Geography of South America Great American Interchange. The Andes, likewise a comparatively young and seismically restless mountain range, runs down the western edge of the continent; the land to the east of the northern Andes is largely tropical rain forest, the vast Amazon River basin. The continent also contains drier regions such as eastern Patagonia and the extremely arid Atacama desert. The South American continent also includes various islands, most of which belong to countries on the continent. The Caribbean territories are grouped with North America. The South American nations that border the Caribbean Sea—including Colombia, Venezuela, Guyana, Suriname, and French Guiana—are also known
Smallest organisms 0.46 mm. The smallest land snail is "Acmella nana". Discovered in Borneo, Malaysia, and described in November 2015, it measures only 0.7 mm. The previous record was that of "Angustopila dominikae" from China, which was reported in September 2015. This snail measures 0.86 mm. The smallest crustacean, and indeed the smallest arthropod, is the tantulocarid "Stygotantulus stocki", at a length of only . Eriophyid mites measure 125 to 250 μm in length. Adult males of the parasitic wasp "Dicopomorpha echmepterygis" can be as small as 139 μm long, smaller than some species of protozoa (single-cell creatures); females are 40% larger.