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Yellow-spotted Keelback

Xenochrophis flavipunctatus

Yellow-spotted Keelback Xenochrophis flavipunctatus on road

Yellow-spotted Keelback found at dusk near ponds in Payao Province

Yellow-spotted Keelback Xenocropis flavipunctus

Yellow-spotted Keelback at edge of marsh in Prawet

Yellow-spotted Keelback head Xenocropis flavipunctus

Head shot of Yellow-spotted Keelback

Michael Cota Xenochrophis flavipunctatus Pathum Thani

Yellow-spotted Keelback in Pathum Thani (photo by Michael Cota)

Yellow-spotted Keelback Xenocropis flavipunctus Vietnam Alex Krohn 1

Yellow-spotted Keelback trapped in Vietnam (photo by Alex Krohn)

Yellow-spotted Keelback Xenocropis flavipunctus Vietnam Alex Krohn 2

Yellow-spotted Keelback rearing head in Vietnam (photo by Alex Krohn)

Yellow-spotted Keelback Xenocropis flavipunctus Vietnam Alex Krohn

Head shot of Yellow-spotted Keelback in Vietnam (photo by Alex Krohn)

juvenile Common Keelback Xenochrophis flavipunctatus neck

Juvenile Yellow-spotted Keelback found under board in Suan Luang

Michael Cota Xenochrophis flavipunctatus juvenile Nakhon Ratchasima

Juvenile Yellow-spotted Keelback in Nakhon Ratchasima (photo by Michael Cota)

Ray Hamilton Xenochrophis flavipunctatus juvenile Sattahip

Juvenile Yellow-spotted Keelback in Chonburi Province (photo by Ray Hamilton)

English name: Yellow-spotted Keelback (aka “Common Keelback”)
Scientific name: Xenochrophis flavipunctatus (formerly known as Xenochrophis piscator)
Thai name: Ngu Lai-so Suan, Ngu Daeng Hae

Description: Up to 120cm long. Body is roughly cylindrical and of average girth. Eyes are large. Has an olive-brown background coloration with various black streaks and blotches and a row of small yellow or white dots down each side. Two black streaks come down and back from the eye. Juveniles have a characteristic yellow mark on their neck that fades with age.

Similar Species: Checkered Keelback has a black checker pattern on an olive-brown background. It is a close relative and was once considered to be the same species.
Red-necked Keelback is more colorful and has a characteristic red neck. Juvenile Red-necked Keelbacks, which may not have developed the red neck yet, have a large black marking on the back of their neck that juvenile Yellow-spotted Keelbacks do not have.
Asian Water Snakes (subfamily Homalopsinae) generally have broader heads, smaller eyes, and much thicker bodies.
Oriental Rat Snake lacks black markings on the front half of its body.

Habitat: In or near marshes, ponds, or rice patties, sometimes in the middle of urban areas. The Yellow-spotted Keelback is a a strong swimmer.

Place in the ecosystem: The Yellow-spotted Keelback eats fish, frogs, and rodents, helping to control mouse and rat populations in the city. The juveniles are eaten by larger snakes and birds.

Danger to humans: Will bite aggressively when provoked and can draw blood, but is not dangerous to humans. Though it has no venom glands, some people report itching and slight swelling after a bite.

Conservation status and threats: No known conservation threats.

Interesting facts: The Yellow-spotted Keelback will often swallow its prey immediately upon catching it, without constricting or using any other means to kill the prey. As a result, prey is sometimes swallowed live, and some sources report frogs still vocalizing from within the snake.

References:
Snakes of Taiwan: Xenochrophis piscator
On the taxonomy of the Xenochrophis piscator complex
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
Snakes of Thailand and their Husbandry
Simon & Schuster’s Guide to Reptiles and Amphibians of the World

 

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Jack’s Water Snake

Homalopsis mereljcoxi

Puff-faced Water Snake Homalopsis mereljcoxi Jack's Water Snake buccata near Bangkok Thailand

Jack’s Water Snake in Nakhon Ratchasima Province (photo by Alex Heimerdinger)

Puff-faced Water Snake Homalopsis mereljcoxi Jack's Water Snake buccata near Bangkok Thailand

Head shot of Jack’s Water Snake (photo by Alex Heimerdinger)

Puff-faced Water Snake Homalopsis buccata near Bangkok Thailand

Jack’s Water Snake (photo by Alex Heimerdinger)

