Boomslang

Last updated • 6 min readFrom Wikipedia, The Free Encyclopedia

Boomslang
Dispholidus typus.jpg
Male at campsite in the Ngorongoro Conservation Area
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Dispholidus
Species:
D. typus
Binomial name
Dispholidus typus
(A. Smith, 1828)
Boomslang
Boomslang distribution
  Extant (resident)
Synonyms [1]
  • Bucephalus typus
    A. Smith, 1828
  • Dispholidus typus
    —Boulenger, 1896

The boomslang ( /ˈboʊmslɑːŋ/ or /ˈbɔːmsləŋ/ ; Dispholidus typus) is a highly venomous snake in the family Colubridae. [2] The species is native to Sub-Saharan Africa.

Contents

Etymology

Its common name means "tree snake" in Dutch [3] and Afrikaans – boom meaning "tree", and slang meaning "snake". In Afrikaans, the name is pronounced [ˈbuəmslaŋ] .

Taxonomy

The boomslang is a colubrid snake within the subfamily Colubrinae. It belongs to the genus Dispholidus , which contains two other species, D. pembae and D. punctatus .

The boomslang 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]

Close relationships can be shown in the cladogram below: [5]

Oligodon

Subspecies

Two subspecies are recognised, including the nominotypical subspecies. [6]

The trinomial authority in parentheses for D. t. typus indicates that the subspecies was originally described in a genus other than Dispholidus.

Description

Raiding the communal nest of sociable weavers Dispholidus typus 118135525.jpg
Raiding the communal nest of sociable weavers

The average adult boomslang is 100–160 centimetres (3.3–5.2 ft) in total length (including tail). Some exceed 183 centimetres (6.00 ft). The eyes are exceptionally large, and the head has a characteristic egg-like shape. Colouration is highly variable. Males are light green with black or blue scale edges, but adult females may be brown demonstrating sexual dimorphism. [7]

Weight varies from 175 to 510 g (0.386 to 1.124 lb), with an average weight of 299.4 g (0.660 lb). [8]

In this species, the head is distinct from the neck and the canthus rostralis is distinct. The pupil of the very large eye is round. The boomslang has excellent eyesight and often moves its head from side to side to get a better view of objects directly in front. The maxillary teeth are small anteriorly, seven or eight in number, followed by three very large, grooved fangs situated below each eye. The mandibular teeth are subequal. The body is slightly compressed. The dorsal scales, which are arranged in 19 or 21 rows, are very narrow, oblique, strongly keeled, with apical pits. The tail is long, and the subcaudal scales are paired. Ventral scales are 164–201; the anal plate is divided; and the subcaudals are 91–131. [1]

Geographic range

Boomslang in typical natural habitat. In South Africa Boomslang.jpg
Boomslang in typical natural habitat. In South Africa

The boomslang is endemic to Sub-Saharan Africa, from The Gambia, Guinea, Senegal and most of Western Africa (including Benin, Cameroon, Ghana, Nigeria, Togo) [9] through Central and Eastern Africa (Democratic Republic of the Congo, western Ethiopia, Kenya, South Sudan, Tanzania, Uganda). It is found across much of Southern Africa, in a wide array of habitats, with some of the species' densest populations being in Angola, Botswana, Eswatini, Malawi, Mozambique, Namibia, South Africa, Zambia and Zimbabwe. [9]

Habitat

The boomslang is an excellent climber and is highly arboreal, living mainly in forested areas. D. typus lives in karoo shrubs, savannahs, lowland forests, and in grasslands. The boomslang is not restricted to trees and can often be found on the ground hunting, feeding, or taking shelter. It will occasionally hide underground when the weather is harsh. [10]

Reproduction

The boomslang is oviparous, and an adult female can produce up to 30 eggs, which are deposited in a hollow tree trunk or rotting log. The eggs have a relatively long (3 months on average) incubation period. Male hatchlings are grey with blue speckles, and female hatchlings are pale brown. They attain their adult colouration after several years. Hatchlings are about 20 cm (7.9 in) in length and pose no threat to humans, but are dangerously venomous by the time they reach a length around 45 cm (18 in) and a girth as thick as an adult's smallest finger.

