Mud Snake: Farancia abacura

Tuesday, August 4, 2009

Nature Notes
by Bob Thomas

The mud snake, Farancia abacura, is a large (up to six feet) spectacularly colored snake. They are abundant in swamps and associated wetland habitats, but rarely seen due to their secretive mannerisms and their glossy, iridescent black backs blending into the dark water.

Their bright red bellies are obvious when the animals are held, or when you speed by one on the highway that has been run over. Among our snake fauna, they are unique in this coloration. I call them "70 mph" snakes, since their coloration allows them to be easily identified to species at 70 mph.

Fortunately for them, they spend most of their time in swamps, and rarely cross highways.
This contrast of pattern--dark on the back and light on the belly--is common in the aquatic world. Scientists call it counter shading, and it helps them avoid predation. If a predator is above them, the dark back tends to blend into the darkness of the water depths; if below, the light belly blends into the brightness of the sky light.

One of the mud snakes' behaviors (see photos) further explains the contrast. When approached by a predator, they often place their heads beneath a coil of the body and curl the tail while holding it upside down and elevated. The bright color may either frighten the predator or draw its attention from the snake's head. A snake with a chewed tail has a better chance of survival than one with a chewed head. This behavior is common among brightly patterned snakes, especially the coral snakes.
The mud snake is truly an important example of animal misunderstandings and resulting myth.

They have a habit of lying in the water in a perfect circle. Large specimens look like a wheel, so the story has been passed down that they take their tails in their mouths and roll down a hill--the so-called hoop snake.

Since the mud snakes live in swamp habitats and stealthily move in search of prey, they use a technique that mirrors a man using a pole to push his pirogue forward. The tips of their rather short tails have a pointed terminus, and they push the "spike" into the mud, and push away to move forward. When picked up, mud snakes often push this spiny tip into the holder's arm to gain purchase. Someone who doesn't know snakes might think the snake is trying to "sting" him--thus the common name "stinging snake." I've handled many mud snakes, most have exhibited this behavior, and I never felt pain.

When I was young and living in central Louisiana, I was often told that stinging snakes "take their tails in their mouths, roll down a hill, and sting a tree at the bottom. My grandfather actually saw this happen, and the dead tree is still there." It took personal fortitude not to roll my eyes.

Interestingly, mud snakes show no aggression against humans. I have encountered more than 100 in the field, and each time I simply picked the animal up in the middle of the body and have never seen one even open its mouth, much less snap at me.
Their bodies are soft to the touch, without strong muscle tone.

When it come to their prey, however, they are vicious in their attacks. Mud snakes predominately eat amphiumas, although they are bound to occasionally feed on sirens (another eel-like salamander) and other salamanders. Fish and frogs have also been reported in their diets. David Muth, chief of planning and resource stewardship at Jean Lafitte National Historical Park and Preserve, tells of talking to a visitor on the ring-levee trail at the park's Barataria Unit. There was a sound nearby and they saw a foot-long three-toed amphiuma (Amphiuma tridactylum) about as thick as a human thumb shooting into the air out of a crawfish chimney pushing a little fountain of water ahead of itself. It was immediately followed by a two-foot-long mud snake. The amphiuma slithered through the shallow swamp water, then disappeared down another hole with the snake in hot pursuit. This game of "nature tag" is constantly in play throughout these species' range.

Mud snakes lay up to 100 eggs and the female stays with them until they hatch in the late summer or early fall.

These are glorious snakes, and I hope all naturalists have a chance to enjoy their beauty, especially in their natural habitat.


Mud snake, Farancia abacura.                                                Red belly of a mud snake.
Photo by Brad Moon.                                                           Photo by Brad Moon.


Defensive display of a mud snake.                                          Typical defensive display. Note the snake
The coiled tail with red turned up                                            is hiding its head beneath a coil, but it
distracts a predator from the head.                                         has lowered its tail.
Photo by Brad Moon.                                                            Photo by Brad Moon.


Mud snake eating an amphiuma.                                           Pointed tip of a mud snake tail, used to
Photo by Brad Moon.                                                        push through its habitat like a push-poler
                                                                                          in a pirogue.
                                                                                            Photo by Bob Thomas.