Jack's Water Snake Homalopsis mereljcoxi in  Nakhon Ratchasima Thailand

Jack’s Water Snake (photo by Alex Heimerdinger)

Homalopsis mereljcoxi Jack's Masked Watersnake

Jack’s Water Snake (photo by John Murphy)

Homalopsis mereljcoxi Jack's Masked Watersnake

Jack’s Water Snake (photo by John Murphy)

Puff-faced Water Snake (Homalopsis buccata) adult

Older adult Jack’s Water Snake (photo by Michael Cota)

Jack's Puff-faced Water Snake Homalapsis buccata mereljcoxi Vietnam Alex Krohn

Jack’s Water Snake trapped in Vietnam (photo by Alex Krohn)

Jack's Water Snake Puff-faced Water Snake Homalopsis mereljcoxi buccata roadkill

Jack’s Water Snake killed by car (photo by Alex Heimerdinger)

Jack's Water Snake Puff-faced Water Snake Homalopsis mereljcoxi buccata lumpani bangkok thailand

Jack’s Water Snake that had been released by tourist into Lumpani Park

English name: Jack’s Water Snake (aka “Jack’s Masked Water Snake”, “Puff-faced Water Snake”)
Scientific name: Homalopsis mereljcoxi (formerly Homalopsis buccata)
Thai name: Ngu Hua-kra-lok, Ngu Leuamao

Description: To 137cm long. Robust, somewhat flattened body. Notable broad, brown head with dark eyestripes, a “V” marking on top of the head and an inverted “V” on the snout. Has keeled scales. Body is dark brown to black with narrow light bands that fade in old age. Underside is white to yellow with small black dots.

Similar Species: Bocourt’s Water Snake has no face mask, is thicker and darker with black markings interspersed with the brown.
Red-tailed Pipe Snake has a small, dark head, smooth scales, and a barred underbelly.
Puff-faced Water Snake, which is not found in Bangkok, can only be distinguished by scale counts and range

Habitat: Rivers, lakes, ponds, swamps, rice paddies, drainage ditches, and any other lowland habitat with water, including brackish water. Can be found in the water or on the banks. During the day it hides in burrows and crab holes.

Place in the ecosystem: Jack’s Water Snake eats fish, crustaceans, and frogs. Juveniles of the species are eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: Can bite, but rarely does so and is not dangerous to humans.

Conservation status and threats: Due to its broad distribution and ability to live in human-altered habitats, this snake is not considered at risk in Thailand. It is becoming popular in the pet trade, but that has only had an effect on populations at the local level. In nearby countries similar species are declining due to massive collection for food, skins and crocodile feed.

Interesting facts: In September 2010, I came upon a juvenile Jack’s Water Snake in Lumpani Park. Upon viewing and photographing the snake, an American tourist nearby got anxious and stated, “I ask only that you do not harm the snake.” Further inquiry found that he had bought the snake at a Bangkok market and “humanely” released it into the Lumpani Park lakes. He had no idea whether the snake was a native species or whether it was venomous.

Releasing a captive animal into the wild, even a native one, is not good for the local ecosystems. Non-native species, such as the red-eared sliders in the ponds, the Norway rats in the streets, and the English house sparrows in the trees, may prey on, outcompete, or spread disease among local species. And even native species that have spent time in captivity are highly at risk for transmitting disease into the wild populations. If you purchase a captive animal and can no longer care for it, please find a responsible person to take over care for the animal rather than releasing it into the wild.

References:
The IUCN Red List: Homalopsis buccata
A Checklist and Key to the Homalopsid Snakes
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
A Field Guide to the Snakes of South Vietnam

 

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Yellow-bellied Water Snake

Hypsiscopus plumbea

Yellow-bellied Water Snake Hypsiscopus plumbea Enhydris plumbea coiled to strike

Yellow-bellied Water Snake found on road near ponds in Phayao Province

Third Rice Paddy Snake Hypsiscopus plumbea Enhydris plumbea from same spot

Another Yellow-bellied Water Snake in Phayao Province

Yellow-bellied Water Snake Hypsiscopus plumbea Enhydris plumbea

Yellow-bellied Water Snake found in mud in Phayao Province

Yellow-bellied Water Snake Hypsiscopus plumbea Enhydris plumbea

Yellow-bellied Water Snake found under fish pond rock in Kanchanaburi Province

Rice Paddy Snake Hypsiscopus plumbea Enhydris plumbea nostrils and eyes

Close-up of Yellow-bellied Water Snake

Two Gray Water Snakes Hypsiscopus plumbea Enhydris plumbea

Two Yellow-bellied Water Snakes found under rock in Laos

plumbeous water snake Hypsiscopus plumbea enhydris plumbea

Yellow-bellied Water Snake in Vietnam (photo by Eduard Galoyan)