Behaviour and diet

D. t. typus feeding on a Cape weaver chick. Common Boomslang, South Cape DC, South Africa imported from iNaturalist photo 54362526.jpg
D. t. typus feeding on a Cape weaver chick.

D. typus is diurnal and almost exclusively arboreal. It is reclusive, and moves from branch to branch when pursued by anything too large to eat. Its diet includes chameleons and other arboreal lizards, [2] frogs, and occasionally small mammals, birds, and eggs from nesting birds and reptiles, [2] [11] all of which it swallows whole. The boomslang will also feed on other snakes, including cannibalising members of its own species. [11] During cool weather, the boomslang brumates for short periods, often curling up inside the enclosed nest of a weaverbird.

Venom

Many venomous species of the Colubridae are harmless to humans—unless one has a known rare allergy—largely because of small venom glands and inefficient teeth that are situated at the back of the mouth. These species, including the boomslang, are collectively known as "rear-fanged" (or opisthoglyphous) snakes, as their venom-injecting teeth are situated farther back in the mouth than elapids or vipers, and thus require the snake to bite, hold-on, and "chew" the venom into its victim.

However, some opisthoglyphous snakes—including the boomslang—actually possess a highly potent and toxic venom. [2] The boomslang is able to open its jaws up to 170° when biting, facilitating envenomation. [12] The venom of the boomslang is primarily a hemotoxin; it works via a process in which many small clots form in the blood, causing the victim's circulatory system to improperly coagulate, resulting in excessive bleeding and death. The venom has been observed to cause bleeding in tissues such as muscle and the brain (among other organs), while, at the same time, clogging capillaries with tiny blood clots. [2] [13] Other signs and symptoms include headache, nausea, sleepiness, and confusion, leading to cardiac arrest and unconsciousness.

Because boomslang venom is slow-acting, symptoms may not become apparent until many hours after a bite. Although the absence of symptoms provides sufficient time for procuring antivenom, it can also provide victims with false reassurances, leading to underestimation of the seriousness of the bite. Snakes of any species may sometimes fail to inject venom when they bite (a so-called "dry bite" or "bluff strike", enacted in-defense), wherein, after a few hours without any noticeable effects, victims of boomslang bites may falsely believe that their attack was simply a dry or bluff strike. The pathophysiological mechanisms of the venom are different with every snake, resulting in different clinical manifestations with every patient.

An adult boomslang has 1.6 to 8 mg of venom. [14] Its median lethal dose (LD50) in mice is 0.1 mg/kg (intravenously). [15] 0.071 mg/kg (IV) has also been reported. [16] 12.5 mg/kg (subcutaneously) and 1.3–1.8 mg/kg (intraperitoneal). [17] Based on the very low venom quantities produced by D. typus, and the very serious effects found in a good part of the reported cases in humans, it has been suggested that the venom's LD50 is lower in humans than in mice, with only 2 to 3 mg being enough to potentially kill a healthy adult. [18]

In 1957, herpetologist Karl Schmidt died after being bitten by a juvenile boomslang, which he had doubted could produce a fatal dose. [19] [20] He made notes on the symptoms he experienced almost to the end. [21] [22] D. S. Chapman reported eight serious envenomations by boomslangs between 1919 and 1962, two of which were lethal. [23]

Boomslang monovalent antivenom was developed during the 1940s. The South African Vaccine Producers manufactures a monovalent antivenom for use in boomslang envenomations. [24] Treatment of bites may also require complete blood transfusions, especially if over 24-48 hours have passed without antivenom.

The boomslang is a timid snake, and bites generally occur only when people attempt to handle, catch, pursue or kill the animal. When confronted and cornered, it inflates its neck and assumes an S-shaped striking pose, a key indicator of any snake species feeling threatened.

Related Research Articles

<span class="mw-page-title-main">Mamba</span> Genus of venomous snakes

Mambas are fast-moving, highly venomous snakes of the genus Dendroaspis in the family Elapidae. Four extant species are recognised currently; three of those four species are essentially arboreal and green in colour, whereas the black mamba, Dendroaspis polylepis, is largely terrestrial and generally brown or grey in colour. All are native to various regions in sub-Saharan Africa and all are feared throughout their ranges, especially the black mamba. In Africa there are many legends and stories about mambas.

