Silent Predator - The Krait of India

The krait, often referred to as the “silent predator,” is one of India’s most dangerous and enigmatic snakes. Known for its potent venom and elusive nature, the krait commands both fear and fascination. This nocturnal hunter, typically found in rural areas, is responsible for a significant number of snakebite fatalities in the country. Despite its deadly reputation, the krait is a creature of remarkable adaptability and survival, playing a crucial role in the ecosystem.

Globally, there is a dispute regarding the number of species and subspecies of genus Bungarus. According to the reptile database there are around 21 recognized species of kraits (http://reptile-database.reptarium.cz/advanced_search?genus=Bungarus&exact=genus&submit=Search) ,with India being home to nine of them but on the other hand according to Reptile focus (https://repfocus.dk/Bungarus.html) there are 18 species found worldwide, but the species in India remains the same in both the cases. Kraits are found across a wide range, inhabiting tropical and subtropical regions of South and Southeast Asia and Indochina. Their distribution stretches from Iran in the west, across the Indian subcontinent—including Bangladesh, Nepal, Pakistan, and Sri Lanka—and extends eastward into Southeast Asia, encompassing countries like Myanmar, Thailand, Vietnam, Cambodia, Laos, Malaysia, Indonesia, the Philippines, and even the island of Borneo.

In India, kraits are widespread, found in various habitats ranging from the plains to the foothills of the Himalayas. They thrive in diverse environments, including dry scrublands, moist forests, and areas near human settlements, where they often take shelter in rodent burrows, termite mounds, and under piles of debris.

Understanding the krait’s behavior, habitat, and impact is essential not only for public safety but also for the conservation of this intriguing species.

Table of Contents

How they got their name

The name “krait” has its origins in the Hindi word “karait,” which means black, a fitting description for the predominantly black common Indian krait (Bungarus caeruleus) commonly found in the Hindi heartland of Central India. On the other hand, the genus name Bungarus is derived from the Telugu word “Bungarum,” meaning gold. This name reflects the appearance of the banded krait (Bungarus fasciatus), which is characterized by its distinctive gold bands. The duality in these names—one meaning black and the other gold—highlights the regional diversity and the characteristics of the species that were first encountered and described in different parts of India. The common name “krait” likely originated in regions like Madhya Pradesh and parts of Uttar Pradesh, where the black Indian krait is a familiar presence.

Habit and habitat of Krait

The kraits are fascinating and highly venomous snake native to India. Kraits are predominantly nocturnal creatures, meaning they are most active at night, and it is during these hours that they forage slowly on the ground and among leaf litter. Their diet mainly consists of other snakes, including their kind, making them Ophiophagus. However, they are also known to prey on small rodents and lizards. Juvenile kraits, though less understood, are believed to feed on insects, worm snakes, and hatchling lizards.

In terms of reproduction, kraits are oviparous, meaning they lay eggs. In South India, mating occurs in December, with females laying between 5 to 15 eggs in February. These eggs are often deposited in burrows or piles of leaf litter, and the female usually stays with them until they hatch in April. The hatchlings, tiny and as thin as a ballpoint pen refill, are vividly marked, often with a collar around their necks that fades as they mature.

Kraits are known for their generally non-aggressive demeanor. When threatened, they usually prefer to flee, but if cornered, they will coil up with their head tucked underneath their body for protection. Although they are typically docile, some species can thrash violently when disturbed. Despite their timid nature, kraits are responsible for a significant number of snakebite fatalities in India due to their highly toxic venom. Their bites are often painless and occur mostly at night, which is why they are considered among the most medically important snakes in the country.

The habitat of kraits in India is diverse, ranging from forests and scrublands to agricultural fields and areas near human settlements. They are seldom encountered during the day, as they tend to be more alert and active at night. These snakes play a crucial role in the ecosystem by controlling the population of other snakes and small vertebrates. However, despite their importance and the fear they inspire, much about their behavior and biology remains unknown, making them one of the more mysterious inhabitants of the Indian subcontinent.

Venom & Toxicity

Kraits are among the most venomous snakes in the world, with the common krait (*Bungarus caeruleus*) being one of the most dangerous in India. As part of the “Big Four”—the snakes responsible for the majority of snakebite fatalities in India, Bangladesh, and Nepal—the krait’s venom is both potent and deadly. Kraits belong to the Elapidae family, which also includes cobras, coral snakes, and sea snakes. Members of this family are characterized by their relatively short, fixed front fangs and sleek, elongated bodies with smooth scales.

