For example, only about 4.3% of the total fish species in the Red Sea have actually invaded the Mediterranean. There are many hypothesis that attempt to explain the asymmetry and general processes involved in biotic interchange:   During the Trans-Arctic Interchange (, Early Pliocene) sea levels rose, submerging the Bering Strait, and allowing marine organisms from the North Pacific and North Atlantic/Arctic Ocean to come into contact with each other. During the Great American Interchange (, Pliocene) tectonic forces pushed North and South America together, allowing for the formation of the Panamanian land bridge linking the two continents together. This event has been extensively studied. The Indian Subcontinent and Mainland Asia Interchange (Eocene) was the collision of the Indian Plate with mainland Asia allowing for biotic interchange mainly from mainland Asia onto the Indian subcontinent. Bering Land Bridge Interchange (late Cenozoic) was an interchange between Asian and North American land species across the Bering land bridge. The African and Eurasian Interchange (, early Miocene) occurred between Africa and Eurasia through the Middle East after the Tethys sea closed. The Trans-Suez Interchange is a human-induced biotic interchange between the Mediterranean and the Red Sea due to the construction of the Suez canal. Another human-induced biotic interchange, the Japan–North American Interchange, is between marine species off the coast of Japan and North America. These species are transported as larvae in ships' ballast. The Panama Canal Interchange between the eastern Pacific and western Atlantic oceans through the Panama Canal. This interchange has been relatively minimal due to the canal containing freshwater.