Marine Life
Maine vertebrates | Marine invertebrates | Marine life brochure
Marine vertebrates
Mammals
Spinner dolphins (frequently) and common dolphins (occasionally) are seen in inshore waters. Whaleshark sightings occur regularly from November to March each year.
Reptiles
Small numbers of green and hawksbill turtles nest on Dolly and Greta beaches. Undetermined species of sea snakes occur round the Island, with the only species recorded being the pelagic yellow-bellied seasnake (Pelamis platurus).
Fish
Some 575 species of fish have been identified from the Island's waters. The faunal composition is typical of Indo-Pacific islands with nearly 68% of species widespread in the Pacific and Indian Oceans. Altogether, the fish fauna is more closely allied to the West Pacific province of the Indo-West Pacific faunal region than to the East Indian Ocean region. As is the case with most Indo-Pacific islands the rate of endemism is low and only three species, the pygmy angel fish and two undescribed pseudochromids, are apparently endemic to Christmas and the Cocos (Keeling) Islands.
Marine Invertebrates
A total of 88 species of reef building corals were collected around the Island during a survey in 1987, although it is believed that some species were overlooked. There is considered to be a low coral species diversity and this is attributed to the small size of the Island, its isolation from sources of planktonic coral larvae, and the limited range of marine habitats present.
Extensive die-off of corals took place around the Island in the early 1980s, and this may have resulted in severe depletion or local extinction of some species. In 1998 there was a widespread coral bleaching event in the Pacific and Indian Oceans and South China Sea. This event may have been triggered by the El Nino weather pattern. Large areas of the Christmas Island fringing reef were affected.
Parks Australia maintain moorings within the National Park which are used by divers and recreational fishermen. These moorings help prevent damage to coral from boat anchors.
The most abundant octocoral on the reefs around the Island is blue coral. Gorgons and antipatharians are found in the deeper slopes. Five species of clownfish sea anemones are recorded. Numerous sponges, including endemic species and varieties, have been found around the Island.
The crustacean fauna reflects the dominance of coral and coral rubble habitats with relatively small areas of sand substrate and the minimal occurrence of mud and fine silts.