Sea turtles are characterized by a large, streamlined shell (carapace), and non-retractable head and flippers. In all species except the leatherback, the body is covered with hard, keritinized plates called "scutes". The number and arrangement of scutes on the carapace and head are used to identify between the species. Their colors range from pale green to almost black. Jaw shape reflects adaptation to its diet, thus varies between different species.
Of the seven species of sea turtles now existing in the world, 5 are found in Taiwan waters. These are green turtle, loggerhead, hawksbill, olive ridley and leatherbacks. Among these species, the green turtle is the most abundant and the only species that is still nesting in islands of Taiwan these days.