Western brown snake
| Western brown snake | ||||||||||||
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Western brown snake ( Pseudonaja nuchalis ) |
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| Scientific name | ||||||||||||
| Pseudonaja nuchalis | ||||||||||||
| Günther , 1858 |
The western brown snake ( Pseudonaja nuchalis ), also western brown otter , is a species of snake from the family of poisonous snakes (Elapidae) and belongs to the genus of brown snakes ( Pseudonaja ). There are no known subspecies .
features
Pseudonaja nuchalis reaches a total length of an average of 120 cm, maximum between 180 and 200 cm. The body is slim. The head is relatively short and hardly separates from the neck. The eyes are large and have a round pupil. The body is variable in color, the top of the body can be olive green, brown or reddish. The head can be colored black. The ventral side is yellowish and has reddish or gray speckles. As is typical for venomous snakes, the venom apparatus consists of venom glands located on the side of the skull (specialized salivary glands ) and immobile fangs located in the anterior upper jaw (proteroglyphic tooth position).
Pseudonaja nuchalis can easily be confused with the eastern brown snake ( Pseudonaja textilis ).
Pholidosis
The pholidosis (scaling) shows the following characteristics:
- 6 upper lip shields ( supralabials ),
- 17 rows of smooth trunk scales ( Scuta dorsalia ),
- 180 to 230 abdominal shields ( scuta ventralia ),
- 50 to 70 paired under- tail shields ( Scuta subcaudalia ) and
- 1 split anal shield ( scutum anale ).
Systematics
The populations sometimes identified as Pseudonaja nuchalis are to be regarded as a species complex . There are at least three different types : Pseudonaja aspidorhyncha , Pseudonaja mengdeni and Pseudonaja nuchalis .
distribution
The distribution area includes areas within Australia throughout mainland Australia ( New South Wales , Northern Territory , Queensland , South Australia , Victoria , Western Australia ). The populated habitats are diverse and include hardwood forests, spinifex- covered dunes, rocky plains and arid areas inland.
Way of life
The western brown snake leads a diurnal and largely ground-dwelling way of life. In the heat of the day, especially in the northern areas of the distribution area, it shifts its activity phase to twilight and night. Animal structures, wood and the like serve as hiding places. The species is also not afraid of being close to people, such as gardens and the like. The prey spectrum includes rats, mice and lizards. Other snakes and small birds are also captured on occasion. Prey animals are grabbed with a poisonous bite, mostly entangled and held until the poisonous effect and constriction lead to the immobilization or death of the prey. The propagation is done by oviparity so oviparous. Pseudonaja nuchalis quickly flees when threatened. It is considered less aggressive than Pseudonaja textilis , but when cornered, it defends itself with poisonous bites in order to have the opportunity to escape.
Snake venom
With poison extraction (milking) from Pseudonaja nuchalis , a yield of 18 mg poison secretion (dry weight) can be achieved. The mean lethal dose is 0.473 mg / kg ( animal experiment , mouse , subcutaneous ). In 20 to 40% of bite accidents with humans, there is a significant release of poison with intoxication . There are presynaptic and postsynaptic neurotoxins and procoagulants ( prothrombin activating enzymes included).
After a poison bite in humans, mild local symptoms at the bite site and unspecific general symptoms (e.g. headache, dizziness, nausea, vomiting) can be assumed. Reports of neurotoxic symptoms with pronounced paralysis are rare; in theory, respiratory paralysis can occur. The main effects of poisoning are coagulopathy and hemorrhages . Secondary nephrotoxic and cardiotoxic effects can occur.
Measures after poison bite
A bite can occur without giving off poison (dry bite). Nevertheless, all bites of the species should first be taken seriously and medical surveillance should be carried out in any case. After a poisonous bite, a pressure bandage can be applied to the bitten limb as a first aid measure to slow the spread of toxins in the body. Those affected should not move as much as possible and should be transported to a hospital lying down. Artificial ventilation is indicated if necessary . The effect of the neurotoxins is partly irreversible. The basic therapy consists of the application of antivenin when coagulopathy or neurotoxic symptoms occur . Effective preparations are available with the preparations 'Brown Snake Antivenom' and 'Polyvalent Snake Antivenom (Australia - New Guinea)' from the manufacturer CSL Limited (Australia).
Individual evidence
- ↑ a b The Reptile Database: Pseudonaja nuchalis (accessed June 26, 2018)
- ↑ a b Australian Museum: Pseudonaja nuchalis (accessed June 26, 2018)
- ↑ a b c d University of Adelaide, Clinical Toxinology Resources: Pseudonaja nuchalis (accessed June 26, 2018)
literature
- Ludwig Trutnau: Snakes in the Terrarium Vol. 2: Poisonous snakes . Verlag Ulmer, Stuttgart 1998, ISBN 3-800-1705-23 .
