COBRA

any of a number of highly venomous snakes of the family Elapidae that expand the neck ribs to form a hood. Cobras are found in warm regions of Africa, Australia, and Asia. They are favourites of snake charmers, who tease them into assuming the upreared defense posture. The snake sways in response to the movement and perhaps also to the music of the charmer, who knows how to avoid the relatively slow strike. The mongoose, famous enemy of cobras, wins by superior agility. The short fangs are always at the front of the mouth and contain a closed groove. The venom they produce in general contains neurotoxins, which act against the nervous system. Cobra bites are fatal in about 10 percent of human cases, but from certain species the rate is much higher. Cobras feed primarily on small vertebrates. They are ovoviviparous (live-bearing) or oviparous (egg-layers). The world's largest venomous snake is the king cobra, or hamadryad (species Ophiophagus hannah), found from southern China to the Philippines and Indonesia. It is often more than 3.6 m (12 feet) long; one is reported to have measured 5.6 m (18 feet). This species guards its 20 to 40 eggs, which are laid in a nest of leaves. It preys chiefly on other snakes and is known to have pursued people; however, relatively few bites are reported. Black-necked cobra (Naja nigricollis) The 1.7-metre (5.5-foot) Indian cobra (Naja naja) kills several thousand people every year, mostly because it visits houses at twilight to catch rats. It is found from Iran eastward. In India this species (thought by some authorities to be a complex of several species) has a spectacle-like mark on its exceptionally wide hood; elsewhere, the hood shows a ring or bars. Eastern populations have the openings in the fangs facing forward for spittinga condition perfected in the ringhals, or spitting cobra (Hemachatus hemachatus), of southern Africa. The black-necked cobra (Naja nigricollis; see photograph), a small form widely distributed in Africa, is also a spitter. Venom is accurately directed at the victim's eyes at distances of more than 2 m (7 feet) and may cause temporary, or even permanent, blindness unless promptly washed away. The Egyptian cobra (N. haje)probably the asp of antiquityis a dark, narrow-hooded species, about 2 m long, that ranges over much of Africa and eastward to Arabia. Its usual preys are toads and birds. In equatorial Africa there are tree cobras (genus Pseudohaje), which, with the mambas, are the only arboreal elapids.