Common krait | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Serpentes |
Family: | Elapidae |
Genus: | Bungarus |
Species: | B. caeruleus |
Binomial name | |
Bungarus caeruleus (Schneider, 1801) | |
Synonyms | |
Pseudoboa caerulea Schneider, 1801, Bungarus candidus var. Cærulus Boulenger, 1896 Contents |
The common krait (Bungarus caeruleus) is a venomous snake species belonging to the genus Bungarus in the Elapidae family. It is native to the Indian subcontinent and is responsible for the majority of snakebites affecting humans in India, Pakistan, and Bangladesh.
The average length of the common krait is 0.9 m (2 ft 11 in), but it can grow to 1.75 m (5 ft 9 in). [2] Males are longer than females, with proportionately longer tails. The head is flat and the neck is hardly visible. The body is cylindrical, tapering towards the tail. The tail is short and rounded. The eyes are rather small, with rounded pupils, indistinguishable in life. The head shields are normal, with no loreals; four shields occur along the margin of the lower lip; the third and fourth supraoculars touch the eye. The scales are highly polished, in 15–17 rows; the vertebral row is distinctly enlarged and hexagonal. Ventrals number 185–225 and caudals 37–50, and are entirely intact. [3] Their coloration is generally black or bluish-black, with about 40 thin, white crossbars, which may be indistinct or absent anteriorly. Albino specimens can be found, although such cases are extremely rare. The pattern, however, is complete and well-defined in the young, which are marked with conspicuous crossbars even anteriorly; in old individuals, the narrow white lines may be found as a series of connected spots, with a prominent spot on the vertebral region. A white preocular spot may be present; the upper lips and belly are white. [3]
This common krait is distributed from West Bengal to Sindh, throughout South India, and Sri Lanka, at elevations up to about 1,600 m (5,200 ft). [2] It has also been recorded in Afghanistan, Pakistan, Iran, Bangladesh, and Nepal. [4] It lives in a wide variety of habitats, from fields and low scrub jungle to settled areas. It rests in termite mounds, brick piles, rat holes, and even inside houses. [2]
The common krait exhibits a sluggish and generally docile behaviour during the day. It often hides in rodent holes, loose soil, or beneath debris, so is rarely seen. It often rolls its body into a loose, coiled ball, keeping its head well concealed. When in this "balled" condition, the snake allows considerable handling, but overhandling often instigates bites. At night, though, the snake is very active and escapes by hissing loudly, or keeping still, occasionally biting the source of the annoyance.
When agitated, it coils up with its head concealed and body flattened, and makes jerky movements. It may also lift its tail. It is reluctant to bite, but when it does, it typically holds on for a while, which enables it to inject considerable amounts of venom. It may become aggressive at night if threatened, since this is its active time. It is responsible for the second-highest number of snake bites in India for a single species. In Bangladesh, it is responsible for 28% of total snake bites.
The common krait feeds primarily on other snakes, and cannibalises on other kraits, including the young. It also feeds on small mammals such as rats, mice, lizards, and frogs. The young are known to eat arthropods and the blind snakes snakes of the family Typhlopidae.
In mice, the LD50 values of its venom are 0.325 mg/kg subcutaneously, 0.169 mg/kg intravenously, and 0.089 mg/kg intraperitoneally. [5] [6] The average venom yield is 10 mg (0.15 gr) dry weight. [7] The estimated lethal dose for humans is 2–3 mg (0.031–0.046 gr). [8]
The common krait is nocturnal, so seldom encounters humans during daylight; incidents occur mainly at night. Frequently, little or no pain occurs from its bite, which can provide false reassurance to the victim. Typically, victims complain of severe abdominal cramps, accompanied by progressive paralysis. If death occurs, it takes place about 4–8 hours after the krait bite. Cause of death is general respiratory failure, i.e. suffocation. [9] The few symptoms of the bite include tightening of the facial muscles in 1–2 hours of the bite and inability of the bite victim to see or talk, and if left untreated, the patient may die from respiratory paralysis within 4–5 hours. A clinical toxicology study reports an untreated mortality rate of 70-80%. [2]
The king cobra is a species complex of snakes endemic to Asia. With an average of 3.18 to 4 m and a record length of 5.85 m (19.2 ft), it is the world's longest venomous snake and among the heaviest. Under the genus Ophiophagus, it is not phylogenetically a true cobra despite its common name and some resemblance. Spanning from the Indian Subcontinent through Southeastern Asia to Southern China, the king cobra is widely distributed albeit not commonly seen.
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.
Russell's viper is a highly venomous snake in the family Viperidae native to South Asia. It was described in 1797 by George Shaw and Frederick Polydore Nodder. It is named after Patrick Russell. Known for its extremely painful bite, it is considered one of the most dangerous big four snakes in India.