<i>Bungarus</i> Genus of venomous snakes

Bungarus is a genus of venomous snakes in the family Elapidae. The genus is native to Asia. Often found on the floor of tropical forests in South Asia, Southeast Asia and Southern China, they are medium-sized, highly venomous snakes with a total length typically not exceeding 2 metres. These are nocturnal ophiophagious predators which prey primarily on other snakes at night, occasionally taking lizards, amphibians and rodents. Most species are with banded patterns acting as a warning sign to their predators. Despite being considered as generally docile and timid, kraits are capable of delivering highly potent neurotoxic venom which is medically significant with potential lethality to humans. The genus currently holds 18 species and 5 subspecies.

<span class="mw-page-title-main">Snakebite</span> Injury caused by bite from snakes

A snakebite is an injury caused by the bite of a snake, especially a venomous snake. A common sign of a bite from a venomous snake is the presence of two puncture wounds from the animal's fangs. Sometimes venom injection from the bite may occur. This may result in redness, swelling, and severe pain at the area, which may take up to an hour to appear. Vomiting, blurred vision, tingling of the limbs, and sweating may result. Most bites are on the hands, arms, or legs. Fear following a bite is common with symptoms of a racing heart and feeling faint. The venom may cause bleeding, kidney failure, a severe allergic reaction, tissue death around the bite, or breathing problems. Bites may result in the loss of a limb or other chronic problems or even death.

<span class="mw-page-title-main">Inland taipan</span> Venomous snake native to Australia

The inland taipan, also commonly known as the western taipan, small-scaled snake, or fierce snake, is a species of extremely venomous snake in the family Elapidae. The species is endemic to semiarid regions of central east Australia. Aboriginal Australians living in those regions named the snake dandarabilla. It was formally described by Frederick McCoy in 1879 and then by William John Macleay in 1882, but for the next 90 years, it was a mystery to the scientific community; no further specimens were found, and virtually nothing was added to the knowledge of this species until its rediscovery in 1972.

<span class="mw-page-title-main">Black mamba</span> Species of venomous snake

The black mamba is a species of highly venomous snake belonging to the family Elapidae. It is native to parts of sub-Saharan Africa. First formally described by Albert Günther in 1864, it is the second-longest venomous snake after the king cobra; mature specimens generally exceed 2 m and commonly grow to 3 m (9.8 ft). Specimens of 4.3 to 4.5 m have been reported. Its skin colour varies from grey to dark brown. Juvenile black mambas tend to be paler than adults and darken with age. Despite the common name, the skin of a black mamba is not black; the color name describes rather the inside of its mouth, which it displays when feeling threatened.

<span class="mw-page-title-main">Eastern green mamba</span> Species of venomous snake

The eastern green mamba is a highly venomous snake species of the mamba genus Dendroaspis native to the coastal regions of southern East Africa. Described by Scottish surgeon and zoologist Andrew Smith in 1849, it has a slender build with a bright green back and green-yellow ventral scales. Adult females average around 2 metres in length, and males are slightly smaller.

<span class="mw-page-title-main">Western green mamba</span> Species of snake

The western green mamba is a long, thin, and highly venomous snake species of the mamba genus, Dendroaspis. This species was first described in 1844 by American herpetologist Edward Hallowell. The western green mamba is a fairly large and predominantly arboreal species, capable of navigating through trees swiftly and gracefully. It will also descend to ground level to pursue prey such as rodents and other small mammals.

<i>Oxybelis fulgidus</i> Species of snake

(not to be confused with the Asian genus Ahaetulla, which are also referred as 'vine snakes')

<i>Naja</i> Genus of snakes

Naja is a genus of venomous elapid snakes commonly known as cobras. Members of the genus Naja are the most widespread and the most widely recognized as "true" cobras. Various species occur in regions throughout Africa, Southwest Asia, South Asia, and Southeast Asia. Several other elapid species are also called "cobras", such as the king cobra and the rinkhals, but neither is a true cobra, in that they do not belong to the genus Naja, but instead each belong to monotypic genera Hemachatus and Ophiophagus.

