Checkered Keelback ( Xenochrophis piscator Schneider, 1799 )

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Name
Scientific Name: 
Xenochrophis piscator (Schneider, 1799)
Regional Names: 
English: 
Asiatic Water Snake
Kannada: 
ನೀರು ಹಾವು, ಬೆನ್ನೇಣು ಹಾವು
Hindi: 
Paani wala saap
Marathi: 
Divad
Malayalam: 
പുളവന്‍, നീര്‍ക്കോലി
Gujarati: 
ડેડું
Photographs: 
Distribution: 
Found in all over the country including North-east states. This is the most widely distributed species of the genus Xenochrophis.
Venom Type: 
N/A
Family: 
Characteristics for identification: 

Morphologically it is variable in colors and somewhat in patterns also. Overall it can be identified by carefully checking blackish patched dorsal surface on brown, greenish or yellow ground color.

Description: 

Average length- 90cm.
Maximum length- 175cm.

Dorsal -
Body stout with keeled scales on top and smoother on side rows. Scales have 2-4 different colors in a single specimen, generally dark olive green dominant with blackish, brownish, reddish and yellowish patches in more or less amount. Specimen from Maharastra have greyish-black color dominant over light colours. Juveniles have clear olive green color with black patches and two yellow colour lines in top scales.

Ventral -
Belly usually yellowish-white or white mixed with red or green (rarely). Subcaudal scales paired in a zig-zag manner, their color is similar to ventral scales but sometimes can be darker than ventrals.

Head -
Head triangular with smooth and shiny scales; broader than neck. Color shiny olive green or brownish mostly. Two black streaks starts from eyes and ends to the posterior of lip, the color of area between these streaks is usually lighter than rest of head part. Two yellow-black patches present on inner side of parietal scales and very close to each other; may be absent in adults. Eyes have rounded pupil; tongue color purplish-black.

Tail -
Tail also covered with highly keeled scales. Normal as typical range and ends with pointed tip. Color almost same like rest of the dorsal body but usually without any dark markings.

Scalation
Head: 
Internasals distinctly narrowed anteriorly; supralabial 9; 4th & 5th touches eyes while 6th supralabial is excluded by 3rd postocular; preocular 1; single well defined loreal; postocular 3; temporal 2+2 or 2+3. Dorsal: Keeled scales in 19:19:17 rows.
Dorsal: 
Keeled scales in 19:19:17 rows.
Ventral: 
122-158; anal mostly divided.
Sub Caudal: 
(60) 70-97; paired.
Habitat: 
Lives around any type of water body including lakes, river, pond, sewer line, logged water in agricultural lands, wells; can survive in moist surrounding without any water supply. Activity both diurnal and nocturnal. Behavior very alert, active and aggressive. On threatening rise its forebody and stretch it in fake hood manner. Gives painful bite by deep wounds. Reproduction - Mating is from winter starting to middle of summer. Female lay up to 90 eggs in dry and moist place. Maximum hatchlings observe during late June to July.
Natural History: 
Checkered Keelback is a species capable in showing activity anytime. However prone activity is seen during early morning and evening. Locomotion fast and jumpy when threatened. Behavior alert, aggressive and very quick to respond. To show alertness and aggression it inflates much of fore body to show false hood. On threatening always try to escape first by creeping in jumpy manner. In cornered or handled position it bites in chew manner which is always injurious. Oviparous. Mating occurs from winters to summer. Female lays up to 90 eggs. New born seen from May to mid monsoon.
Diet: 
Feeds mainly on fishes, frogs and toads. Also feeds on rodents, other snakes, rejected meat pieces etc. Juveniles feed on tadpoles also. Majorly fish feeder (77%). X. piscator showed significantly higher feeding frequencies in males and less in females than expected.
Threats: 
Major threats are road kills and intentional killing by people because of its wide range of colors and patterns which makes its identification tough sometimes. Due to its aggressive behavior it can be confused with Cobra. As it is well settled in urban areas, habitat destruction doesn't seem to be a serious threat for this species. In many parts of its range it is consumed by few communities.
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