Venomous snake
As poisonous snakes are snakes referred to the hunt for prey and defend toxins used. The poison injected during the bite kills the prey or at least poisons an attacker. Of the 3400 species of snakes known worldwide , significantly more than the often rumored 10% (~ 340 species) are poisonous. The complete families of the poisonous snakes (Elapidae) and the vipers (Viperidae) as well as the terrestrial vipers (Atractaspidinae) are proven to be poisonous . According to the Reptile Database (as of May 2014) there are currently 351 species of poisonous snakes, 321 species of vipers and 22 species of terrestrial vipers known. These families only contain venomous snakes. There are already 694 venomous snakes known from these three families alone. In addition, there are various other poisonous snakes from other families, such as the boomslang from the adder family.
Biting and spitting
The venomous teeth of the snakes are in the front (foldable back into the mouth or fixed) or in the back of the upper jaw. After a certain period of time, the teeth are replaced by other teeth that are pushed forward and fall out. The poison is formed in the upper lip glands and is injected into the prey when it is bitten. The venom can act either on the central nervous system ( neurotoxic ) or on the blood and tissue ( hemotoxic ) of the victim, and in some species of snakes (e.g. the Gaboon viper ) both. Neurotoxic poisons have a paralyzing effect and limit the function of the respiratory organs, which can lead to death by suffocation. Hemotoxic toxins attack the blood cells and tissues.
After the attack, most of the snakes will retreat and wait for the animal to be dead or paralyzed. When devouring, the snake releases poison into the prey several times. Snake venoms also contain enzymes that are used to digest prey.
A dry bite is a bite that does not inject venom.
Spitting cobras can inject their poison against the attacker as a defense, aiming at the face. Ineffective on intact skin, it causes severe pain in the eyes and impaired vision, with long-term damage up to blindness possible if left untreated. Its composition is similar to that of other poisonous snakes.
Venomous snakes and people
There is no reliable information on the number of deaths caused by poisonous snakes worldwide each year; a more recent estimate gives 21,000 to 94,000 deaths per year. Other estimates assume 100,000 deaths worldwide per year, and another 300,000 bite victims suffer chronic damage. Every year around 5 million people around the world are bitten by poisonous snakes, mostly women, children and farmers in poor and rural areas of the tropics. The development of powerful serums has helped reduce deaths.
Furthermore, snake venom is often used for medical purposes, for example to produce antibodies and to fight viruses .
Venomous snakes are also used as pets , whereby it is important to keep them appropriately . Inappropriate keeping is torture for the animal. In many parts of the EU the keeping of poisonous wild animals is subject to official approval. Negligent behavior can endanger other people. Furthermore, permission from the landlord is required and a violation can lead to the termination of the lease.
Systematics
Venomous snakes are found in the following families :
-
Poisonous snakes (Elapidae) with two subfamilies:
- Poisonous snakes (Elapinae), to which z. B. the mambas ( Dendroaspis sp. ), Cobras ( Naja sp. ) And the New World coral otters ( Micrurus sp. ) Belong
- Sea snakes (Hydrophiinae), which together with the land-living Australo-Asian poisonous snakes form a taxon within the Elapidae. Examples: row snakes ( Hydrophis sp. ), Flattails ( Laticauda sp. ), Taipans ( Oxyuranus sp. ), Brown snakes ( Pseudonaja sp. ) And tiger otters ( Notechis sp. )
-
Vipers (Viperidae) with four subfamilies:
- Real vipers (Viperinae), represented in Central Europe by adder ( Vipera berus ), aspis viper ( Vipera aspis ) and meadow viper ( Vipera ursinii ). Other genera are z. B. the puff adders ( Bitis sp. ) And the sand rattle otters ( Echis sp. )
- Pit vipers (Crotalinae), represented in America by rattlesnakes ( Crotalus sp. ), Triangular-headed vipers ( Agkistrodon sp. ) And lance vipers ( Bothrops sp. ), In Asia with bamboo otters ( Trimeresurus sp. ) Or Halys otters ( Gloydius) sp. ), in Africa with the toad vipers ( Causus )
- primeval vipers (Azemiopinae) from Asia with the Fea viper ( Azemiops feae ) and Azemiops kharini ( white-headed Fea viper ) as the only representatives of their species
- Erdvipern (Atractaspididae), in which some genera or species are summarized that were previously assigned to other families, z. B. Mueller's earth viper ( Micrelaps muelleri )
In the family of snakes (Colubridae) there are some snakes behind permanent furrows fangs, as deceit snakes are called, but do not form a separate taxon. While the hooded snakes ( Macroprotodon sp. ) Or the cat snakes ( Telescopus sp. ), Which are also widespread in southern Europe, only have a weak poison, the African boomslang ( Dispholidus typus ), the liana snake ( Thelotornis kirtlandi ) and the mangrove Night tree snake ( Boiga dendrophila ) become dangerous to humans.
Ranking according to the strength of the poison
The most venomous snakes are found in Australia and in the sea ( sea snakes ). The island Queimada Grande off the east coast of Brazil is considered to have the highest density of venomous snakes .
The world's most venomous snake is inland taipan, native to Australia . Inland Taipan's best-known competitors for the question of the more potent poison are the beaked sea snake ( Enhydrina schistosa ) and Dubois' sea snake ( Aipysurus duboisii ). However, the LD50 of the beaked sea snake is just over 0.1 mg / kg, while Dubois' sea snake reaches 0.044 mg / kg.
In the case of the eastern brown snake ( Pseudonaja textilis ) (also native to Australia ), an LD50 value of around 0.037 mg / kg was determined.
| Scientific name | German name |
subcutaneous mg / kg |
intravenous mg / kg |
intraperitoneal mg / kg |
|---|---|---|---|---|
| Oxyuranus microlepidotus | Inland Taipan | 0.025 | ||
| Pseudonaja textilis | Eastern brown snake | 0.0365 | ||
| Oxyuranus scutellatus | Taipan | 0.106 | ||
| Bungarus multicinctus | Multi-tie bungary | 0.1080 | 0.113 | 0.08 |
| Boulengerina christyi | Congo water cobra | 0.1200 |
It should be noted here that the results of such measurements differ depending on the animal and the type of measurement. The results presented here are therefore not absolute.
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- ↑ reptile-database: Species Numbers (February 2014)
- ↑ Anuradhani Kasturiratne, A. Rajitha Wickremasinghe, Nilanthi de Silva, N. Kithsiri Gunawardena, Arunasalam Pathmeswaran1, Ranjan Premaratna, Lorenzo Savioli, David G. Lalloo, H. Janaka de Silva: The Global Burden of Snakebite: A Literature Analysis and Modeling Based on Regional Estimates of Envenoming and Deaths. PLoS Medicine Vol. 5, No. 11, e218, doi: 10.1371 / journal.pmed.0050218 .
- ↑ Süddeutsche Zeitung, May 6, 2010, p. 18
- ↑ LD50 values for snakes, 2014 , accessed April 25, 2014
- ↑ Dr. Bryan Grieg Fry, Snake LD50 (en) ( Memento of the original from July 24, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Accessed June 11, 2007
- Mark O'Shea: Venomous snakes. All species in the world in their habitats. Franckh-Kosmos Verlag, Stuttgart 2006, ISBN 3-440-10619-5 .
