- Boomslang
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For other uses, see Boomslang (disambiguation).
Boomslang 
Conservation status Scientific classification Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Reptilia Order: Squamata Suborder: Serpentes Family: Colubridae Subfamily: Colubrinae Genus: Dispholidus Species: D. typus Binomial name Dispholidus typus
(A. Smith, 1829)Synonyms The boomslang (Dispholidus typus) is a large venomous colubrid snake.[2]
Contents
Taxonomy & etymology
It is currently the only species in its genus, although several species and subspecies have been described in the past. Its name means "tree snake" in Afrikaans and Dutch[3] (boom meaning "tree" [a cognate of "beam", which means a long and large piece of wood, generally a support in a building], and slang meaning "snake"). In Afrikaans, the name is pronounced [buˑomslʌŋ]. The snake is thought to be closely related to members of the genera Thelotornis, Thrasops, Rhamnophis, and Xyelodontophis, with which it forms the taxonomic tribe Dispholidini.[4]
Description
The average adult boomslang is 100-160 cm (3¼-5¼ feet) in total length, but some exceed 183 cm (6 feet). The eyes are exceptionally large, and the head has a characteristic egg-like shape. Coloration is very variable. Males are light green with black or blue scale edges, but adult females may be brown.[5]
The head is distinct from the neck. The canthus rostralis is distinct. The pupil of the very large eye is round. The maxillary teeth are small anteriorly, 7 or 8, followed by three very large grooved fangs situated below the eye. The mandibular teeth are subequal. The body is slightly compressed. The dorsal scales are very narrow, oblique, strongly keeled, with apical pits, arranged in 19 or 21 rows. The tail is long, and the subcaudals are paired. Ventrals are 164-201; the anal plate is divided; and the subcaudals are 91-131.[6]
Geographic range
The boomslang is native and restricted to sub-Saharan Africa.
Reproduction
Boomslangs are oviparous. The eggs have a relatively long (3 months on average) incubation period. Hatchlings are greyish with blue speckles. They attain their adult coloration after several years.
Behavior and diet
Boomslangs are diurnal and largely arboreal. Their diet includes chameleons and other arboreal lizards,[2] frogs, and occasionally small mammals, birds, and eggs from nesting birds,[2] all of which they swallow whole. During cool weather, they will hibernate for moderate periods, often curling up inside the enclosed nests of birds such as weavers.
Venom
Many venomous members of the family Colubridae are harmless to humans because of small venom glands, weak venom, or inefficient fangs. However, the boomslang is a notable exception in that it has a highly potent venom, which it delivers through large fangs that are located in the back of the jaw.[2] Boomslangs open their jaws 90 degrees when biting. The venom of the boomslang is primarily a hemotoxin; it disables the blood clotting process and the victim may well die as a result of internal and external bleeding.[2][7] Other signs and symptoms include headache, nausea, sleepiness and mental disorders.
Because the venom is slow to act, symptoms may not be manifest until many hours after the bite. On one hand, this provides time for procuring the antivenom, while on the other it may lead victims to underestimate the seriousness of the bite. Snakes of any species may sometimes fail to inject venom when they bite, so after a few hours without any noticeable effects, victims of boomslang bites may believe (wrongly) their injury is not serious.
An adult boomslang has 1.6–8 mg of venom.[8] Various sources give figures ranging from 0.06 - 0.72 mg/kg being sufficient to kill mice in 50% of cases, if the venom reaches a vein (LD50).[9]
In 1957, well-known herpetologist Karl Schmidt died after being bitten by a boomslang. D.S. Chapman states that between 1919 and 1962 there were eight serious human envenomations by boomslangs, two of which were fatal. The South African Vaccine Producers (formerly South African Institute of Medical Research) manufactures a monovalent antivenin for use in boomslang envenomations.
The boomslang is a timid snake, and bites generally occur only when people attempt to handle, catch or kill the animal. The above data suggest boomslangs are unlikely to be a significant source of human fatalities throughout their distribution range.
In popular culture
A male boomslang
- Shredded skin of a boomslang is one of the ingredients to make the Polyjuice Potion in J.K. Rowling's Harry Potter and the Chamber of Secrets.
- The venom of the boomslang also features in the Agatha Christie thriller, Death in the Clouds (pub.1935), featuring her famous detective, Hercule Poirot.
- A distillation of boomslang venom is combined with dimethyl sulfoxide to create a contact poison that is the murder weapon in an episode of Quincy, ME.
- A character named Boomslang is a Marvel Comics supervillain.
- Boomslang is the title of a 2003 album by former Smiths guitarist and songwriter Johnny Marr, credited to Johnny Marr and the Healers.
- In the video game Warriors Orochi, the main villain, Orochi (portrayed as a snake-like demon), has many subordinate generals named after snakes; Boomslang is one.
References
- ^ Boulenger, G.A. 1896. Catalogue of the Snakes in the British Museum (Natural History), Volume III. London. pp. 186-189.
- ^ a b c d e Encyclopædia Britannica. Encyclopædia Britannica, Inc.. 2007.
- ^ Oxford English Dictionary. Oxford, England: Oxford University Press. 1989.
- ^ Broadley, Donald; Wallach, Van (November 2002). "Review of the Dispholidini, with the description of a new genus and species from Tanzania (Serpentes, Colubridae)". Bull. Nat. Hist. Mus. Lond. (Zool.) 68 (2): 57–74. doi:10.1017/S0968047002000079.
- ^ http://www.tigerhomes.org/animal/boomslang-snake.cfm
- ^ Boulenger, G.A. 1896. Catalogue of the Snakes in the British Museum (Natural History), Volume III. London. pp. 186-189.
- ^ Kamiguti, AS; Theakston RD, Sherman N, Fox JW (November 2000). "Mass spectrophotometric evidence for P-III/P-IV metalloproteinases in the venom of the boomslang (Dispholidus typus)". Toxicon 38 (11): 1613–1620. doi:10.1016/S0041-0101(00)00089-1. PMID 10775761.
- ^ LD50 for various snakes
- ^ Stephen P. Mackessy: Biochemistry and Pharmacology of Colubrid Snake Venoms. J. Toxicol.—Toxin Reviews 21 (1&2), 2002: pp. 43–83 online PDF
External links
Categories:- IUCN Red List least concern species
- Colubrids
- Reptiles of Africa
- Dutch loanwords
- Venomous snakes
- Monotypic reptile genera
- Animals described in 1829
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