More than 1 600 different species of fish live in the Great Barrier Reef, about double the 747 species of fish found in the Mediterranean Sea. It also contains 136 species of sharks and rays, whereas just 34 species of sharks have been recorded off the entire Pacific coast of North America. It is home to 25 marine species threatened with extinction, including six species of marine turtles. The reef also supports more than 30 species of marine mammals. One-third of all soft coral varieties can be found there, along with 411 kinds of hard coral.