Mamba

Mambas, of the genus Dendroaspis (literally "tree snake"), are fast-moving land-dwelling snakes of Africa. They belong to the family of Elapidae which includes cobras, coral snakes, death adders, kraits and, debatably, sea snakes (although sea snakes are now classed as Hydrophiidae). Mambas are feared among their habitats. In Africa, there are many legends and stories describing these snakes.

Species and subspecies
There are four species plus a number of subspecies of mamba.


 * Dendroaspis angusticeps Eastern green mamba
 * Dendroaspis jamesoni Jameson's mamba
 * Dendroaspis jamesoni jamesoni Jameson's green mamba
 * Dendroaspis jamesoni kaimosea Jameson's black-tail mamba
 * Dendroaspis polylepis Black mamba
 * Dendroaspis viridis Western green mamba

Behavior
Most of the members of this genus (for example green mambas) are arboreal. However, the black mamba is terrestrial. They are diurnal: during the day, they actively hunt their prey of small mammals, birds, and lizards, and return to the same lair nightly.

Mambas are related to the cobras (Elapidae); their threat display, when they stretch a slightly smaller 'hood' while gaping their mouth, is similar.

Many people believe that the black mamba will chase and attack humans. However, this is a myth that is probably misunderstood by the speed with which this species can move. The black mamba usually uses its speed to escape from threats. Humans are actually their predators, rather than their prey; mambas generally avoid contact with humans.

Venom
Mambas have highly toxic venom which consists mostly of neurotoxins (known as dendrotoxins). The bite can be fatal to humans without access to proper first aid and subsequent antivenom treatment, as it shuts down the lungs and heart. The Western green mamba (D. viridis) and Eastern green mamba (D. angusticeps) possess venom that has similar composition and effects as that of the black mamba, but their temperament is generally not as aggressive when provoked.

Prior to the availability of antivenom, envenomations by members of this genus carried a high fatality rate. An untreated black mamba bite has a mortality rate of a 100%. , but presently, fatalities have become much rarer due to wide availability of antivenom.

Mamba toxins
Mamba toxin (or dendrotoxin) consists of several components, with different targets. Examples are:
 * Dendrotoxin 1, which inhibits the K+ channels at the pre and post-synaptic level in the intestinal smooth muscle. It also inhibits Ca2+-sensitive K+ channels from rat skeletal muscle‚ incorporated into planar bilayers (Kd = 90 nM in 50 mM KCl). )
 * Dendrotoxin 3, which inhibits acetylcholine M4 receptors.
 * Dendrotoxin 7, which inhibits acetylcholine M1 receptors.
 * Dendrotoxin K, a selective blocker of voltage-gated potassium channels.