Coral reefs are the one of earths most complex ecosystems, containing over 800 species of corals and one million animal and plant species. Here we see a shallow coral reef consisting mainly of hard corals supporting shoals of Yellowtail Barracuda (Sphyraena flavicauda). These young Barracuda remain in a shallow Lagoon schooling together underneath a boat, to hunt fish and avoid predators. This is a typical juvenile behaviour that helps to ensure the survival of the species. Several scuba divers are in the background enjoying the nature around them. Footage obtained whilst scuba diving in Ko Haa, Andaman Sea, Krabi, Thailand.