Remember way back when I did the Dimetrodon entry and pointed out that it was weird for reptiles to have different types of teeth? Snakes are a kinda big exception that I may have forgotten to mention. Although venom only evolved once in snakes, the short fangs of elapids and long fangs of vipers are clearly differentiated teeth.
There are also several other snakes that don't really fit into either 'big' category of venomous snake. These snakes are typically dubbed 'rear-fanged venomous' (or 'ophisthoglyphous') - they have fangs, but they're set too far back in the mouth to be of any real use. In short, they have to push prey to the back of their mouths to inject the venom.
Rear-fanged snakes tend to be weird. I do not just mean in regards to their teeth. (As a refresher, the last rear-fanged snake we looked at was Ahaetulla nasuta, one of the bases for Snivy.)
The Western Hognose (Heterodon nasicus) is one such rear-fanged snake. Its venom (which is harmless to humans, BTW) is betrayed by its appearance; like many vipers, it has keeled scales and a stout body. Other names for it include "puff adder," "blow viper," "spoonbill snake," and "faux viper" if you must have some class. It lives across many states of the U.S. (and some parts of Canada and Mexico) with no problems, but is considered endangered in Iowa and threatened in Illinois and South Dakota. (This is probably why I have NEVER seen them for sale in IL, despite being docile and popular in captivity.)
It is immediately obvious where the Western Hognose got its most common name from. The scales on this snake's nose form a little 'shovel' that allows it to vanish beneath the ground the moment a predator approaches. This is the least shocking of its defensive behaviors.
First, if approached head-on, a hognose will inflate its body and hiss loudly. Closed-mouth strikes are common. The hognose may also mimic a cobra amazingly well, flattening its neck out into a hood. Given that cobras are native to Asia and Africa and hoggies are native to North America, one cannot help but wonder where this little snake got the idea. Too many biker tattoos, perhaps?
This hognose has ceased to be. It's expired and gone to meet its maker. This is a STIFF. Bereft of life it rests in peace. If it had hands it'd be pushing up daisies. THIS is an EX-SERPENT!
Kidding. Hognose snakes, along with a few others, are experts at playing dead. Besides looking like roadkill and staying relatively still, they will go so far as to make their mouths bleed. They are really a bit too forceful about it; if overturned, a hognose playing possum will turn itself back over.
The Western Hognose was once cited by BHB as one of their three 'money snakes,' the other two being ball pythons and corn snakes. Aside from their interesting defensive habits and 'venomous' nature, they are very hardy snakes that accept thawed mice readily. Captive breeding has also led to a few interesting color morphs, among them two albino variations and an 'anaconda' morph. If they're legal where you are, you can brag that you have a venomous snake. People will believe you after the cobra display.
Also, have a psychedelic hog.