Cobras are among the best-known and most feared of the world's venomous snakes, iconic for their fierce gaze and ominous neck-hoods, which are often beautifully patterned. While many species are inhabitants of dry country -- broken scrub, open woodland and even desert -- a few species make their homes in moist tropical rainforests.
Cobras inhabiting rainforest environments are found in the tropics of Africa, Asia and Indonesia, from the riverine swamps of the Congo Basin to the highland selva (or rainforest) of the Western Ghats in India. Some rainforest cobras are specialised for such habitats, while others, like the wide-ranging Indian cobra, are generalists in their preferences and also utilise more open country.
Certain rainforest cobras are mostly arboreal -- that is, they spend much of their time above ground in trees. In equatorial Africa, the Gold's and black tree cobras share space with another, unrelated climber, the forest cobra. The latter species, which reaches lengths in excess of 8 feet, is the longest cobra in Africa, and isn't restricted to rainforest; it may also prowl savannahs and open woodlands. The banded water cobra of Central and East Africa is, by contrast, an aquatic serpent, foraging deftly underwater. The king cobra of southern and southeastern Asia, meanwhile, freely travels between the arboreal, terrestrial and aquatic worlds. Another tropical African species, the burrowing cobra, is little-known but thought to either haunt subterranean tunnels, as its name suggests, or simply the duff layer of the rainforest floor.
Possessed of strong venom and sometimes impressive size, cobras can be formidable predators. Most striking is the king cobra, which holds the title of longest venomous snake in the world: Exceptional specimens may exceed 18 feet in length. Among the specialities of this massive cobra is snake-eating: in many areas, its fellow serpents are its most important prey -- including relatively large pythons. Banded water cobras snatch fish underwater. Most species of rainforest cobra, like other venomous snakes, will hunt any small animal they can envenomate, including rodents and birds.
Cobras and other elapid snakes usually possess neurotoxic venom affecting the function of the nervous system, which makes them potentially very dangerous if provoked to bite. The venom of the king cobra can induce cardiac arrest and respiratory failure; while other venomous snakes may be more potent, the king cobra is notorious on account of its great size, which allows for the delivery of a large amount of venom in a single bite. Indeed, the bite of a large king cobra is lethal enough to fell 20 human beings or a full-grown elephant, according to National Geographic.