Which Snakes Have Retractable Fangs?

Biologists divide snakes into four categories based on certain physical features, particularly the shape and construction of the fangs and teeth. Aglyph snakes have teeth instead of fangs and usually do not inject venom; opistoglyphs snakes have fangs in the rear of their mouths; proteroglyphs, like cobras, are "front-fanged" snakes; while solenoglyph snakes are the deadliest . Solenoglyphs have fangs that retract and extend as they open and close their mouths and often deliver deadly poison when they bite.

Puff Adder

• Puff adders are one of the most deadly and feared African snakes. Measuring about three feet long for an adult, these snakes have fangs that spring out from the roofs of their mouths when they strike. This allows for especially long fangs of up to almost three-quarters of an inch that puncture skin deeply upon contact. The venom of the puff adder causes necrosis, pain, nausea and eventually death if left untreated. Puff adders are also one of the most common African snakes.

Cottonmouth

• Cottonmouth snakes, also known as water moccasins, live in swampy areas of Florida, Louisiana and the southern United States in general. The cottonmouth is a type of pit viper, due to the presence of two heat-sensing organs on its head. Cottonmouths can grow to be several feet long and are aggressive when disturbed. Cottonmouths have retractable, hollow fangs that deliver highly toxic venom deep into animal tissue.

Rattlesnake

• Rattlesnakes, with triangular heads and a distinctive warning rattle, pose a threat to residents of the southwestern United States. Rattlesnakes hibernate during the winter. They emerge in the spring and normally hunt during the night hours, sleeping or hiding when it's sunny. Rattlesnakes give birth to live young, unlike many other varieties of snake. Their fangs normally fold up into their mouths, lying dormant until the snake strikes. During a strike, the fangs pop up and outwards, delivering a dangerous and painful dose of venom. Rattlesnake venom can be fatal if not promptly treated with anti-venom.

Stiletto Snake

• Stiletto snakes live in Africa. They deliver toxic venom with each bite and have a unique mechanism for striking prey. These snakes normally have retracted fangs but when they strike the small fangs snap outwards, puncturing the snake's mouth and embedding themselves into the victim's tissue. The venom of stiletto snakes is painful and poisonous, but rarely fatal. In fact, this snake is rarely aggressive when encountered and prefers to spend its time wending around underground tunnels.