to the rest of the colony. Some species of brain coral have suffered mass die-offs from diseases such as black band disease and white plague, and from thermal bleaching.

Sources

Based on "What are brain corals?" from NOAA's National Ocean Service, a work of the United States government in the public domain.