There are over 175,000 islands on Earth, from tropical paradises in the warm blue waters of the Caribbean Sea to isolated rocks in the freezing Southern Ocean. Islands are well known for their high levels of biodiversity as well as being home to unique and unusual species, many of which are endemic to a single location and are found nowhere else on Earth. This species richness was the inspiration behind our new islands feature page, which aims to highlight the importance of islands and the conservation work being done to protect them.
Formed from continental fragments or the exposed peaks of oceanic volcanoes, islands vary greatly in size, climate and landscape. Islands and their surrounding waters account for around a sixth of the world’s total area, and estimates suggest that they support 20 percent of all species of birds, reptiles and plants, as well as 50 percent of the world’s marine biodiversity.
Species such as the lemurs of Madagascar and the solenodons of Cuba and Hispaniola are unlike species found anywhere else in the world. Madagascar alone has over 8,000 endemic species, and in Hawaii over 90 percent of the species are endemic.
Having evolved in isolation over thousands of years, island species are not only very different from their mainland ancestors, they are also very vulnerable to the impact of invasive species. They often lack the adaptations necessary to avoid predation or cope with competition for resources, and over the past 400 years, around half of all animal extinctions have occurred on islands. Fortunately, many conservation organisations work tirelessly to protect island species and habitats, with some standout success stories.
Claire Lamb, ARKive Researcher