Hognose Snake: Mimicry in the Spreading Adder

By Renn Tumlison, tumlison@hsu.edu

 Many people have heard of the “spreading adder.” The name comes from the disturbed snake’s tendency to spread its neck – reminiscent of a cobra – so people think it mimics the cobra (photo). Mimicry works only if imposters mimic something in their own habitat. Otherwise, nothing is fooled by the copy. Cobras do not occur in North America, so our snake, also known as the Eastern Hognose Snake (Heterodon platyrhinos), cannot mimic it.

Spread2

 So why does the hognose spread its neck? It’s a bluff to make the snake look large and imposing. Another bluff is to play dead. The snake rolls onto its back and lays there. This behavior would make the snake easy to kill, so why would the snake do it? Most predators eat what they kill (otherwise, they would be scavengers). If a potential food item looks sick or dead, most predators have little interest in eating it. These snakes are harmless. If you find such a snake playing dead, you can repeatedly turn it back over, and it will turn over again. The snake wants to convince you that something is wrong with it, so it keeps going “belly up.”

The hognose sometimes makes an impressive noise by exhaling a blast of air, resulting in another common name: “hissing adder.” Although the snake may seem scary when spreading, hissing, or playing dead, it eats toads for a living. Toads also like to swell up when threatened, so the snake uses a special longer tooth to puncture the lungs of the toad, so it can be swallowed more easily. To see photos of the process of eating a toad, click here. Although this snake is harmless, to an untrained eye it may look like a copperhead or cottonmouth, so it is much better not to experiment with these behaviors unless you are absolutely certain of the identification of the snake. Further complicating identification, variations in coloration are common in individuals, even from the same geographical area (see photo below). 

Two Color Morphs
 
 
 
 
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