The venom of kraits is primarily neurotoxic, meaning it affects the nervous system, and it is especially potent among land snakes. The neurotoxins in krait venom, particularly the presynaptic neurotoxins, block the transmission of signals from nerve endings to muscles. This disruption can lead to muscle paralysis, including paralysis of the diaphragm, which is crucial for breathing. As the venom takes effect, victims may experience difficulty breathing, muscle cramps, tremors, and eventually, total paralysis. This can lead to asphyxia if not treated promptly, as the diaphragm ceases to function, making it impossible to breathe without assistance.

Interestingly, krait bites are often painless, and the snake’s tiny fangs may leave little to no visible mark, which can delay a victim’s response to seek medical help. This, combined with the belief in some parts of India that kraits kill by coiling around their victims and “sucking the breath out of them,” adds to the snake’s fearsome reputation. However, these are myths; the real danger lies in the venom’s ability to shut down the nervous system.

While the common krait’s venom is extremely potent, the Sind krait (*Bungarus sindanus*) has been found to possess venom that is even more toxic, potentially five times stronger. Despite this, the common krait’s venom remains deadly and should never be underestimated. It lacks cytotoxic (cell-damaging) or haematotoxic (blood-affecting) components, meaning its primary danger lies in its neurotoxic effects.

Fortunately, with timely medical intervention, including respiratory support such as a ventilator, many victims of krait bites can recover fully. The venom does not affect the heart directly, so as long as breathing is maintained, the heart can continue to function until the venom’s effects are managed. However, the speed at which krait venom acts makes rapid medical response critical. Contrary to some myths, a krait bite does not kill within minutes, but the urgency for treatment remains high as symptoms can progress quickly.

Krait Species found in India

Common Krait (Bungarus caeruleus)

The common krait, also known as the Bengal krait, is a highly venomous snake belonging to the Elapidae family. Native to the Indian subcontinent, this species is one of the “Big Four” snakes in India, Pakistan, and Bangladesh, responsible for a significant number of snakebite fatalities in these regions.

The common krait is widespread across India and is particularly feared due to its potent venom and its habit of frequenting human habitations. The species was first described in 1801 by the German naturalist Johann Schneider in Vishakapatnam, Andhra Pradesh. The name caeruleus refers to the dark coloration of the snake, typically black, which is its most common morph.

These kraits are nocturnal hunters, known for their activity at night while remaining relatively quiet and hidden during the day. They can be found in a variety of environments, including termite hills, burrows, garden pots, and even urban construction sites. Remarkably, common kraits are cannibalistic and will consume their own kind in addition to preying on other snakes, mice, lizards, and frogs.

The common krait’s secretive nature and potent venom make it one of the most dangerous snakes in its range, contributing to its fearsome reputation throughout South Asia.

Yingjiang Krait (Bungarus suzhenae)

The Yingjiang krait, also known as Suzhen’s krait, is a newly described species of krait that was officially recognized in 2021. This species is named after Bai Suzhen, the snake goddess from the Chinese legend “Legend of the White Snake,” who is revered as a deity of medicine, healing, and true love.

The Yingjiang krait is found in the monsoon forests of southwestern China and northern Myanmar, particularly in rice fields and near streams at elevations ranging from 800 to 1,560 meters (2,600 to 5,100 feet) above sea level. The snake’s discovery is closely associated with the tragic death of renowned herpetologist Joseph B. Slowinski in 2001, who was bitten by what was initially believed to be an immature black-and-white banded krait while leading an expedition in northern Myanmar. The true identity of the snake as a new species was only revealed after samples were collected and examined between 2016 and 2019 in Yingjiang County, Yunnan Province, China.

The Yingjiang krait is considered highly dangerous due to the potent venom typical of kraits, making it a potentially lethal species. Understanding this species is crucial for medical science and herpetology, as it can help prevent future fatalities and improve treatment for krait bites.

