Overview

Stony coral is a term for over 180 different species of hard coral that grow in warm, shallow ocean waters all over the globe. The coral forests in the coastal reefs surrounding Amami-Oshima are formed by species of this coral. Coral is made up of individual polyps, each about 2 millimeters wide, that build colonies of calcium-carbonate skeletons as they grow.

Stony corals are among the fastest-growing corals, with some species expanding by 20 to 30 centimeters a year. The polyps extend from their skeletons to feed on plankton and other organic matter in the sea and pull back when disturbed. These corals are mostly brown, but they can be very colorful, with shades of green, blue, and purple. They grow in many short branches on a flat base in a shape called “table coral,” and as longer vertical extensions called “branch coral.” In early summer, divers can experience the coral’s spawning as the polyps release bundles of sperm and eggs that burst on the surface of the sea, then drift down to the seabed like a heavy snowfall. The spaces among their branches are a habitat and refuge for other marine life, including fish and invertebrates. They are adversely affected by changes in the environment: some two decades ago Amami-Oshima’s corals suffered from bleaching, but have now recovered.

An experienced guide takes you to the proper beaches or spots for snorkeling and diving