<i>Rhamnophis</i> Genus of snakes

Rhamnophis is a genus of arboreal venomous snakes, commonly known as dagger-tooth tree snakes or large-eyed tree snakes, in the family Colubridae. The genus is endemic to equatorial sub-Saharan Africa. There are two recognized species.

<span class="mw-page-title-main">Horned adder</span> Species of snake

The horned adder is a viper species. It is found in the arid region of southwest Africa, in Angola, Botswana, Namibia; South Africa, and Zimbabwe. It is easily distinguished by the presence of a single, large horn-like scale over each eye. No subspecies are currently recognized. Like all other vipers, it is venomous.

<i>Micrurus fulvius</i> Species of snake

Micrurus fulvius, commonly known as the eastern coral snake, common coral snake, American cobra, and more, is a species of highly venomous coral snake in the family Elapidae. The family also contains the cobras and sea snakes. The species is endemic to the southeastern United States. It should not be confused with the scarlet snake or scarlet kingsnake, which are harmless mimics. No subspecies are currently recognized.

<i>Telescopus</i> Genus of snakes

Telescopus, the Old World catsnakes, is a genus of 12 species of mildly venomous opisthoglyphous snakes in the family Colubridae.

<i>Tachymenis</i> Genus of snakes

Tachymenis is a genus of venomous snakes belonging to the family Colubridae. Species in the genus Tachymenis are commonly known as slender snakes or short-tailed snakes and are primarily found in southern South America. Tachymenis are rear-fanged (opisthoglyphous) and are capable of producing a medically significant bite, with at least one species, T. peruviana, responsible for human fatalities.

<span class="mw-page-title-main">Jameson's mamba</span> Species of snake

Jameson's mamba is a species of highly venomous snake in the family Elapidae. The species is native to equatorial Africa. A member of the mamba genus, Dendroaspis, it is slender with dull green upper parts and cream underparts and generally ranges from 1.5 to 2.2 m in total length. Described by Scottish naturalist Thomas Traill in 1843, it has two recognised subspecies. The nominate subspecies is found in central and western sub-Saharan Africa, and the eastern black-tailed subspecies is found eastern sub-Saharan Africa, mainly western Kenya.

<span class="mw-page-title-main">Epidemiology of snakebites</span>

Most snakebites are caused by non-venomous snakes. Of the roughly 3,700 known species of snake found worldwide, only 15% are considered dangerous to humans. Snakes are found on every continent except Antarctica. There are two major families of venomous snakes, Elapidae and Viperidae. 325 species in 61 genera are recognized in the family Elapidae and 224 species in 22 genera are recognized in the family Viperidae, In addition, the most diverse and widely distributed snake family, the colubrids, has approximately 700 venomous species, but only five genera—boomslangs, twig snakes, keelback snakes, green snakes, and slender snakes—have caused human fatalities.

<i>Philodryas olfersii</i> Species of snake

Philodryas olfersii is a species of venomous snake in the family Colubridae. The species is endemic to South America.

<span class="mw-page-title-main">Large-eyed green tree snake</span> Species of snake

The large-eyed green tree snake, also known commonly as the splendid dagger-tooth tree snake, is a species of venomous snake in the subfamily Colubrinae of the family Colubridae. The species is endemic to Africa. There are three recognized subspecies.

The spotted dagger-tooth tree snake is a species of venomous snake in the family Colubridae. The species is indigenous to Middle Africa.