Yellow-bellied Water Snake Hong Kong eating frog enhydris plumbea

Yellow-bellied Water Snake eating frog in Hong Kong (photo by Anne Devan-Song)

Yellow-bellied Water Snake Hypsiscopus plumbea  Kevin Messenger China 1

Yellow-bellied Water Snakes in China (photo by Kevin Messenger)

rice paddy snake Enhydris plumbea  Kevin Messenger China

Yellow-bellied Water Snake showing unusual ventral color (photo by Kevin Messenger)

English name: Yellow-bellied Water Snake (aka: “Plumbeous Water Snake” or “Rice Paddy Snake”)
Scientific name: Hypsiscopus plumbea (formerly Enhydris plumbea)
Thai name: Ngu Pling

Description: To 77cm long. This small water snake has a moderately broad head and smooth scales. It is uniformly dark above with a pale cream to yellow underbelly.

Similar Species: Rainbow Water Snake has a smaller head and colored lines going down its body.
Jagor’s Water Snake has small dark blotches down its sides.
Chanard’s Mud Snake has a pale line down its side and a row of small dark dots above the line.
Sunbeam Snake is iridescent, has a narrow wedge-shaped head, and is whitish-gray on the bottom.
Red-tailed Pipe Snake has a small head and a barred underbelly.
Yellow-striped Caecilian lacks scales, has yellow stripes on the side rather than a yellow belly, and has a distinctly non-snake-like head.

Habitat: Slow-moving rivers, ponds, swamps, rice paddies, and other wetland habitats with stagnant water. Forages from dusk until dawn. Found on land more often than other water snakes, but rarely far from the water.

Place in the ecosystem: Feeds on fish and frogs. Eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: The Yellow-bellied Water Snake will aggressively strike when cornered on land, but its small size keeps it from being able to inflict much damage. While it is a rear-fanged snake with some venom, the venom has a limited effect on humans, possibly leading to some swelling in the worst cases.

Conservation status and threats: No known conservation issues. This is a common species in Thailand, though its population in Taiwan is endangered.

Interesting facts: Yellow-bellied Water Snakes are excellent swimmers but move awkwardly on land. When faced with a threat on land, they will sometimes flip their bodies up into the air and backwards with a reverse-striking motion, propelling themselves erratically towards the water.

References:
Snakes of Taiwan: Enhydris plumbea
Reptiles of Hong Kong: Enhydris plumbea
The IUCN Red List: Enhydris plumbea
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
A Field Guide to the Snakes of South Vietnam

 

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Rainbow Water Snake

Enhydris enhydris

Rainbow Water Snake Enhydris enhydris

Rainbow Water Snake found in Pathum Thani Province (photo by Michael Cota)

Rainbow Water Snake Enhydris enhydris malaysia

Rainbow Water Snake in Malaysia (photo by Tom Charlton)

Rainbow Water Snake Enhydris enhydris Vietnam Alex Krohn

Rainbow Water Snake trapped in Vietnam (photo by Alex Krohn)

Rainbow Water Snake Enhydris enhydris Vietnam Alex Krohn 1

Snake in hand, showing underbelly coloration (photo by Alex Krohn)

Rainbow Water Snake enhydri enhydris lake sonhkla

Rainbow Water Snake in Lake Songkhla (photo by John Murphy)

Rainbow Water Snake Enhydris enhydris

Rainbow Water Snake in captivity in Bangkok (photo by Wolfgang Wuster)

Tom Williams enhydris enhydris Rainbow Water Snake Pathum Thani

Juvenile Rainbow Water Snake in Pathum Thani (photo by Tom Williams)

Rainbow Water Snake enhydris maetha lampang

Head shot of Rainbow Water Snake in Lampang Province (photo by Bernard DuPont)

Water Snakes for sale in Vietnamese market

Water Snakes for sale in Vietnamese market (photo by Alex Krohn)

Common Smooth-scaled Water Snake kolkata india dead

Rainbow Water Snake killed by field worker in India

English name: Rainbow Water Snake (aka “Rainbow Mud Snake”, “Striped Water Snake”, “Schneider’s Water Snake”)
Scientific name: Enhydris enhydris
Thai name: Ngu Sai-rung, Ngu Plaa

Description: To 97cm long. Robust body with relatively small head for a water snake. Scales are smooth and iridescent. Olive-brown above with two yellow or reddish stripes bordered by dark stripes on the top and sides. White to yellow below with a dark stripe or dots down the center of belly.

