Black otters
| Black otters | ||||||||||||
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Mulga snake ( Pseudechis australis ) |
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| Pseudechis | ||||||||||||
| Wagler , 1830 |
Black otters ( Pseudechis ) are a species of snakes from the family of poisonous snakes (Elapidae) common in Australia and New Guinea . The scientific name of the genus is composed of the Greek word "pseudes" for "false" and the name of the viper genus Echis , which means literally "False Echis". The species have a poison of medium effectiveness, which has a hemolytic , anticoagulant and muscle tissue-destroying (myolytic) effect. Human deaths are very rare.
features
anatomy
Black otters are large to very large poisonous snakes, the animals reach total lengths of up to 2.0 m, but according to some authors also up to 2.7 m. The animals are slim, the head is large and, at least in the adult specimens, clearly separated from the relatively slim neck. The canthus is sharp-edged. The sexes do not differ in terms of size and color.
Scaling
Like all venomous snakes, black otters have nine large, symmetrical shields on the top of their heads. The animals have two primary temporalia . The subcaudalia are completely or partially undivided. The anal shield is divided. The animals have 17-19 dorsal rows of scales in the middle of the body.
coloring
The German name "Schwarzottern", like the English name "Black Snakes", is not entirely appropriate, since only four of the currently recognized six species are monochrome black on top. The species with the largest distribution area, the Mulga snake, is variably brown, dark brown or copper-red on top, with the scales at the base usually being significantly lighter. P. colletti is light brown, dark brown or black on top and shows irregular pale red to orange-red banding on this ground.
distribution and habitat
The genus occurs in Australia and New Guinea. Four species are endemic to Australia, P. papuanus is endemic to New Guinea. The mulga snake is apparently also restricted to Australia , the population previously assigned to P. australis in New Guinea has recently been granted species status. Four of the six species have relatively small ranges; the Mulga snake, however, occurs in almost all of Australia, P. porphyriacus also has a large distribution area in eastern Australia. Black otters inhabit a wide range of habitats from tropical rainforests in the north and east to arid areas in the west of the continent.
Systematics
Six species are currently recognized:
- Mulga snake ( Pseudechis australis )
- P. butleri
- P. colletti
- P. guttatus
- Red-bellied black otter ( P. porphyriacus )
- P. papuanus
- P. weigeli : earlier than P. australis guided populations , but Maddock, Fry et al. (2016) to be seen as an independent species based on molecular biological studies
The populations in New Guinea as well as in north-eastern Australia that have so far been identified with P. australis should be given species status on the basis of molecular genetic studies; the name P. rossignolii was proposed for the population in New Guinea and the name P. pailsei for the population in northeastern Australia .
Lifestyle, Diet and Reproduction
Black otters are predominantly nocturnal and apparently exclusively ground-dwelling. As far as is known, the diet is varied and consists of a wide range of small vertebrates such as rodents , lizards, snakes and frogs. In most species, however, mammals make up less than 10% of the prey, only with P. guttatus mammals make up a significantly higher proportion with 39% of the prey. P. porphyriacus is viviparous ( viviparous ), the other types are not known to oviparous ( ovipar ).
Poison
The types of the genus are fairly uniformly described as less aggressive. The venom of the black otter mainly contains hemolytic , anticoagulant and muscle tissue destroying (myolytic) components. The average amount of venom per bite has been investigated for two species; it is given as 180 to 190 mg dry weight for the Mulga snake and 32 to 40 mg for P. porphyriacus . The poison is moderately effective; the LD 50 value in mice is 1.53–2.53 mg per kg.
Human deaths are very rare. A typical symptom after a bite is severe swelling of the bitten limb, which subsides after a few days. Other symptoms include nausea, vomiting, bleeding disorders and muscle destruction. In one documented death caused by a Mulga snake, death occurred 37 hours after the bite, the cause of death was extensive destruction of the heart muscle.
swell
Individual evidence
- ↑ The Reptile Database: Pseudechis weigeli (accessed June 28, 2018)
- ↑ Wüster, Wolfgang, Alex J. Dumbrell, Chris Hay, Catharine E. Pook, David J. Williams and Bryan Grieg Fry: Snakes across the Strait: trans-Torresian phylogeographic relationships in three genera of Australasian snakes (Serpentes: Elapidae: Acanthophis, Oxyuranus, and Pseudechis). Molecular Phylogenetics and Evolution 33 (3), 2004: 1-14, available under Archived Copy ( Memento of the original from February 24, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Shine, R. and J. Covacevich: Ecology of Highly Venomous Snakes: the Australian Genus Oxyuranus (Elapidae). Journal of Herpetology 17, Issue 1, 1983: pp. 60-69
- ↑ Mirtschin, PJ, GR Crowe and R. Davis: Dangerous Snakes Of Australia. In: P. Gopalakrishnakone, LM Chou: Snakes of Medical Importance. Venom and Toxin Research Group, National University of Singapore, 1990: 105 and 112
- ^ J. White: Venomous Snakes of Medical Importance in Australia: Clinical Toxicology. In: P. Gopalakrishnakone, LM Chou: Snakes of Medical Importance. Venom and Toxin Research Group, National University of Singapore, 1990: pp. 175-210
- ↑ Mirtschin, PJ, GR Crowe and R. Davis: Dangerous Snakes of Australia. In: P. Gopalakrishnakone, LM Chou: Snakes of Medical Importance. Venom and Toxin Research Group, National University of Singapore, 1990: pp. 114-115
literature
- PJ Mirtschin, GR Crowe, and R. Davis: Dangerous Snakes of Australia. In: P. Gopalakrishnakone, LM Chou: Snakes of Medical Importance. Venom and Toxin Research Group, National University of Singapore, 1990, ISBN 9971-62-217-3 , pp. 1-174.
- GM Storr, LA Smith and RE Johnstone: Snakes of Western Australia . Perth, 1986, ISBN 0-7309-0399-0 , pp. 87-89.
