Many people will never see an Asian Water Snake due to their secretive lives in the muddy water of ponds, swamps, canals, and estuaries. As John Murphy writes in Evolution in the Mud, these snakes have adapted to spend up to 99% of their time under the water, such as having eyes and nostrils positioned at the top of the head to peek just above the water’s surface.
One of the most uniquely adapted of all Thai snakes is the Tentacled Snake, named for the duel tentacle-like appendages that protrude from its face. These appear to sense the movements of fish in an ambush hunting strategy unique to the species. Its flattened body is almost useless for crawling and thus it rarely leaves the water. Another extreme is taken by Bocourt’s Water Snake, which has developed a fat heavy body easily buoyed by the water which it also almost never leaves.
Unfortunately, these aquatic preferences have put some Asian Water Snake species in danger. The swamps and marshes of the Chao Phraya River basin have been developed by Bangkok and other cities such that two local species, Jagor’s Water Snake and Chanard’s Mud Snake, are both nearly extinct. The Mekong Mud Snake has done somewhat better as it lives in the less developed Mekong River Valley, while its close relative the Rainbow Water Snake has become a habitat generalist, thriving even in agricultural ponds and city canals, and thus is still common through south and southeast Asia.
There are a few members of the group that are somewhat more comfortable on land. The Homalopsis species, which includes the Puff-faced Water Snake, Martaban Water Snake, Jack’s Water Snake, and Deuve’s Water Snake, can be seen on both land and water around streams, canals, and even estuaries. And the most land-adapted of them all is the Yellow-bellied Water Snake, which spends as much as 50% of its time hunting frogs on mudflats and riverbanks.
Several species have adapted to salt water. Dog-faced Water Snake and Keel-bellied Water Snake are predators of the gobies (mudskippers) that live in burrows on the mangrove mudflats. A different route has been taken by the Glossy Marsh Snake, Crab-eating Water Snake, and Cantor’s Water Snake, each of which has adapted to hunt crabs and mud lobsters in unique and fascinating ways.
Though several species (like the distinctly banded Cantor’s Water Snake) are quite obvious in appearance, many can only be identified by noting subtleties in their pattern and scales. You can see how to distinguish the different species from each other at the Guide to Identifying Asian Water Snakes in Thailand.
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