Boom slang
| Boom slang | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Boom slang |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the genus | ||||||||||||
| Dispholidus | ||||||||||||
| Duvernoy , 1832 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Dispholidus typus | ||||||||||||
| ( A. Smith , 1829) |
The Boomslang ( Dispholidus typus ), sometimes also referred to as the African Tree Snake or Green Boomslang , is a species of snake from the family of the adder (Colubridae). The genus Dispholidus is monotypical , the Boomslang is the only species in the genus. It has fangs and is one of the so-called false snakes . The range of the species covers large parts of tropical Africa south of the Sahara to the south of South Africa .
The name Boomslang comes from Dutch (via Afrikaans ) and literally means: tree snake. The English language also describes this type of snake as boomslang ; the word is pronounced according to English pronunciation rules.
description
anatomy
Adult individuals usually reach overall lengths of 1.2 to 1.5 m, up to a maximum of 2.0 m. The animals are slim, the head is short and blunt, the eyes are enormous and very conspicuous in relation to the head.
Scaling
The animals usually have one primary and two secondary temporalia , one, rarely two praeocularia and usually 3, rarely 2 or 4 postocularia . They usually have 7, rarely 6 or 8 supralabials , of which the third and fourth, more rarely the fourth and fifth, are adjacent to the eye. The animals have 8–13 infralabiala . The dorsal scales are strongly keeled. The animals have 19, rarely 17 or 21 dorsal rows of scales in the middle of the body. The number of abdominal scales ( ventral shields ) varies between 164 and 201, the number of divided subcaudalia between 104 and 142. The anal shield is divided.
coloring
Adult animals show clear sex differences in terms of coloration. Males are very variable and usually marked more colorful and contrasting than the females, they come in four to five color types, between which there are also transitions:
- Upper side green to olive green, with or without black skin coloration between the scales, belly side similar to upper side, but lighter.
- Upper side light green with black edged scales, so that the snake is cross-banded.
- Upper side monochrome dark brown to black, belly side light yellow.
- Upper side black, belly scales dark gray with black edges
- Brick-red animals are occasionally found on top
Females are usually light to olive brown on the upper side and have a dirty white to brown underside, but occasionally they are as colorful as the males. Young animals are light gray to brown on top and show a fine blue speckle, especially in the front area of the body. The throat is bright yellow or orange, the rest of the underside is white to yellowish with dark spots. The iris is bright green. The color of adult animals is achieved with a length of about 1 m.
distribution and habitat
The range of the species covers large parts of tropical Africa south of the Sahara to the south of South Africa . In southern Africa, the Boomslang inhabits a wide range of habitats from the Karoo to wet and dry savannah , forests of the plains to grasslands and fynbos . She avoids the dry west and the central plateau (the highveld ) of South Africa.
Systematics
The genus Dispholidus is monotypical , the Boomslang is so far the only species in the genus. Due to morphological differences, however, the boomslangs on the island of Pemba are likely to represent a species of their own. Several subspecies have been described, but these are not recognized by DG Broadley and V. Wallach.
Lifestyle and diet
The Boomslang is predominantly diurnal and mostly hangs out on trees or bushes, where it is very well camouflaged by its color. Occasionally the ground is visited, for sunbathing or for hunting. The animals actively hunt predominantly in the higher vegetation, more rarely on the ground, especially in the vicinity of rivers. At the sight of suitable prey, the snake freezes with its head raised. It then snaps quickly and holds the prey with chewing movements until it dies from the poison. The diet consists mainly of chameleons and other tree-dwelling lizards, birds and their nestlings and eggs as well as frogs. Small mammals are rarely eaten. Of different birds, for example Bulbuls , Boom Langs are recognized as enemies and angehasst .
Reproduction
The Boomslang is oviparous (egg-laying), the clutch usually consists of 8 to 14, a maximum of 27 eggs. Eggs are laid from late spring to mid-summer in hollow trees, rotting wood or under piles of leaves. The young snakes are 29 to 38 cm long at birth.
Behavior towards people
The species is very shy and avoids people at an early stage due to its very good sense of sight. The animals only bite when they are touched. In the event of a direct threat, the animals first inflate the neck and thus present the colorful skin in this area. If the threat persists, they eventually inflate the whole body and snap shut with jerky lateral or forward movements.
Poison
effect
The poison is similar to that of the American lance viper . It has a hemolytic effect and, due to metalloproteinases, has a hemorrhagic effect (destroys blood vessels). The poison causes a change in the blood coagulation precursor fibrinogen through thrombin-like enzymes ( TLEs ) and thereby a pathological activation of blood coagulation . This leads to the rapid consumption of the coagulation factors via further steps and therefore has an anticoagulant effect . The syndrome is known as Disseminated Intravascular Coagulopathy (DIC). The patients bleed from the bite site and oral mucosa and internal bleeding occurs. The poison is apparently also directly toxic to the kidneys. The onset of effects is comparatively late; it can take 24–48 hours for serious symptoms to develop.
The average amount of poison per bite is comparatively low; it is given as a maximum of 1.5 mg dry weight. However, the boomslang's poison is extremely potent; the LD 50 value in mice after intravenous administration is 0.06-0.72 mg per kg.
The species can easily use the poison teeth, which are located far back in the mouth, when biting the arm or leg of a person, as it can open the mouth at an angle of up to 170 °. Bites that release a large amount of poison into the bite site are usually fatal for people without treatment with a specific antiserum .
Epidemiology
Despite its toxicity, the Boomslang is described as hardly relevant from a medical point of view due to its predominance in higher vegetation ( arboricol ) and its shyness. Bite accidents are very rare and mostly affect snake dealers and reptile keepers. The American herpetologist Karl Patterson Schmidt died in 1957 from the bite of a boomslang held in his institute in Chicago . Schmidt documented the details of his agony in his diary.
swell
Individual evidence
- ^ A b D. G. Broadley and V. Wallach: Review of the Dispholidini, with the description of a new genus and species from Tanzania (Serpentes, Colubridae). Bulletin of the Natural History Museum: Zoology 68, 2002: pp. 57-74.
- ↑ Aura S. Kamiguti, R. David G. Theakston, Nicholas Sherman and Jay W. Fox: Mass spectrophotometric evidence for P-III / P-IV metalloproteinases in the venom of the Boomslang (Dispholidus typus) Toxicon 38, No. 11, 2000 : Pp. 1613-1620 doi : 10.1016 / S0041-0101 (00) 00089-1
- ↑ Stephen P. Mackessy: Biochemistry and Pharmacology of Colubrid Snake Venoms. J. Toxicol.— Toxin Reviews 21 (1 & 2), 2002: pp. 43–83 online as pdf ( memento of the original from June 2, 2010 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.
- ^ J. Marais: A Complete Guide to the Snakes of Southern Africa. Struik Publishers, Cape Town, 2004: p. 137.
- ↑ Short biography on "Scientific and Common Names of the Reptiles and Amphibians of North America - Explained"
literature
- J. Marais: A Complete Guide to the Snakes of Southern Africa. Struik Publishers, Cape Town, 2004: pp. 135-137. ISBN 1-8-6872-932-X
