Try diving on Koh Tao to see really small and beautiful fish like Seahorse. Seahorses are tiny fishes that are named for the shape of their head, which looks like the head of a tiny horse. There are at least 25 species of seahorses. You can find one of them on the dive site Mango Bay on the north of Koh Tao Island. Seahorses use their dorsal fins (back fins) to propel slowly forward. To move up and down, seahorses adjust the volume of air in their swim bladders, which is an air pocket inside their bodies. Tiny, spiny plates cover seahorses' bodies all the way down to their curled, flexible tails. The tail can grasp objects, helpful when seahorses want to anchor themselves to vegetation.