That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

Southeast Asia’s bizarre tentacled snake (Erpeton tentaculatum) is a long-time favorite of mine and I’ve kept and bred a great many in zoo collections over the years.  Despite watching them intently for so long, I’ve never quite been able to figure out how they manage to so effectively catch fast-moving fishes while striking out in a direction that seems designed to insure that they miss the intended target.

A Unique Escape Strategy

Recently published (Vanderbilt University, Tennessee: June, 2009) research has provided the answer.  Many fishes, it seems, utilize an escape maneuver known as the C-Start.  Upon sensing danger, the body contorts into a “C” shape, the tail is flicked and the fish, in a millisecond, darts away.

Exploiting the Defensive Maneuver

Tentacled snakes, anchored to submerged objects by their tails and resembling water-logged roots, lie in wait for passing fishes.  The snake always holds itself in a very distinctive “J” shaped position.  As a fish approaches, the snake “feints” with its body by sending a ripple of water towards the fish.  This incites the C-Start reaction and propels the fish directly toward the snake’s jaws.

Once initiated, the C-Start maneuver cannot be altered, so the hapless fish is doomed.  The snake’s “J” position allows it to strike not at the fish but rather where the fish will be once it flees.  What’s more, the strike nearly always catches the fish in the head region, assisting the snake in swallowing its slippery prey.

Further Reading

To learn more about the natural history and captive care of tentacled snakes, please see my article The Tentacled Snake, an Unusual Pet Serpent .

Introduction
The snake world is full of species that “break the mold” – none more so than a Southeast Asian import that sometimes appears in the trade, the tentacled snake.

The care of this snake differs greatly from that of all others, and I’ll devote a full article to it shortly.  For now, I’d like to introduce the species to those of you who may be looking for a new challenge.

The Tentacles

The tentacled snake is unique among snakes in its possession of 2 fleshy tentacles (adjacent to the nostrils), the function of which is still unknown.  It has been suggested that they have a sensory function, detect water movement, lure prey or break up the outline of the head.

Unique Adaptations
This inactive snake resembles a water-logged root, an effect that is heightened by its color, rigid posture, habit of remaining anchored to sunken branches, and the covering of algae that grows on the scales.  It rarely swims, waiting instead for fish to approach closely before striking.

Completely aquatic, this species lacks the broad ventral scales of terrestrial snakes and is helpless on land.  When disturbed, it becomes rigid and immobile (in Thailand, it is known as the “Board-like Snake”).  The nostrils can be sealed to exclude water, and it may remain submerged for 30 minutes before surfacing to breathe.  Tentacled snakes are thought to aestivate by burrowing into the mud during droughts.

Tentacled snakes produce mild venom that is effective against the fishes and tadpoles upon which they feed.  The venom has not been shown to be dangerous to humans – the two people I know of who have been bitten experienced mild swelling that disappeared within a few hours.

Unusual Relatives
The subfamily to which this species belongs, Homalopsinae, contains a number of aquatic snakes that frequent unique habitats and hunt in unusual ways.  For example, the white-banded mangrove snake, Fordonia leucobalia, hunts crabs on tidal mud flats in Southeast Asia and northern Australia.  It is quite effective at overcoming this unusual prey – utilizing constriction and crab-specific venom before finally tearing off the crab’s legs.  It may even employ its oddly blunted teeth to help crush its victims’ hard shells – the only snake known to use teeth in such a fashion.

Further information on tentacled snake natural history, as well as a picture, is posted at:
http://eobasileus.blogspot.com/2008/02/utterly-outrageous-tentacled-snake.html