Reptiles
Elephant Trunk Snake
Acrochordus javanicus · also called elephant trunk snake, javan file snake, wart snake
The elephant trunk snake looks like a snake wearing a skin suit two sizes too big. Its loose, folded, warty hide sags off a thick body, its scales feel like coarse sandpaper, and out of water it can barely move. That is fine, because it almost never leaves the water — this is a snake that spends its whole life submerged, using its rough skin to hold onto slippery fish.
Overview
The elephant trunk snake lives in the fresh and brackish waters of Southeast Asia — rivers, lakes, rice paddies, mangroves, estuaries, and coastal shallows. It reaches 1.8–2.4 m, dull grey-brown, with baggy skin covered in thousands of tiny, pointed, non-overlapping scales that feel like a file. It eats fish, seizing them and wrapping them in coils underwater.
An aquatic specialist
It has no enlarged belly scales, so on land it can only drag itself feebly, and it spends essentially its entire life submerged. Its skin is richly supplied with blood vessels and takes up oxygen from the water, so it can rest on the bottom for long periods between breaths. Females give live birth directly into the water.
The file skin
The rough, granular scales give the snake a strong grip on slippery fish — it pins prey against its own body coils, where the friction stops the fish sliding free until it tires.
Status
The elephant trunk snake is Least Concern but declining. Its baggy skin was made into a leather traded as karung, and large numbers were taken from the wild; it is also hit by wetland drainage, pollution, and net bycatch. It is harmless to people.
Elephant Trunk Snake: common questions
Why does the elephant trunk snake have such loose, baggy skin?
The slack, folded skin, which looks as if it belongs on a much larger animal, is an adaptation to aquatic life. It gives the body a soft, flexible surface that conforms around a struggling fish, and together with the rough scales it helps the snake grip and pin prey underwater. The loose skin also has a large surface area relative to the snake's volume, which aids the skin breathing the snake relies on to extend its dives. On land the same skin just sags, and combined with the lack of gripping belly scales it is one reason the snake is so poorly suited to moving out of water.
What are the file-like scales for?
Grip. The snake's scales are small, pyramid-shaped, and keeled, and they do not overlap like roof tiles the way a typical snake's do; instead they stud the skin like the teeth of a file or a sheet of coarse sandpaper. When the elephant trunk snake catches a fish, it cannot rely on constriction alone because a slippery, thrashing fish is hard to hold, so it wraps the prey against its own body and the friction of those rough scales keeps the fish from sliding free until it tires and can be swallowed. The same texture gives the snake its alternative names of file snake and wart snake.
Is the elephant trunk snake dangerous to people?
No. It has no venom, its teeth are small and made for holding fish, and it is a slow, placid animal that will try to escape rather than bite. Its defensive options amount to little more than releasing a foul-smelling musk. Fishers who catch one in a net can handle it without harm beyond the discomfort of a large, heavy, slimy, sandpaper-textured snake. It poses no threat to swimmers or to anyone working in the waters where it lives.
Can it be kept in an aquarium?
It is kept by specialist reptile keepers but is genuinely difficult and not recommended for most people. It needs a large, deep, filtered aquatic setup with pristine water, since it is prone to skin infections and blistering if water quality slips, and it must be fed a steady diet of appropriate fish. It is also stressed by handling, does not do well out of water even briefly, and much of the supply has been wild-caught animals that adapt poorly. For the great majority of interested keepers it is better appreciated in public aquariums.