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Tentacled Snake, Erpeton tentaculatus, has its name derived from the presence of fleshy, tentacle-like structures on the snake’s face. The Latin tentaculum meaning “feeler.” In English this species is also called: the fishing snake or the tentacled fishing snake. The tentacled snake is endemic to the Indochinese Peninsula (Thailand, Cambodia, and south Vietnam). Despite the fact that Malaysia and Indonesia are often cites as locations for this species, voucher specimens are unknown from these localities. Its known distribution suggests it occurs in an arc around the Gulf of Thailand, with the southernmost population present in the area around Lake Songkhla, Thailand.
The rostral appendages of this snake, commonly referred to as tentacles, make this species highly distinctive and impossible to mistake for any other homalopsid or for that matter any other known snake.
The largest snake measured was a female with a total length of 767 mm with a 231 mm. The largest male measured had a total length of 724 mm and a 246 mm tail. Morice (1875) reported a snake with a total length of 920 mm, with a 220 mm tail. The smallest specimen he reported had a 213 mm SVL and a total length of 273 mm. Martinez and Behler (1988) found neonates ranged in length from 197 - 244 mm. The tail is proportionally the longest in any homalopsid; and combining all populations the T/SVL ratio is 43 - 59% in males, and 33 - 44% in females.
There are two scale covered rostral tentacles that are 4 - 5 mm long in adults. These tentacles make this the most readily recognizable snake on the planet. The eyes are relatively large and lateral; and the eye diameter is greater than the eye-mouth distance, the only described homalopsid having this character state. In dorsal view the eyes bulge from the side of the face. The body is depressed, and some individuals have the lowest ventral count for any homalopsid (some have as few as 91 ventral scales). Most Thai specimens are orange with brown markings and white spots, while some specimens are black with gray markings and white spots. Three captive females gave birth, each litter was composed of young with both of these color morphs, the color morphs are distinct and suggest the coloration does not seem to change with age.
The tentacled snake uses stagnant or slow moving bodies of water. The habitats examined contained substantial amounts of emergent-submergent vegetation; it seems likely that this species rarely leaves the water. Erpeton is strictly piscivorous. Its ambush hunting behavior was well documented by several authors. Erpeton uses an immobile, rigid, J-shaped posture when in hunting mode. It lies in the water and waits for fish. Recently, Catania (2010, 2011) has documented how Erpeton exploits the C-start escape response of fish during feeding, essentially the snake uses a muscular wave of its body to encourage the fish to move towards its mouth. When striking at small fish, they are often swallowed with the strike.
Erpeton has litters of 5 - 13 young based upon the literature (Morice, 1875a; Smith, 1943; Campden-Main, 1970). Martinez and Behler (1988) reported on seven litters born at the New York Zoological Park; parturition occurred from early July to early October; litter size ranged from 5 - 12 (= 7.9); neonates ranged from 197 - 244 mm in total length, and from 2.4 - 5.0 g. Courtship was observed only once, on 24 February.
Humans are the only known predators of Erpeton; Stuart et al. (2000) found that it was occasionally collected with other homalopsids during the snake harvest at Tonlé Sap, Cambodia. This species made up a small percentage of the catch and was not considered useful for human or crocodile food. Nor, was it used for leather products. When caught it was frequently discarded because of the belief it was poisonous. He (Stuart, 2004) also noted it was collected by fishermen in the Mekong Delta. Morice (1875b) noted that the Annamites consider this species venomous, writing, "The bite is thought to cause an endless sleep, from which even a beating would not awaken one, and which would end slowly in death."
The cryptic posture of this species was described by Smith (1943) he wrote, “When this snake is handled it does not attempt to bite or escape, instead it stiffens its body, a habitat that has earned for it the Thai name of “ngu kradan” or the “snake like a board.” A captive snake placed in an aquarium with one floating water hyacinth proved to be remarkably cryptic. Its body posture and coloration combine to make it appear part of the vegetation. Its cryptic nature is also enhanced by the growth of algae on the skin. When placed in clean water the symbiotic algae is readily visible and the fish (Betta splendens) in the aquarium would graze along the snake’s body, thus besides serving as camouflage the algae may also serve to attract prey.