Bungarus

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Bungarus
Davidraju IMG 7334.jpg
Bungarus fasciatus (banded krait), the largest species of krait
Scientific classification e
: [[Template:Taxonomy/Bungarus]]
Daudin, 1803
Type species
Bungarus annularis
Daudin, 1803[1]
Synonyms[1]

Bungarus is a genus of venomous elapid snakes, the kraits ("krait" is pronounced /krt/, rhyming with "kite"),[2][3] found in South and Southeast Asia. The genus Bungarus has 16 species.

Distribution[edit]

Kraits are found in tropical and subtropical South and Southeast Asia and Indochina, ranging in the west from Iran, east through the Indian subcontinent (including Bangladesh, Nepal, Pakistan, & Sri Lanka) and into Southeast Asia (including the island of Borneo, Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Papua New Guinea, the Philippines, Thailand and Vietnam).[4]

Description[edit]

Kraits usually range between 1.0 and 1.5 m (3 ft 3 in and 4 ft 11 in) in total length (including tail), although specimens as large as 2.0 m (6 ft 7 in) have been observed. The banded krait (B. fasciatus) may grow as large as 2.125 m (6 ft 11.7 in).[5] Most species of kraits are covered in smooth, glossy scales arranged in bold, striped patterns of alternating black and light-colored areas. This may serve as aposematic colouration in its habitat of grassland and scrub jungle. The scales along the dorsal ridge of the back are hexagonal. The head is slender, and the eyes have round pupils. Kraits have pronounced dorsolateral flattening, which causes them to be triangular in cross section.

Diet and behavior[edit]

Kraits are ophiophagous, preying primarily upon other snakes (including venomous varieties) and are cannibalistic, feeding on other kraits. They also eat mice and small lizards.[6]

All kraits are nocturnal. They are more docile during the daylight; at night, they become very active, but are not very aggressive even when provoked. They are actually rather timid, and often hide their heads within their coiled bodies for protection. When in this posture, they sometimes whip their tails around as a type of distraction.[7]

Reproduction[edit]

Kraits are oviparous. The female lays a clutch of 12 to 14 eggs in piles of leaf litter, and stays with them until they hatch.

Venom[edit]

Bungarus contains some species that are among the most venomous land snakes in the world, to mice, based on their Template:LD50.[8][verification needed] They have a highly potent, neurotoxic venom, which can induce muscle paralysis. Clinically, their venom contains mostly presynaptic neurotoxins, which affect the ability of neuron endings to properly release a chemical communication mechanism to the next neuron. Following envenomation with bungarotoxins, transmitter release is initially blocked (leading to a brief paralysis), followed by a period of massive overexcitation (cramps, tremors, spasms), which finally tapers off to paralysis.

These phases of envenomation may or may not be experienced in all parts of the body; they may or may not be experienced simultaneously. The severity of the bite itself and the actual dosage of venom delivered plays a role in the intensity of symptoms. As kraits are mainly nocturnal, encounters with humans are rare during the daytime. Bites mainly occur after sunset, and are often (initially) painless; thus, a bite may go unnoticed if the victim is sleeping or otherwise does not see or notice the krait, further prolonging envenomation damage within the body. Still—whenever possible—medical treatment should be sought posthaste, as a bite from a krait is considered potentially life-threatening. All venomous snake bites must be taken seriously as an immediate medical emergency.

Typically, victims will start to notice severe abdominal cramps accompanied by progressive muscular paralysis, and frequently starting with ptosis. As no local symptoms are usually seen, a patient should be carefully observed for tell-tale signs of paralysis (e.g. the onset of bilateral ptosis, diplopia, and dysphagia), and subsequently treated (as quickly as possible) with antivenom. Frequently, little or no pain occurs at the site of a krait bite, which can provide false reassurance to the victim. The major medical difficulty of envenomated patients is the lack of medical resources (especially intubation supplies and mechanical ventilators in rural hospitals) and potential for ineffectiveness by the antivenom.

Upon arriving at a healthcare facility, support must be provided until the venom has metabolised and the victim can breathe unaided, especially if no species-specific antivenom is available. Given that the toxins alter acetylcholine transmission—which causes the paralysis—some patients have been successfully treated with cholinesterase inhibitors, such as physostigmine or neostigmine, but success is variable and may be species-dependent, as well. If death occurs, it typically takes place about 6-12 hours after the krait bite, but can be significantly delayed. The usual cause of death in that situation is respiratory failuresuffocation by complete paralysis of the diaphragm. Even if patients make it to a hospital, subsequently entering a permanent coma (and even brain death from hypoxia) may occur, given the potential for long transport times to get medical care, in some regions.

Mortality rates caused by bites from the members of this genus vary by species; according to University of Adelaide Department of Toxicology, bites from the banded krait have a mortality rate of 1–10% in untreated humans,[9] while that of the common krait is 70–80%.[10] In common with those of all other venomous snakes, the death time and fatality rate resulting from bites of kraits depend on numerous factors, such as the venom yield and the health status of the victim.

