Tentacled Snake

They are sensory organs for detecting prey. The two short, scaled appendages on the front of the snout are densely supplied with mechanoreceptors that respond to touch and to tiny movements of the water, and each connects to an enlarged, dedicated area of the snake's brain, showing how important the input is. As a fish swims nearby, its body and fins push water around, and the tentacles pick up that displacement. This lets the tentacled snake locate and track a fish it cannot see — at night, in muddy water, or with its own eyes partly out of the water — and time its strike precisely. It is the only snake known to have this structure.

It weaponises the fish's own reflexes. The snake anchors its tail, holds the front third of its body in a rigid J-shape just above the bottom, and waits with its head near the opening of the J. When a small fish swims into that gap, the snake makes a small, sharp feint with the side of its body away from its head. The fish detects this water disturbance and instantly fires its "C-start" escape response, a hard-wired reflex that snaps its body into a C and launches it away from the threat — but because the feint came from one side, the fish bolts toward the snake's head, which is already positioned and aimed. High-speed video shows the snake begins its strike before the fish even moves, predicting where the reflex will send it. Success rates are very high.

It has a mild rear-fanged venom that it uses to help subdue fish, delivered by grooved teeth at the back of the upper jaw. It is essentially harmless to humans — it is small, extremely reluctant to bite (its usual response to being handled is to go completely stiff, like a stick), and its fangs are positioned so far back that envenomating a person would be difficult even if it tried. There are no reports of medically significant bites. The bigger practical issue for keepers is that the snake is a delicate, specialised aquatic animal, not that it is a threat.

They are kept by experienced aquarium and reptile hobbyists, and captive breeding does occur, but they are a specialist animal. They need a heated aquarium with soft, still, slightly brackish or fresh water, dense planting or branches to anchor and hide among, and a steady supply of live feeder fish, since many individuals will not take dead food. They are almost motionless most of the time and spend the entire time in water. Wild-caught imports often arrive stressed, underweight, or carrying parasites, and the species does poorly if water quality or temperature is not carefully maintained, so captive-bred stock and a well-cycled system are important.