Yikes! If that doesn't convince you there's danger lurking in the grass, I don't know what will, but it's all an act. Eastern Hognose snakes are harmless to humans. If you look in that gaping maw (and how can you not?) you'll see there are no fangs to deliver venom. There are teeth in the back (rear fangs), but they are mainly used to puncture inflated toads (their favorite food) and hold them in place (toads will sometimes inflate their bodies when captured to try to keep from being swallowed, but a hognose takes care of that minor problem in short order!).
When I was looking at the above photo, it dawned on me that I saw no tongue. Where on earth was it? Then I noticed the sheath on the bottom jaw...ahhh haaaa! A snake's tongue is encased in a sheath in the lower jaw when it is retracted. Since a snake's tongue is so integral to its survival, it only makes sense it would have evolved with a sheath to protect the tongue from injury.
When alarmed, an Eastern Hognose Snake will flatten out its head and neck to form a cobra-like hood. Here you can see he's just starting to produce the flaring hood, which is one of his tricks to try to convince you he's venomous and dangerous. Venomous snakes have triangular-shaped heads, while non-venoums snakes have more oval-shaped heads, but if you look at his eye you can see it's all a ruse. He has oval-shaped pupils, which means he is non-venomous. Venomous snakes have elliptical-shaped pupils.
...and from straight on...ack! That is one dangerous-looking snake. His head screams triangle and his little triangular-shaped snout (the hognose namesake) only adds to his fierceness. Of course, once again, his round pupils give away the fact that he's nonvenomous and harmless...
...and if all that blustering doesn't scare you away, the hognose then does the next best thing. He plays dead, flipping over on his back and lolling out his tongue!
...yes, he actually lolls out his tongue, which is a clever touch because he really does look quite dead! If you want an encore performance, just flip him over. He will immediately flop onto his back again...and loll out that tongue as well!
Matty and I watched this grand performance on 6/29/2011 at Shawnee State Park in Ohio when we were volunteering with Jenny Richards, the park's amazing naturalist. You learn and get to see so much when you volunteer in the parks!
Note: The hognose snake has another method of defense. It will inflate its body with air by expanding its lung like a balloon (most snakes have only one functioning lung that extends most of the length of its body). It then lets the air out emitting a loud hissing sound. I couldn't capture this with the camera... This behavior accounts for many of its common names of "puff adder, blow snake, and hissing viper" (common name source: Ohio Department of Natural Resources A-Z Species Guide).