In 2008, Tom Mullikin led his team on a scientific expedition to the Great Barrier Reef of Australia. Mullikin’s team completed dives off the reef to study coral "bleaching" and to familiarize themselves with one of the richest and most diverse marine biospheres in the world. The Great Barrier Reef is the world's largest reef system and is composed of over 2,900 individual reef and it has over 900 islands stretching for over 2,600 kilometers. This reef is home to more than 1,500 fish species and at least 330 species of ascidians on the reef system. During the expedition, Mullikin’s team studied this diverse wildlife. In the reef there have been thirty species of whales, dolphins, and porpoises that have been recorded in the Great Barrier Reef, six species of sea turtles that visit the reef in order to breed and 215 species of birds (including 22 species of seabirds and 32 species of shorebirds) visit the reef or nest on the islands.