Greater Black Krait (Bungarus niger )

The Greater Black Krait is a rare and venomous snake species endemic to South Asia. It inhabits the edges of villages and forests in the Eastern Himalayas, with a distribution that spans from Pithoragarh in Uttarakhand to the Himalayan foothills and across the northeastern regions of the Indian subcontinent, including parts of Bangladesh, Bhutan, and Nepal.

First described in 1908 by the Ceylon-born herpetologist Frank Wall, based on specimens from Darjeeling, the name *niger* refers to the snake’s distinctive overall black coloration, which is devoid of any bands. The Greater Black Krait is a medium-sized snake, typically growing up to 130 cm in length. Its body is characterized by a glossy, patternless bluish-black, dark chocolate brown, or dark grey coloration, while the underside is white or off-white, with the outer edges of the ventral scales shaded with grey. The head of the Greater Black Krait is moderately sized, slightly broader than the neck, and features a rounded snout. Like other kraits, its eyes appear entirely black.

This species is found in a variety of habitats, ranging from mangrove swamps to inhabited villages and montane forests up to elevations of 1,500 meters (4,900 feet) above sea level in the Himalayan foothills. Although it is relatively rare, the Greater Black Krait’s presence in these diverse environments highlights its adaptability. However, due to its potent venom and medical significance, it is a species that commands both caution and respect.

Lesser Black Krait (Bungarus lividus)

The Lesser Black Krait is an uncommon but medically significant species of krait found in the northeastern region of the Indian subcontinent. This venomous snake was first described in 1839 by Theodore Cantor, with the initial specimen collected from Assam. The name lividus refers to the snake’s distinctive bluish lead metallic color.

Morphologically, the Lesser Black Krait closely resembles the Greater Black Krait. Both species have a uniform, pattern less black body with a yellowish underside. However, they can be differentiated by the shape and size of their vertebral scales. In the Lesser Black Krait, these scales are not as distinct from the adjacent scales and are significantly narrower compared to most other krait species. In contrast, the vertebral scales of the Greater Black Krait are significantly larger than the adjacent scales and have a hexagonal shape.

The Lesser Black Krait is a medium-sized snake that can grow up to 102 cm in length. Its entire body is glossy bluish-black, dark chocolate brown, or dark grey, while its underside is typically white or off-white with the outer edges of the ventral scales shaded with grey. The snake’s head is moderate in size, slightly broader than the neck, with a rounded snout. Like other kraits, its eyes appear entirely black.

Despite its unassuming appearance, the bite of the Lesser Black Krait is highly venomous and can be fatal, making it a species of significant medical importance in its range.

Banded Krait (Bungarus fasciatus)

The banded krait is a highly venomous snake belonging to the elapid family, endemic to Asia. Its range extends from the Indian subcontinent through Southeast Asia to southern China. Notably, it is the longest of all krait species, with some individuals reaching lengths of up to 2.25 meters (7 feet 5 inches), although more commonly they are around 1.8 meters (5 feet 11 inches) long.

Easily identifiable by its striking gold and black crossbands, the banded krait is distinguished by a broad, depressed head that is not distinct from its neck, and black eyes. The snake also features arrowhead-like yellow markings on its otherwise black head, with yellow coloring on its lips, lores, chin, and throat. Its tail is relatively short, constituting about one-tenth of the snake’s overall length.

Despite its potent neurotoxic venom, which can be lethal to humans, the banded krait is generally considered to be mild-mannered and docile. Its venom is less toxic compared to other kraits based on murine LD50 experiments, but due to the snake’s large size, the venom yield is significantly higher. This species is nocturnal and typically feeds on other snakes, as well as frogs, lizards, and small mammals. Bites from the banded krait are rare, as it is not aggressive and tends to avoid confrontation.

The banded krait’s distinctive appearance and relatively mild temperament have made it a well-recognized species throughout its range. However, due to the potentially lethal nature of its venom, it remains a species that should be approached with caution.

Andaman Krait (Bungarus andamanensis)

The Andaman krait is a rare and narrowly distributed species of krait, endemic to the Andaman Islands. First described in 1978 by S. Biswas and D.P. Sanyal of the Zoological Survey of India, this species is unique to the Andaman Islands and is not found in the nearby Nicobar Islands.

Morphologically, the Andaman krait is easily recognizable by its glossy dark brown or black dorsal body, which is marked with distinct yellowish bands. Despite its striking appearance, very little is known about the venom potency of this species. Although its venom has not been extensively studied, it is considered potentially dangerous and should not be taken lightly.

