A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.

Video timeline: 00:00–00:05 Intro 00:06–00:13 Seahorse 00:14–00:21 Coral reef 00:22–00:28 Sea turtle 00:29–00:40 Shark 00:41–00:48 Octopus 00:49–01:00 Lion Fish 01:01–01:08 Moray 01:09–01:17 Clown Fish and Sea Anemone 01:18–01:29 Manta Ray 01:30–01:37 Red shrimp 01:38–01:48 Jelly Fish 01:49–01:58 Sea horse 01:59–02:26 Coral reef 02:27–02:38 Clown Fish and Sea Anemone 02:39–02:50 Turtle eating 02:51–03:11 Octopus 03:12–03:21 Dolphin 03:22–03:31 Sea Turtle 03:32–03:42 Star Fish 03:43–03:51 Long Arm Octopus 03:52–04:04 Scorpion Fish 04:05–04:35 Coral reef 04:36–04:58 Sea Turtle