Tuvalu consists of nine separate islands: six atolls and three reef islands. An atoll typically consists of several islets: Tuvalu has a total of 124 islands and islets. Each island is surrounded by a coral reef. Tuvalu's small, widely scattered atolls have poor soil and a total land area of only about making Tuvalu the fourth-smallest country in the world. The sea level at the Funafuti tide gauge has been rising at a rate of 3.9 mm per year, and it has been determined that rising sea levels are causing more wave energy to be transferred across reef surfaces, which has tended to push more sand onto island shorelines, increasing islands’ land area. Over a recent four-decade period, there was a net increase in the land area of the islets of 2.9% (73.5 ha), although the changes were not uniform: About 74% of them increased in size and about 27% decreased in size. Islands of Tuvalu The islands of Tuvalu are spread out between the latitude of 5° to 10° south and longitude of 176° to 180°, west of the International Date Line. The name, Tuvalu, means "eight standing together" in Tuvaluan. The Coral reefs of Tuvalu consists of three reef islands and six atolls, containing approximately of reef platforms. The reef islands have a different structure to the atolls, and are perhaps better described as “reef platforms,” as they are small, tabular platforms that lack the salt-water lagoon typically found on reef islands. The reef platforms do have a completely enclosed rim of dry land, and the rim surrounds the remnants of a lagoon, but these lagoon remnants have no connection to the open sea, and tend to dry up as coral debris accumulates in them over time. For example, Niutao has two brackish, saline lakes which are the degraded remnants of an ancient lagoon. The smallest island, Niulakita, which is the ninth island in the Tuvaluan archipelago, has not been continuously inhabited. It has been privately owned since 1944, when the Gilbert and Ellice Islands Colony administration purchased the island and granted people from Vaitupu permission to settle there. However, in 1949, a successor administration made the controversial decision to expel the Vaitupuans from Niulakita, and arrange for residents of Niutao to settle there instead, because Niutao was felt to be overpopulated. Niulakita is a separate local government district, but it is administered as part of Niutao, and