The banded krait is an extremely venomous species of elapids endemic to Asia, from Indian Subcontinent through Southeast Asia to Southern China. With a maximum length exceeding 2 m, it is the longest krait with a distinguishable gold and black pattern. While this species is generally considered timid and docile, resembling other members of the genus, its venom is highly neurotoxic which is potentially lethal to humans. Although toxicity of the banded krait based upon murine LD50 experiments is lower than that of many other kraits, its venom yield is the highest due to its size.
The four venomous snake species responsible for causing the greatest number of medically significant human snake bite cases on the Indian subcontinent are sometimes collectively referred to as the Big Four. They are as follows:
The Indian cobra, also known commonly as the spectacled cobra, Asian cobra, or binocellate cobra, is a species of cobra, a venomous snake in the family Elapidae. The species is native to the Indian subcontinent, and is a member of the "big four" species that are responsible for the most snakebite cases in India.
The greater black krait or black krait, is a species of krait, a venomous snake in the genus Bungarus of the family Elapidae. The species is endemic to South Asia.
The Caspian cobra, also called the Central Asian cobra or Russian cobra, is a species of highly venomous snake in the family Elapidae. The species is endemic to Central Asia. First described by Karl Eichwald, a German physician, in 1831, it was for many years considered to be a subspecies of the Naja naja until genetic analysis revealed it to be a distinct species.
The yellow-lipped sea krait, also known as the banded sea krait or colubrine sea krait, is a species of highly venomous snake found in tropical Indo-Pacific oceanic waters. The snake has distinctive black stripes and a yellow snout, with a paddle-like tail for use in swimming.
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.
Echis is a genus of vipers found in the dry regions of Africa, the Middle East, India, Sri Lanka and Pakistan. They have a characteristic threat display, rubbing sections of their body together to produce a "sizzling" warning sound. The name Echis is the Latin transliteration of the Greek word for "viper" (ἔχις). Like all vipers, they are venomous. Their common name is "saw-scaled vipers" and they include some of the species responsible for causing the most snakebite cases and deaths in the world. Twelve species are currently recognized.
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.
Bungarus candidus, commonly known as the Malayan krait or blue krait, is a highly venomous species of snake. The blue krait is a member of the genus Bungarus and the family Elapidae.
α-Bungarotoxin is one of the bungarotoxins, components of the venom of the elapid Taiwanese banded krait snake. It is a type of α-neurotoxin, a neurotoxic protein that is known to bind competitively and in a relatively irreversible manner to the nicotinic acetylcholine receptor found at the neuromuscular junction, causing paralysis, respiratory failure, and death in the victim. It has also been shown to play an antagonistic role in the binding of the α7 nicotinic acetylcholine receptor in the brain, and as such has numerous applications in neuroscience research.
The many-banded krait, also known as the Taiwanese krait or the Chinese krait, is a highly venomous species of elapid snake found in much of central and southern China and Southeast Asia. The species was first described by the scientist Edward Blyth in 1861. Averaging 1 to 1.5 m in length, it is a black or bluish-black snake with many white bands across its body. The many-banded krait mostly inhabits marshy areas throughout its geographical distribution, though it does occur in other habitat types.
Boiga barnesii is a species of cat snake endemic to Sri Lanka. It is known as Barnes' cat snake in English and panduru mapila-පදුරු මාපිලා in Sinhala. It is a member of the snake family Colubridae. It is distributed in the lowlands and midlands up to approximately 600 m (2,000 ft) above sea level, with known localities include Matale, Kandy, Gannoruwa, Gampola, Ambagamuwa, Balangoda, Labugama and Sinharaja Rain Forest. Barnes' cat snake is mainly a forest-dwelling species but may occasionally be found in human habitats. It is the smallest cat snake in Sri Lanka and grows up to a maximum of about 600 mm (24 in) in snout-vent length. Being a nocturnal and an arboreal hunter, it mainly feeds on agamid lizards and geckos. The day time is usually spent inside a tree hole or a crevice. It’s a very timid and a mildly venomous snake and rarely attempts to bite.
The red-headed krait is a large highly venomous elapid snake with dramatic coloration. The red-headed krait can grow to a length of up to 2.1 metres (7 ft). It lives in lowland rain forest, including those on islands, but it is considered uncommon. It feeds primarily on specific snakes, probably semiaquatic and fossorial snakes. In Southeast Asia, the red-headed krait occurs in Malaysia, Singapore, Thailand and Indonesia (Sumatra), with a subspecies in Borneo. The venom potency is little-studied, as bites from this species are extremely rare.
Bungarus magnimaculatus, also known commonly as the Burmese krait, the spotted krait and the splendid krait, is a species of venomous snake in the family Elapidae. The species is endemic to Myanmar.