Did snake bodies "deregionalize" during evolution, losing the morphological differences along their backbone? If so, how? Jason Head and David Polly took on the challenge of understanding how a lizard-like body evolves into a snake-like one. What about snakes, though? Like their body, their backbone isn't obviously divided into regions, though the divisions seem clear in lizards, their closest relatives. The vertebrae of the ribcage, for example, have a distinct shape and can easily be told apart from the lumbar vertebrae further along. At least one antivenom protects specifically against bites from this species: India Antiserum Africa Polyvalent.Make your way along the length of a vertebrate and it becomes pretty clear that the backbone is divided into regions. In 2003, a man in Dayton, Ohio, who was keeping a specimen as a pet, was bitten and subsequently died. In only a few detailed reports of human envenomation, massive swelling, which may lead to necrosis, had been described. In rabbits, the venom is apparently slightly more toxic than that of B. Another showed little variation in the venom potency of these snakes, whether they were milked once every two days or once every three weeks. nasicornis, Daboia russelii and Vipera aspis ). One study reported this venom has the highest intramuscular LD50 value-8.6 mg/kg-of five different viperid venoms tested ( B. The venom is supposedly slightly less toxic than those of B. In mice, the intravenous LD50 is 1.1 mg/kg. Relatively little is known about the toxicity and composition of the venom. The fangs penetrate deep into the victim and the venom flows through the hollow fangs into the wound.īecause of its restricted geographic range, few bites have been reported. When a rhino viper opens its mouth, it does not necessarily mean that the fangs will flip down into place. The snake has the ability to control the movement of its fangs. When not in use, the rhino viper's fangs are folded up into the roof of the snake's mouth. This venom attacks the circulatory system of the snake's victim, destroying tissue and blood vessels. The hemotoxic venom in rhinoceros vipers is much more dominant. Bitis nasicornis has both neurotoxic, as well as hemotoxic venom, as do most other venomous snakes. This is unlike the Gaboon viper, the largest of the vipers, which uses a considerably larger amount of venom. Small doses of the snake's primarily hemotoxic venom can be deadly. When approached, they often reveal their presence by hissing that sounds almost like a shriek it is said to be the loudest hiss of any African snake. Butterfly vipers are generally placid creatures. Holding them by the tail is not safe as it is somewhat prehensile, they can use it to fling themselves upwards and strike. They are slow-moving but capable of striking quickly, forwards, or sideways, without coiling first or giving a warning. Butterfly vipers prefer to hunt by ambush, and probably spend much of their life motionless, waiting for prey to wander by. They are sometimes found in shallow pools and have been described as powerful swimmers. This climbing behavior is aided by a partially prehensile tail. Although mainly terrestrial, they are also known to climb into trees and thickets, where they have been found up to 3 m (9.8 ft) above the ground. Their vivid coloration actually gives them excellent camouflage in the dappled light conditions of the forest floor, making them almost invisible. They hide during the day in leaf litter, in holes, around fallen trees or tangled roots of forest trees. Butterfly vipers are solitary and primarily nocturnal creatures.
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