The eastern green mamba is a large snake, with a slightly compressed and very slender body with a medium to long tapering tail. Adult males average around 1.8 metres (5 ft 11 in) in total length, while females average 2.0 metres (6 ft 7 in). This species rarely exceeds lengths of 2.5 metres (8 ft 2 in). In general, the total length is 4–4.3 times the length of the tail. The adult eastern green mamba has bright green upperparts—occasionally with isolated yellow scales—and a pale yellow-green belly. Sometimes they are duller-coloured before moulting. Juveniles are blue-green, becoming bright green when they are around 75 centimetres (2 ft 6 in) long. The coffin-shaped head is long and slender, with a prominent canthus which is slightly demarcated from the neck. When threatened or otherwise aroused, the eastern green mamba is capable of flattening its neck area into a slight hood. The medium-sized eyes have round pupils, the borders of which have a narrow golden or ochre edge; the irises are olive green, becoming bright green posteriorly. The inside of the mouth may be white or bluish-white.
The eastern green mamba (Dendroaspis angusticeps) is a highly venomous snake species of the mamba genus Dendroaspis native to the coastal regions of southern East Africa. Described by Scottish surgeon and zoologist Andrew Smith in 1849, it has a slender build with bright green upperparts and yellow-green underparts. The adult female averages around 2 metres (6 ft 7 in) in length, and the male is slightly smaller.
A shy and elusive species, the eastern green mamba is rarely seen. This elusiveness is usually attributed to its green colouration, which blends with its environment, and its arboreal lifestyle. It has also been observed to use “sit-and-wait” or ambush predation, like many vipers, unlike the active foraging style typical of other elapid snakes. It preys on birds, eggs, bats, and rodents such as mice, rats, and gerbils.
Its venom consists of both neurotoxins and cardiotoxins. Symptoms of envenomation include swelling of the bite site, dizziness and nausea, accompanied by difficulty breathing and swallowing, irregular heartbeat and convulsions progressing to respiratory paralysis. Bites that produce severe poisoning can be quickly fatal.
The eastern green mamba has the least toxic venom of the three green mamba species, but it is still highly venomous. Although the most commonly encountered green mamba, it generally avoids people. The peak period for bites is the species’ breeding season from September to February, during which they are most irritable.
Symptoms of envenomation by this species include pain and swelling of the bite site, which can progress to local necrosis or gangrene. Systemic effects include dizziness and nausea, difficulty breathing and swallowing, irregular heartbeat, and convulsions. Neurotoxic symptoms such as paralysis may be mild or absent. Bites that produce severe envenomation can be rapidly fatal; fatal outcomes as quickly as 30 minutes have been recorded (although the period is likely slower for Dendroaspis angusticeps).
Similarly to the venom of most other mambas, the eastern green mamba’s contains predominantly three-finger toxin agents. The exception is the black mamba, whose venom lacks the potent alpha-neurotoxin as well.
The venom of the green mamba, Dendroaspis angusticeps, was tested for effects on neuromuscular transmission and skeletal muscle contractility in isolated phrenic nerve-hemidiaphragm preparations of the rat and mouse, chick biventer cervicis muscle preparations and in aneural cultures of embryonic chick skeletal muscle.
Standard first aid treatment for any bite from a suspectedly venomous snake is the application of a pressure bandage, minimisation of the victim’s movement, and rapid conveyance to a hospital or clinic. Due to the neurotoxic nature of green mamba venom, an arterial tourniquet may be beneficial. Tetanus toxoid is sometimes administered, though the main treatment is the administration of the appropriate antivenom. A polyvalent antivenom produced by the South African Institute for Medical Research is used to treat eastern green mamba bites.