There are over 80 types of mangrove treesin the world. Mangroves are often recognized by their complex prop root systems which allow them to live in the intertidal zone along tropical coastlines. Mangroves help build coastline, since they slow the movement of water which allows for sediment buildup. They also serve as a buffer against storm surges, resulting in lessened flood damage from hurricanes.
Read more about these amazing trees on Wikipedia