South Asian river dolphin The sphincter-like structure is capable of sensing light, and may be able to sense the direction from where the light was emitted. However, the muddy waters, or low light conditions, that the "Platanista gangetica" inhabit negate the use of the little vision that remains. The Ganges subspecies shows object-avoidance behavior in both the consistently heavily murky waters of its habitat and in clear water in captivity, suggesting that it is capable of using echolocation effectively to navigate and forage for prey. However, there is limited information on how extensively vocalization is utilized between individuals. This subspecies of river dolphin is
St. Pierre Island of "Casuarina equisetifolia" trees up 12 m (40 ft) high on its northwestern part, covering a third of the land area. The trees were originally planted as windbreak for the mining camp, and have unexpectedly thrived and spread. Most of the plant species once found on St Pierre are now gone, including the "Pisonia", Suicide Tree ("Cerbera odollam") and rosemallow ("Hibiscus tiliaceus"). Some "Pemphis acidula" might persist. By about 1960, it was noted that the most common herbaceous plant was "Stachytarpheta indica", while the introduced Indian Blanketflower ("Gaillardia pulchella") had established itself widely. Sisal ("Agave sisalana"), Chinese tiolet ("Asystasia gangetica"),