On land, on the upper area, there are black mangroves. In Japan, they can grow up to be 10 m high. There are special roots used to breathe sticking out of the ground around the tree. These roots that look like bent knees are called aerial roots.

Black mangroves found in AmamiOshima are said to be the northern most point for these plants. In the Red Data Book of Kagoshima, it is classified as 2nd class endangered plants.

Even in the tank, it flowers in summer and produces seeds. Seeds of mangrove plants are different from other plants. It has the ability to sprout on trees and is known as viviparous seed.