Ancistrodon hypnale

Ancistrodon hypnale, commonly known as the Hump-nosed pit viper or the Sri Lankan pit viper, is a venomous snake species found primarily in Sri Lanka and parts of southern India. It belongs to the family Viperidae and is known for its distinctive hump-like nose scale, which gives it its common name. This snake is considered medically significant due to its venomous bite, which can cause a range of symptoms and potentially be fatal if left untreated. 

DIAGNOSTIC CHARACTERES

Hump-like nose scale:

One of the most distinctive features of this species is the presence of a prominent, hump-like scale on its nose. This specialized scale gives it its common name, the Hump-nosed pit viper.

Head shape:

The snake has a triangular-shaped head, which is broader than its neck. This characteristic head shape is common among venomous snakes.

Body size and shape:

The Hump-nosed pit viper is a relatively small snake, with adults typically reaching lengths of about 60-70 centimeters (24-28 inches). It has a stout and robust body with a relatively short tail.

Coloration and patterns:

The snake's coloration can vary, but it often has a green or brown body with darker markings. These markings may be in the form of blotches, spots, or crossbands. The coloration and patterns provide effective camouflage in its natural habitat.

Heat-sensing pits:

Like other pit vipers, Ancistrodon hypnale possesses specialized heat-sensing pits located on each side of its head, between the eye and the nostril. These pits allow the snake to detect heat emitted by warm-blooded prey, aiding in hunting.

Fangs:

The snake has long, hollow fangs located in the front of its upper jaw. These fangs are used to inject venom into its prey or in defense if threatened. Fangs are a characteristic feature of venomous snakes.

REPRODUCTION

Sexual Dimorphism:

Like many snake species, Hump-nosed pit vipers exhibit sexual dimorphism, with males and females displaying physical differences. Males are typically smaller in size compared to females and may have slightly different coloration or scale patterns.

Mating:

Pit vipers, including Ancistrodon hypnale, are known to engage in sexual reproduction. During the breeding season, which can vary depending on the geographical location, males actively search for receptive females. They may employ various courtship behaviours, including rubbing their chin or body against the female's body, flicking their tongue, and engaging in "dance-like" movements.

Viviparity:

Ancistrodon hypnale is believed to be viviparous, meaning that the females give birth to live young instead of laying eggs. After successful mating, the female retains the fertilized eggs internally, where they develop and receive nourishment from the mother through a placental connection. This allows for greater protection and development of the offspring compared to oviparous species.

Gestation and Birth:

The gestation period, from fertilization to birth, can vary but is generally several months long. When the time for birth approaches, the female finds a suitable location, such as a crevice or under vegetation, to give birth. Live young, typically 6-20 in number, are born enclosed in thin, membranous sacs that the mother breaks open. The newborns are fully formed and capable of independent survival from birth.

Maternal Care:

Pit vipers, including Ancistrodon hypnale, do not provide any parental care beyond birth. Once the young are born, they are left to fend for themselves and find their own food and shelter.

MORPHOLOGY

Body Shape and Size:

 Ancistrodon hypnale is a relatively small snake, with adult specimens typically reaching lengths of about 60-70 centimeters (24-28 inches). It has a stout and robust body, giving it a compact appearance. The body is cylindrical in shape and tapers towards the tail.

Head:

The snake has a triangular-shaped head that is distinct from its neck. It is broader than the body and has well-defined, rounded snout. The head is covered in small, keeled scales.

Scales:

The body is covered in overlapping scales, which provide protection and aid in movement. These scales are keeled (ridged) and give a rough texture to the snake's skin.

Coloration and Patterns:

The coloration of Ancistrodon hypnale can vary, but it often displays shades of green or brown as a primary body color. The snake may have darker markings, such as blotches, spots, or crossbands, which provide effective camouflage in its natural habitat. The specific coloration and patterns can vary among individuals and populations.

Eyes:

The snake has relatively large eyes with vertical pupils, which are characteristic of pit vipers. The eyes are positioned on the sides of the head, providing a wide field of vision.

Hump-like Nose Scale:

One of the most distinguishing features of Ancistrodon hypnale is the presence of a hump-like scale on its nose, from which it derives its common name, the Hump-nosed pit viper. This specialized scale is located between the nostrils and gives the snake a unique appearance.

Tail:

The tail of Ancistrodon hypnale is relatively short compared to the body length. It tapers gradually and ends in a pointed tip. The tail may have a rattle-like appearance due to the presence of modified scales at the end, but it does not possess a functional rattle like some other venomous snakes.

BEHAVIOUR

Nocturnal and Ambush Predators:

Hump-nosed pit vipers are primarily nocturnal, meaning they are most active during the night. They are ambush predators that rely on camouflage and patience to capture their prey. During the day, they often hide under vegetation, rocks, or in crevices, waiting for unsuspecting prey to pass by.

Feeding:

As ambush predators, Ancistrodon hypnale preys on small vertebrates, including frogs, lizards, and small mammals. They use their venomous bite to immobilize and kill their prey. These snakes possess a unique hunting strategy where they use their specialized tail to lure prey by waving it in a rhythmic motion, mimicking a worm or insect. Once the prey is within striking range, the snake delivers a swift strike and injects venom to subdue it.

Defensive Behavior:

When threatened or cornered, Hump-nosed pit vipers can display defensive behavior. They may raise their head and upper body, flatten their neck to appear larger, and hiss as a warning. These snakes have long, hollow fangs capable of delivering potent venom, and they may bite if they feel threatened or provoked.

Camouflage:

Ancistrodon hypnale relies on its excellent camouflage to blend into its environment. The green or brown body coloration and pattern help them remain hidden among vegetation, making them difficult to spot by both predators and potential prey.

Thermoregulation:

Like many reptiles, Hump-nosed pit vipers engage in thermoregulation to maintain their body temperature. They bask in the sun or move to warmer areas when they need to raise their body temperature, and they seek shade or cooler areas to lower their body temperature when needed.

VENOMOSITY

Ancistrodon hypnale, is a venomous snake species. Its venom is considered to be highly toxic and poses a significant threat to humans if bitten. The venom of Ancistrodon hypnale is primarily hemotoxic, affecting the blood and causing tissue damage. 

GENERAL HABITAT

Ancistrodon hypnale can be found in both lowland and montane rainforests. This species is also known to inhabit dry forests, which are found in areas with lower rainfall and characterized by deciduous trees and shrubs. Also found in scrublands, which are open areas with sparse vegetation consisting of shrubs, bushes, and grasses. These habitats are often found on the edges of forests or in areas with lower rainfall. Hump-nosed pit vipers can sometimes be encountered in human-modified habitats such as plantations, agricultural areas, or residential areas near forested regions.