Subsessor

Subsessor belongs to the family Homalopsidae, the mud snakes or Indo-Australian water snakes. This is a family of roughly 50 to 60 species built almost entirely for life in water, with eyes and nostrils set high on the head and valved nostrils that close when submerged. Subsessor contains very few species and is best represented by Bocourt's Water Snake, a heavy bodied snake of freshwater and brackish habitats in mainland Southeast Asia. The genus is sometimes treated alongside or split from the better known genus Enhydris, which reflects how much homalopsid classification has been reshuffled as researchers study the group.

Like other homalopsids, members of Subsessor are tied to wetlands. They favor slow rivers, canals, rice paddies, swamps, and the muddy margins where fresh and brackish water meet. They are mostly nocturnal and spend their time in or right next to the water, hunting fish and frogs and swallowing prey underwater. Recognition at the family level comes from the thickset body, the dorsally placed eyes, smooth to weakly keeled scales, and the strongly aquatic habits, rather than from any single bright marking. Coloration tends toward dull browns, grays, and olive tones that blend with mud and shaded water.

Homalopsids, including Subsessor, are rear-fanged and mildly venomous. The venom is delivered through enlarged grooved teeth at the back of the upper jaw and is used to subdue small aquatic prey. These snakes are not considered dangerous to people, and bites generally cause only minor local effects, but rear-fanged venom is a real biological tool, not a guarantee of harmlessness. Do not handle wild snakes. If anyone is bitten and symptoms develop, or there is any uncertainty about the species, seek medical care and contact US Poison Control at 1-800-222-1222 or your local emergency services. Like many homalopsids, these snakes give birth to live young rather than laying eggs, an adaptation suited to their aquatic lifestyle.