Any of three or four species (genus Heterodon, family Colubridae) of harmless North American snakes named for their upturned snout, which is used for digging. When threatened, they flatten the head and neck, then strike with a loud hiss, but rarely bite. If their bluff fails, they roll over, writhing, and then act dead, with mouth open and tongue lolling. They eat chiefly toads and frogs. Heavy-bodied and blotchy, they are usually about 24 in. (60 cm) long. Though not adders, they are sometimes called puff adders or blow snakes.
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