Similar Species: Yellow-bellied Water Snake has a broader head and lacks colored lines.
Sunbeam Snake has a wedge-shaped head, more iridescent scales, and lacks colored lines on its body.
Red-tailed Pipe Snake lacks colored lines and has a barred underbelly.
Chanard’s Mud Snake has a broader head and dark spots above the line running down its side.
Jagor’s Water Snake has a broader head and dark blotches running down its side.
Mekong Mud Snake has dark markings in addition to light stripes.

Habitat: A highly aquatic species that is always found in or near wetlands. Is found in a wide range of aquatic habitats, including manmade lakes and ponds. Spends most of its time hunting just off the shore, taking advantage of the tangles of vegetation in the mud at the water’s edge. Is rarely seen in the open, preferring to remain underwater or within vegetation mats and tangles. Does not tolerate brackish water.

Place in the ecosystem: Primarily feeds on fish, but also frogs and tadpoles. Is eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: Like other water snakes in its family, the Rainbow Water Snake has a very mild rear-fanged venom that does not pose a threat to humans.

Conservation status and threats: Due to its ability to survive in a wide range of habitats and tolerate human encroachment, the Rainbow Water Snake is a common species in Thailand. However, a recent increase in the harvest of water snakes in Cambodia (for food, skins, and crocodile feed) has led to declines in some populations there. As many as four million Rainbow Water Snakes are estimated to be captured from the Tonle Sap Lake every year.

Interesting facts: Water snakes have a number of specialized traits to support their aquatic lifestyle. These include eyes positioned on top of the head (to see prey and threats while remaining underwater), nostrils that can be closed while underwater, and young that are born live (eliminating the need for a dry place to lay eggs).

References:
The IUCN Red List: Enhydris enhydris
Reptiles Magazine: Mud Snakes
Semi-aquatic Snake Communities in the Central Plain Region of Thailand
The Ecology of the Water Snakes of Ban Tha Hin, Songkhla Province, Thailand
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
A Field Guide to the Snakes of South Vietnam

 

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Bocourt’s Water Snake

Subsessor bocourti

Bocourt’s Water Snake  Enhydris Subsessor bocourti malaysia

Bocourt’s Water Snake in Malaysia (photo by Tom Charlton)

Bocourt’s Water Snake Subsessor bocourti Enhydris Malaysia

Head shot of Bocourt’s Water Snake (photo by Tom Charlton)

Bocourt’s Water Snake Subsessor bocourti Enhydris Malaysia

Bocourt’s Water Snake in water (photo by Tom Charlton)

Bocourt's Water Snake Subsessor Enhydris bocourti

Bocourt’s Water Snake (photo by Alex Krohn)

Bocourt's Water Snake Subsessor Enhydris bocourti

Bocourt’s Water Snake (photo by Alex Krohn)

Bocourt's Water Snake Subsessor Enhydris bocourti head shot

Bocourt’s Water Snake head shot (photo by Alex Krohn)

Bocourt's Water Snake Subsessor Enhydris bocourti

Bocourt’s Water Snake in hand (photo by Alex Krohn)

adult Bocourt's Mud Snake Enhydris bocourti

Bocourt’s Water Snake (photo by of John Murphy)

Bocourt's Mud Snake juvenile Enhydris bocourti

A juvenile Bocourt’s Water Snake (photo by John Murphy)

Water Snakes for sale in Vietnamese market

Water Snakes for sale in Vietnamese market (photo by Alex Krohn)

English name: Bocourt’s Water Snake
Scientific name: Subsessor bocourti (formerly Enhydris bocourti)
Thai name: Ngu Zi, Ngu Leuam-ao

Description: To 110cm long. The largest, most robust of the water snakes in Thailand. Head is large and blunt. The smooth-scaled body has large brown blotches/bands with black borders that narrow on the sides, with yellow bands in-between that broaden correspondingly. Brown areas sometimes have thin tan-to-orange line in the center. Both the light and dark coloration becomes more indistinct as the snake ages. Head is reddish-brown with a cream upper lip and red eyes. Underbelly is yellowish-white.

