Bushmaster
| Bushmaster | ||||||||||||
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Lachesis muta muta |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Lachesis | ||||||||||||
| Daudin , 1803 |
Bushmasters ( Lachesis ) are a genus of snakes from the subfamily of pit vipers . The genus occurs with four kinds in Central America and in northern South America. All species are tied to the forest and live on the ground. The species are poisonous, but bite accidents are rare due to the low level of aggressiveness and the withdrawn way of life of the animals. The bite often leads to severe poisoning in humans, but usually not to death. The genus is named after a Greek goddess of fate ( Lachesis ).
features
anatomy
All bushmasters are very large, medium-slender pit vipers. The body is usually compressed at the sides. The head is large and rather elongated, but not very clearly separated from the neck, the eyes are relatively small. The snout is usually broadly rounded, the tip of the snout is not elongated. The canthus is rounded. The tail is not suitable for grasping. All species regularly have total lengths of more than 1.9 m, the maximum secured dimensions are between 2.32 m and 3.0 m total length. Bushmasters are the largest vipers in the world and the largest venomous snakes in America.
Scaling
The rostral is usually roughly triangular and just as wide or wider than it is high. There are three praeocularia , the upper one of which is significantly larger than the others. The supraocularia are large and elongated and separated from each other by 10–15 rounded intersupraocularia . There are 2-3 Canthalia on each side. The top of the head is covered with small, mostly keeled scales. The number of supralabials is 7 to 11, the number of infralabials 11 to 17. The number of ventral scales ( ventral shields ) varies between 191 and 236, the number of divided subcaudalia between 31 and 56. The posterior subcaudalia are thorny in 4–5 rows Shed shared. The number of dorsal rows of scales in the middle of the body fluctuates between 21 and 27. The scales in the middle of the back have clearly raised, rounded keels.
coloring
Bushmasters are very appealing in terms of color. The basic color of the top is variable pink-brownish, orange-brownish, red-brown or yellowish. For this reason, the animals show a series of very distinctive, large, dark brown or black, more or less rhombic spots on their backs . These lie transversely to the longitudinal axis of the animals and taper off more or less pointedly on the lower flanks. The spots often show bright centers or are more or less interrupted. Depending on the species, the top of the head is monochrome like the rest of the basic body color, darkly spotted or completely black. The sides of the head show a wide, dark postocular stripe that extends from the back of the eye to behind the corner of the nose.
distribution and habitat
Bush masters are common in Central America and northern South America. The distribution area extends from central Nicaragua south to central Bolivia and to the east of Brazil . Two of the four species have relatively small areas in Central America; the L. muta area covers large parts of northern South America. Bushmasters are inhabitants of the original, tropical rainforest up to an altitude of about 1600 m.
Systematics
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Campbell & Lamar recognize 4 types:
- Lachesis acrochorda (García 1896); Eastern Panama, Western Colombia, Northwest Ecuador.
- Lachesis melanocephala Solòrzano & Cerdas 1986; southeastern Costa Rica and adjacent areas in western Panama.
- Lachesis muta (Linnaeus 1766): Amazon basin, Guiana shield (subspecies L. m. Muta ), southeastern Brazilian coastal rainforest (subspecies L. m. Rhombeata ).
- Lachesis stenophrys Cope 1875: Nicaragua, Costa Rica, Panama.
Until a few years ago, L. muta was the only species of the genus Lachesis with four subspecies . On the basis of a molecular genetic investigation, two of the subspecies ( L. melanocephala and L. stenophrys ) were separated from L. muta as separate species in 1997 . The fourth species was separated from Cambell & Lamar L. acrochorda in 2004 .
A molecular genetic investigation including 2 of the 4 species has also confirmed the monophyly of the genus Lachesis within the pit vipers, a molecular genetic investigation including all four species is not yet available.
Lifestyle, Diet and Reproduction
All species of the genus are almost exclusively nocturnal and live on the ground. The day is spent in mammalian burrows, under fallen trees and in similar places. The animals often stay in the same hiding place for several days or weeks. Bushmasters are ambush hunters who often stay in the same place for days. The diet apparently consists almost exclusively of smaller mammals, especially mice , but also marsupials and squirrels .
In contrast to all other pit vipers in America, Bushmasters lay eggs ( oviparous ). The eggs are laid in the caves, which are also used as daytime hiding places, the females wrap around the clutch until the young snakes hatch. The clutches include 6-11, up to a maximum of 20 eggs. Depending on the author, the time to hatching is specified as 60 to 90 days.
Poison
Bushmasters are evidently neither particularly aggressive nor do they seek out human settlement. As a result, bite accidents are rare compared to species of American lanceolers and rattlesnakes found in the same range . Bushmaster bites accounted for only 2% of all snake poisoning, according to a survey in Colombia. Even in a specialized center in Manaus , Brazil , where 200 bite accidents are treated annually, only 10 bites by L. muta were documented over several years . Information from the government of Brazil, cited several times in the literature, which attributes 15,000 bite accidents nationwide to L. muta over a period of 4.5 years, therefore considers David Warell to be implausible.
The poison is not very toxic, and despite the size of the animals, the amount of poison is usually much less than that of the significantly smaller individuals of the American lance viper. The typical symptoms of poisoning are described in a relatively uniform way: initial nausea, severe intestinal cramps, repeated vomiting, watery diarrhea and profuse sweating. In addition, swelling and rarely bleeding disorders or necrosis can occur. The data on the frequency of deaths are extremely contradictory. While, according to a retrospective study in Costa Rica, three of a total of four bitten people died, from the other countries within the area of distribution individual, sometimes severe poisonings have become known, but only one confirmed death in Colombia.
swell
Individual evidence
- ↑ KR Zamudio and HW Greene: Phylogeography of the bushmaster (Lachesis muta: Viperidae): implications for neotropical biogeography, systematics, and conservation. Biological Journal of the Linnean Society, 62, 1997: pp. 421-442
- ^ David A. Warrell: Snakebites in Central and South America: Epidemiology, Clinical Features, and Clinical Management . In: Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London. 2004: p. 751.
literature
- David A. Warrell: Snakebites in Central and South America: Epidemiology, Clinical Features, and Clinical Management . In: Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London. 2004. ISBN 0-8014-4141-2 : pp. 709-761.
- Jonathan A. Campbell, William W. Lamar: The Venomous Reptiles of the Western Hemisphere. Comstock; Ithaca, London; 2004 ISBN 0-8014-4141-2
