Unique Biodiversity A brief overview of the natural history of the UK Overseas Territories and Crown Dependencies 1,500 endemic species are found in the UK Overseas Territories compared to around 90 endemic species in the UK. Therefore, it has been said that they have 94% of known endemic species for which the UK is responsible under international conventions. Far less is know about the unique invertebrate fauna than in mainland UK. That said, St Helena has 460 endemic invertebrate species many are critically endangered. Montserrat has over 1,200 invertebrate species, of which 718 species are beetles and 81 species are single-island endemics. The waters around the Falkland Islands are nutrient rich attracting 25 species of marine mammals, including whales, porpoises and dolphins. The Cayman Islands has 25 species of amphibians and reptiles, of these 17, some with multiple subspecies are endemic. Two sub-species of rock iguana, the Grand Cayman blue iguana and the Cayman Brac rock iguana, are subjects of a conservation programme. The British Indian Ocean Territory contains the Great Chagos Bank, one of the world’s largest and richest atolls. Over 300 species of corals and 'reef building relatives' have been documented within its reefs. At least 180 endemic plant species are found in the UKOTs. St Helena has 49 including: olive, rosewood and ebony trees which are some of the rarest. UKOTs Online Herbarium was established by Royal Botanic Gardens, Kew in partnership with organisations in the UKOTs. The green turtle Chelonia mydas nests in many of the Overseas Territories: Anguilla, Ascension Island, the BIOT, the British Virgin Islands, the Cayman Islands, Henderson Island (Pitcairn), Montserrat and the Turks and Caicos Islands. Alderney, part of the Baliwick of Guernsey, has one of the greatest tidal ranges in Europe at 20ft. Over 100 species of marine algae have been identified in its waters.