''Craspedocephalus trigonocephalus'', the Sri Lankan pit viper, Ceylon pit viper, Sri Lankan green pitviper or locally, pala polonga, ( si, පළා පොළඟා) is a venomous

pit viper The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . crotaline snakes (from grc, κρόταλον ''krotalon'' castanet), or pit adders, are a subfa ...

species endemic to

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

. No

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

are currently recognized.

Description

''Craspedocephalus trigonocephalus'' is a sexually dimorphic, mid-sized, cylindrical species. These snakes measure at birth, and males grow to a maximum total length of . The neck is distinct from the flattened, triangular head. There is a loreal pit on each side of the head. Mid-sized eyes and a short, rounded, broad

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is c ...

are present. The males are considerably smaller than females, which can grow up to in total length. The ground color of the snake is variable and

cryptic Cryptic may refer to: In science: * Cryptic species complex, a group of species that are very difficult to distinguish from one another * Crypsis, the ability of animals to blend in to avoid observation * Cryptic era, earliest period of the Earth ...

. Typically, it is a green snake with a black variegated pattern, and a black temporal line is usually present. The wet zone snakes have these black patterns more clearly marked. The vertebral area has a tinge of yellow. The tail is black. The ventral scales are light greenish-yellow or may even be grey. Some snakes have only the black temporal line and the black tail, with the rest of the body being green. In addition, males tend to have a blue coloration, whereas the females are predominantly green. These are bulky snakes with

prehensile Prehensility is the quality of an appendage or organ (anatomy), organ that has Adaptation (biology), adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely der ...

, short tails, suiting their arboreal lifestyle. Sri Lanka Green Pit Viper head detail

Reproduction

These are viviparous snakes. About five to 25 young are produced at once.

Scales

These snakes have two or three large supra

ocular scales In scaled reptiles, the ocular scales are those forming the margin of the eye.Wright AH, Wright AA. 1957. ''Handbook of Snakes''. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . The name originates from the term ''oculus'' which ...

, and their

nasal scale In reptiles, the nasal scale refers to the scale that encloses the nostril.Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. . Sometimes this ...

s are partially divided into two or may not be divided. They have three preoculars, two or three postoculars, 9–10

supralabial scale In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scaleWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates ( ...

s, three or four infralabials, and 142–160

ventrals In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

; The anal scale is not divided; their 53–69 subcaudals are divided. At midbody, the 17–19 rows of dorsal scales may or may not have keels. Most head shields are small and smooth.

Common names

Common names include: Sri Lankan green pit viper,Gumprecht A, Tillack F, Orlov NL,

Captain A Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...

, Ryabov S. 2004. ''Asian Pitvipers''. Geitje Books. Berlin. 1st Edition. 368 pp. . Sri Lankan pit viper,Mehrtens JM. 1987. ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . ''pala polonga'' (පළා පොළඟා), and green pit viper.

Geographic range

It is an endemic species to Sri Lanka and widely distributed in all three

climatic zone Climate classifications are systems that categorize the world's climates. A climate classification may correlate closely with a biome classification, as climate is a major influence on life in a region. One of the most used is the Köppen climate ...

s of the island, except higher hills and arid zones, while relatively more common in wet zone

grasslands A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natural ...

and rain forest areas and occasionally in

plantations A plantation is an agricultural estate, generally centered on a plantation house, meant for farming that specializes in cash crops, usually mainly planted with a single crop, with perhaps ancillary areas for vegetables for eating and so on. The ...

of cardamom,

cocoa Cocoa may refer to: Chocolate * Chocolate * ''Theobroma cacao'', the cocoa tree * Cocoa bean, seed of ''Theobroma cacao'' * Chocolate liquor, or cocoa liquor, pure, liquid chocolate extracted from the cocoa bean, including both cocoa butter and ...

, coffee, and tea, from the lower altitudes from .de Silva, 1980 The type locality given is "l'île S.-Eustache" (Sri Lanka).

Behavior

It is arboreal and

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

, occasionally descending to the ground in search of food such as lizards, frogs, small mammals, and birds. This sluggish

is usually encountered on low shrubs during morning hours, but it mostly occupies in grasslands and rain forests. In mornings, it is seen to stay on top of trees to obtain sun rays to heat its body. It uses its tail to hold on to a tree branch. This is not a particularly defensive species, but if agitated, it will vibrate its tail tip, form a sinuous loop with the fore body, and lash and attempt to bite, seldom with a hissing sound. It produces live young mostly during June and July.

Venom

The venom is primarily haemotoxic, with victims experiencing severe pain and swelling of the bitten area, oedema and

blister A blister is a small pocket of body fluid (lymph, serum, plasma, blood, or pus) within the upper layers of the skin, usually caused by forceful rubbing (friction), burning, freezing, chemical exposure or infection. Most blisters are filled wi ...

s, and localised tissue

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

; the pain of the wound may last for a few days.

Ptosis Ptosis (from the Greek: πτῶσις 'falling', 'a fall', 'dropped') refers to droopiness or abnormal downward displacement of a body part or organ. Particular cases include: * Ptosis (eyelid) * Ptosis (chin) * Ptosis (breasts) * Visceroptosis, ...

and

lymphadenopathy Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammatory type (the most common type) is lymphadenitis, producing swollen or enlarged lymph nodes. In cli ...

takes place. Also in some victims, polyuric renal failure and cardiac electrophysiological dysfunction occur, but fatalities have not been reported.