In the tropical and subtropical regions of the world, intertidal areas of coastlines are mostly made up of mangroves. They are common along coastlines between latitudes of 30° either side of the equator. They cover 60 to 70 % of the shorelines. Mangroves tolerate both salt and brackish water. They consist of shrubs and trees, which take about 20 years to mature and can reach a height of about 30m. Their root system helps them to anchor in the sand or any other soft substrate. Their roots also have adapted to take in oxygen and to secrete the salt from the water they absorb.

In the world there are 12 genera of mangroves present. In Galápagos we find the red mangrove (Rhizophora mangle), the white mangrove (Laguncularia racemosa), and the black mangrove (Avicennia nitida).

Today on the Island of Floreana we found the largest of the mangroves found in Galápagos, the black mangrove. This mangrove grows further back from the shore than the red. It has extensive breathing roots called pneumatophores which stick up straight out of the mud and provide aeration for the masses of underground roots. Excess salt is excreted through the leaves. The black mangrove is the most salt-tolerant of the mangroves. Unlike other plants, the seeds of mangroves germinate on the plant. The young plants fall into the water, float elsewhere and as soon as they hit land they will take in root.

The muddy sediment under the mangrove provides habitats for many animals like barnacles, oysters, snails and crabs. Their branches are also nesting sites for seabirds like the brown pelican and ground birds like the yellow warbler.

Today we had the opportunity to see all the species found on the Galápagos, the black mangrove (Avicennia nitida) of course being the largest.