References

  1. 1 2 Boulenger GA (1896). Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the Colubridæ (Opisthoglyphæ and Proteroglyphæ) .... London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I-XXV. (Genus Dispholidus, pp. 186-187; species Dispholidus typus, pp. 187–189, Figure 14).
  2. 1 2 3 4 5 Encyclopædia Britannica . Encyclopædia Britannica, Inc. 2007. ISBN   9781593392925.
  3. ↑ Oxford English Dictionary. Oxford, England: Oxford University Press. 1989.
  4. ↑ Broadley, D.G.; Wallach, V. (2002). "Review of the Dispholidini, with the description of a new genus and species from Tanzania (Serpentes, Colubridae)". Bulletin of the Natural History Museum, Zoology Series. 68 (2). doi:10.1017/S0968047002000079.
  5. ↑ Figueroa, A.; McKelvy, A. D.; Grismer, L. L.; Bell, C. D.; Lailvaux, S. P. (2016). "A species-level phylogeny of extant snakes with description of a new colubrid subfamily and genus". PLOS ONE . 11 (9): e0161070. Bibcode:2016PLoSO..1161070F. doi: 10.1371/journal.pone.0161070 . PMC   5014348 . PMID   27603205.
  6. ↑ Species Dispholidus typus at The Reptile Database . www.reptile-database.org.
  7. ↑ "Boomslang". African Snakebite Institute. 22 October 2017. Retrieved 4 May 2021.
  8. ↑ Grassy E MD (June 22, 1940). "Studies on the Venom of the Boomslang". South African Medical Journal.
  9. 1 2 "Observations • iNaturalist" . Retrieved 12 May 2024.
  10. ↑ "Boomslang Snake Facts [Ultimate Guide]". 2011-11-19. Archived from the original on 2022-03-31. Retrieved 2022-04-11.
  11. 1 2 "ADW: Dispholidus typus: INFORMATION". Animal Diversity Web .
  12. ↑ Marais, Johan (2004). A Complete Guide to the Snakes of Southern Africa. Second Edition. Struik.
  13. ↑ 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. Bibcode:2000Txcn...38.1613K. doi:10.1016/S0041-0101(00)00089-1. PMID   10775761.
  14. ↑ "LD50 for various snakes". seanthomas.net. Retrieved 2017-11-14.
  15. ↑ Mackessy, Stephen P. (2002). "Biochemistry and Pharmacology of Colubrid Snake Venoms". Journal of Toxicology – Toxin Reviews21 (1&2): 52. online PDF Archived 2010-06-02 at the Wayback Machine
  16. ↑ Young, R. A. (1996). "IN VITRO ACTIVITY OF DUVERNOY'S GLAND SECRETIONS FROM THE AFRICAN BOOMSLANG, Dispholidus typus, ON NERVE-MUSCLE PREPARATIONS". Journal of Venomous Animals and Toxins. 2 (1): 52–58. doi: 10.1590/S0104-79301996000100007 .
  17. ↑ Pla, Davinia; Sanz, Libia; Whiteley, Gareth; Wagstaff, Simon C.; Harrison, Robert A.; Casewell, Nicholas R.; Calvete, Juan J. (April 2017). "What killed Karl Patterson Schmidt? Combined venom gland transcriptomic, venomic and antivenomic analysis of the South African green tree snake (the boomslang), Dispholidus typus". Biochimica et Biophysica Acta (BBA) - General Subjects. 1861 (4): 814–823. doi:10.1016/j.bbagen.2017.01.020. ISSN   0006-3002. PMC   5335903 . PMID   28130154.
  18. ↑ Mazza, Giuseppe (2011-04-27). "Dispholidus typus". Monaco Nature Encyclopedia. Retrieved 2022-07-09.
  19. ↑ "Diary of A Snakebite Death". YouTube . 27 October 2015.
  20. ↑ "The Boomslang Snake Of Africa". www.reptilesmagazine.com. 21 February 2012. Retrieved 2017-11-14.
  21. ↑ Pope, Clifford H (1958). "Fatal Bite of Captive African Rear-Fanged Snake (Dispholidus)". Copeia. 1958 (4): 280–282. doi:10.2307/1439959. JSTOR   1439959.
  22. ↑ Smith, Charles H. "Chrono-Biographical Sketch: Karl P. Schmidt". Some Biogeographers, Evolutionists and Ecologists. Retrieved 9 September 2014.
  23. ↑ Bücherl W, Buckley E, Deulofeu V (editors) (1968). Venomous Animals and Their Venoms, Volume I: Venomous Vertebrates. Academic Press. p. 484.
  24. ↑ "About Us – South African Vaccine Producers (SAVP)". Archived from the original on 11 April 2021. Retrieved 3 November 2015.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.