Polyvalent elapid antivenom is effective in neutralizing of the venoms of B. candidus and B. flaviceps, and rather effective for B. fasciatus, and the monovalent B. fasciatus antivenom is also moderately effective.[11]

Species[edit]

Image Species Authority Subsp.* Common name Geographic range
Andaman Krait.jpg Bungarus andamanensis Biswas & Sanyal, 1978 0 South Andaman krait India (Andaman Island)
Bungarus bungaroides.jpg Bungarus bungaroides (Cantor, 1839) 0 Northeastern hill krait Myanmar, India (Assam, Cachar, Sikkim), Nepal, Vietnam
Coomon Krait.jpg Bungarus caeruleusT (Schneider, 1801) 0 Common krait, Indian krait Afghanistan, Pakistan, India (Bengal, Maharashtra, Karnataka), Sri Lanka, Bangladesh, Nepal
Bungar candi 120608-0343 krw.jpg Bungarus candidus (Linnaeus, 1758) 0 Blue krait, Malayan krait Cambodia, Indonesia (Java, Sumatra, Bali, Sulawesi), Malaysia (Malaya), Singapore, Thailand, Vietnam
The Ceylon krait or Sri Lankan krait (Bungarus ceylonicus) is a species of venomous snake endemic to the island Sri Lanka.jpg Bungarus ceylonicus Günther, 1864 1 Ceylon krait, Sri Lankan krait Sri Lanka
Banded Krait, Bungarus fasciatus (24025894235).jpg Bungarus fasciatus (Schneider, 1801) 0 Banded krait Bangladesh, Brunei, Myanmar, Cambodia, south China (incl. Hong Kong, Hainan), north-east India, Bhutan, Nepal, Indonesia (Sumatra, Java, Borneo), Laos, Macau; Malaysia (Malaya and East Malaysia), Singapore, Thailand and Vietnam.
Red-headed Krait.jpg Bungarus flaviceps (Reinhardt, 1843) 1 Red-headed krait South Thailand, South Myanmar, Cambodia, Vietnam, Malaysian Peninsula, Pulau Tioman, Indonesia (Bangka, Sumatra, Java, Billiton, Borneo)
Bungarus lividus, Lesser Black Krait at Jalpaiguri, India.jpg Bungarus lividus Cantor, 1839 0 Lesser black krait India, Bangladesh, Nepal
Bungarus multicinctus 125204318.jpg Bungarus magnimaculatus Wall & Evans, 1901 0 Burmese krait Myanmar
Bungarus multicinctus Blyth, 1861 1 Many-banded krait Taiwan, south China (Hong Kong, Hainan), Myanmar, Laos, northern Vietnam, and Thailand
Bungarus niger 83013559.jpg Bungarus niger Wall, 1908 0 Black krait, Greater black krait India (Assam, Sikkim), Nepal, Bangladesh, Bhutan
Bungarus persicus Abtin, Nilson, Mobaraki, Hosseini & Dehgannejhad, 2014 0 Persian krait, Iranian krait Iran
Sind Krait.jpg Bungarus sindanus Boulenger, 1897 2 Sind krait Southeast Pakistan, India
Bungarus slowinskii[12] Kuch, Kizirian, Q. Nguyen, Lawson, Donnelly & Mebs, 2005 0 Red River krait Northern Vietnam, Thailand, Laos, Cambodia.
Paratype of Bungarus suzhenae in life - Oo 521379.jpg Bungarus suzhenae Chen, Shi, S. C., Vogel, Ding, & Shi, 2021 0 Suzhen's krait China (Yunnan), Myanmar (Kachin State)
Bungarus Walli Wall by Ganesh Sah.jpg Bungarus walli Wall, 1907 0 Wall's krait India (Uttar Pradesh), Nepal, Bangladesh

*) Not including the nominate subspecies (typical form).
T) Type species

See also[edit]

References[edit]

  1. 1.0 1.1 "Bungarus". RepFocus - A Survey of the Reptiles of the World. Rune Midtgaard. Retrieved 21 July 2021.
  2. "krait, n." Oxford English Dictionary Online. Oxford University Press (accessed June 30, 2014).
  3. "krait". American Heritage Dictionary. Accessed June 30, 2014.
  4. SurvivalIQ: Krait
  5. Smith, Malcolm A. (1943). The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-region. Reptilia and Amphibia. Vol. III.—Serpentes. London: Secretary of State for India. (Taylor and Francis, printers). xii + 583 pp. (Bungarus, genus and species, pp. 407-418).
  6. Richard Mastenbroek's Elapid Pages: Kraits (Bungarus ssp.)
  7. "Living in Indonesia:Banded Krait". Archived from the original on 2006-05-08. Retrieved 2006-06-01.
  8. Whitaker, Romulus; Captain, Ashok (2004). Snakes of India, The Field Guide. Chennai: Draco Books. p. 495. ISBN 81-901873-0-9.
  9. "Bungarus fasciatus ". WCH Clinical Toxinology Resources.
  10. "Bungarus caeruleus ". WCH Clinical Toxinology Resources. Archived from the original on 2016-10-16. Retrieved 2011-11-10.
  11. Nget Hong Tan. "Antivenoms against Malaysian poisonous snakes". University of Malaya. Archived from the original on 2009-02-28. Retrieved 2009-09-23.
  12. Kuch, Ulrich; Kizirian, David; Nguyen, Quang Truong; Lawson, Robin; Donnelly, Maureen A.; Mebs, Dietrich (2005). "A new species of krait (Squamata: Elapidae) from the Red River System of Northern Vietnam". Copeia 2005 (4): 818-833. (Bungarus slowinskii, new species).

Further reading[edit]

  • 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 Bungarus, pp. 365-366, Figure 26, three views of skull).
  • Daudin FM (1803). Histoire Naturelle, Génerale et Particulière des Reptiles; Ouvrage faisant suite aux Œuvres de Leclerc de Buffon, et partie de Cours complete d'Histoire naturelle rédigé par C.S. Sonnini, membre de plusieurs Sociétés savantes. Tome cinquième [Volume 5]. Paris: F. Dufart. 365 pp. (Bungarus, new genus, p. 263). (in French).

External links[edit]

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