Similar Species: Jack’s Water Snake has keeled dorsal scales, is usually not as robust, is lighter in color, and has a distinct dark face mask.
Jagor’s Water Snake has simple dark blotches rather than the more extensive dark pattern.

Habitat: Found in swamps, ponds, shallow lakes, rice fields, and other stagnant waters in lowlands. Is highly aquatic and usually stays near water, but will travel over land during rainy nights. Conceals itself among logs in or near water during the day.

Place in the ecosystem: Eats fish and frogs. Is eaten by larger snakes, large fish, monitors, and wading birds.

Danger to humans: Though Bocourt’s Water Snake is a rear-fanged species its venom is not a threat to human. It is not aggressive, but if restrained its large size and sharp teeth allow it to give a nasty, painful bite.

Conservation status and threats: There are no known serious threats to its Thai populations. However, Bocourt’s Water Snake is harvested for its meat and skins in several countries. In Cambodia’s Tonle Sap Lake, extended overharvest has led to the species being rarely found and it now comprises only a small proportion of the annual snake catch. There have also been declines due to overharvest in Vietnam. Much of the hunting of snakes in both countries has been constrained, but enforcement is minimal and there are concerns that many snake populations are collapsing.

In some areas Bocourt’s Water Snake has begun to be farmed in large numbers, which could relieve pressure on wild populations.

Interesting facts: Like many water snakes, Bocourt’s Water Snake releases a foul-smelling musk and feces when handled.

References:
IUCN Redlist: Enhydris bocourti
How the world’s largest snake hunt hurts Southeast Asia’s biggest lake
The Last Days of the Mekong Snake Hunters
A Photographic Guide to Snakes and Other Reptiles of Peninsular Malaysia, Singapore and Thailand
A Field Guide to the Reptiles of South-East Asia
A Field Guide to the Snakes of South Vietnam

 

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Keel-bellied Water Snake

Bitia hydroides

Keel-bellied Water Snake bitia hydoroides

Keel-bellied Water Snake near mudskipper hole in Malaysia (Photo by M.A. Muin)

Keel-bellied Water Snake Bitia hydroides

Keel-bellied Water Snake killed in Malaysia by fisherman (Photo by M.A. Muin)

Keel-bellied Water Snake Bitia hydroides

Head shot of Keel-bellied Water Snake (Photo by M.A. Muin)

Keel-bellied Water Snake Bitia hydroides

Close-up of head and scales of Keel-bellied Water Snake (Photo by John Murphy)

English name: Keel-bellied Water Snake
Scientific name: Bitia hydroides
Thai name: Ngu Pak-Kwang Tong San

Description: To 90 cm long. Slender body is slightly flattened vertically, with a short tail that narrows to a point. Head is small and blunt with bulging grey eyes. Body is cream/white turning to yellow on the top, with black bands. Belly is white, with unusual keeled scales.

Similar Species: Dog-faced Water Snake has a darker upper body with clear dorsal/ventral contrast.
Little Wart Snake is heavy-bodied, has a distinctly different head shape, and skin that hangs loosely.
Venomous sea snakes of the Elapidae family can appear similar to this harmless species, though they have blunter, more paddle-like tails that don’t narrow down to an elongated point.

Habitat: This species is only found in coastal river mouths and nearby mudflats, though it may hunt in deeper waters. They are proficient burrowers and may spend most of their time in the mud.

Place in the ecosystem: Eats fish in the mudflats, especially mudskippers (gobies). May be eaten by larger snakes, monitors, crocodiles, large fish, or wading birds.

Danger to humans: Though quite similar to a sea snake in appearance, this species is completely harmless to humans

Conservation status and threats: Less than 200 specimens of the Keel-bellied Water Snake have ever been found. However, those specimens were found over a wide range, and in at least one locality were extremely common (over 100 of the snakes found in a few months). It is currently believed that the Keel-bellied Water Snake is simply difficult to locate rather than rare, but the infrequent observations of the species make it impossible to determine its true abundance. Please contact this website if you have any sightings or photos of this species.

Interesting facts: The Keel-bellied Water Snake has enlarged palentine teeth, an unusual characteristic shared by only one completely unrelated species of snake. The reason behind these enlarged teeth is unknown.

References:
IUCN Red List: Bitia hydroides
The Reptile Database: Bitia hydroides
Morphology, Reproduction, and Diet of the Marine Homalopsine Snake Bitia hydroides in Peninsular Malaysia
Michael Cota, Personal Communication.

 

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