The Andaman krait is most commonly seen near roadside ditches during the monsoon season. However, due to the limited information available on this species, including its venom’s effects and behavior, it remains a mysterious and poorly understood member of the krait family. No fatalities have been reported from its bites, but its presence in the Andaman Islands contributes to the region’s rich biodiversity and highlights the need for further research into its ecology and venom.

Wall’s Krait (Bungarus walli)

Wall’s Krait is a venomous elapid snake found in northern India, Bangladesh, Nepal, and Bhutan. Initially considered a subspecies of the Sind krait (*Bungarus sindanus*), it is now recognized as a distinct species. Wall’s krait is a medium-sized snake that can grow up to 165 cm in length.

This species is easily identifiable by its glossy bluish-black or dark chocolate brown body, which is adorned with densely arranged milky white bands throughout its length. Notably, Bungarus walli has more bands than any other Indian krait. The snake’s underside is white in young individuals and becomes off-white or yellowish white with greyish edges on the ventral scales as it matures. The head is moderate in size, slightly broader than the neck, and rounded at the front. Like all kraits, it has small, entirely black eyes.

Wall’s krait inhabits a variety of environments, including forests, agricultural fields, and both rural and urban areas. Despite its potent venom, the species is locally common within its range. Its distinctive banding pattern and adaptability to different habitats make it a notable species among the kraits of the Indian subcontinent.

Eastern Himalayan Krait (Bungarus bungaroides)

The Himalayan krait, also known as the northeastern hill krait, is a venomous snake found in the mountainous regions of India and neighboring countries. This species inhabits areas at elevations of about 2,400 meters and is distributed across parts of Assam, Meghalaya, Sikkim, Arunachal Pradesh, Nagaland, and West Bengal in India, as well as in Myanmar, Bhutan, Vietnam, China, Nepal, and Tibet.

First described in 1839 by Theodore Cantor, a Danish naturalist working with the British East India Company, the Himalayan krait was initially discovered in Cherrapunji, Meghalaya. It is a medium-sized snake, typically growing up to 140 cm in length. The snake’s body is characterized by a glossy bluish-black or blackish-brown coloration, adorned with fine milky bands. The anterior body bands are obliquely arranged, giving the snake a distinct pattern. In younger individuals, the head is marked with fine lines across the snout and features an arrow-like mark on the top of the head that extends down to the neck. The underside of the snake is grey-black, banded with white due to the extension of the dorsal body bands. The head of the Himalayan krait is not much broader than its neck, and it has medium-sized, entirely black eyes.

Sind Krait (Bungarus sindanus)

The Sind krait is a venomous species of krait found across India, Pakistan, and Afghanistan. In India, it has been specifically recorded in the states of Gujarat, Maharashtra, Punjab, and Rajasthan. This species is often mistaken for the common krait due to their similar appearance.

Like other Kraits, Sind kraits are also nocturnal, which increases the likelihood of accidental encounters with humans and domestic animals. These snakes rely on their camouflage and coloration to blend into their surroundings, often remaining still when threatened. This behavior can be so effective that people may unintentionally step on them, leading to bites. Despite their tendency to avoid confrontation, the Sind krait’s venom is highly potent, making it a significant species of medical concern in the regions where it is found.

In conclusion

The kraits of India are among the most enigmatic and deadly snakes in the subcontinent. These nocturnal predators, known for their potent neurotoxic venom, are responsible for a significant number of snakebite fatalities each year, particularly in rural areas where they often come into contact with humans. Despite their deadly reputation, kraits are generally reclusive and avoid confrontation, striking only when threatened or provoked.

The diversity within the krait genus, with species spread across various habitats from the plains to the Himalayas, reflects the adaptability and evolutionary success of these snakes. Each species, from the common krait to the more obscure Andaman and lesser black kraits, plays a crucial role in its ecosystem, often controlling populations of other reptiles and small mammals.

While much is still to be learned about their behavior, venom composition, and ecological roles, the importance of these snakes in both natural and medical contexts cannot be overstated. Continued research and awareness are vital in mitigating the risks they pose to humans while preserving the ecological balance they help maintain in India’s rich biodiversity.