Fangs developed a series of times to give us some of the most venomous predators of the planet.
"Fangs" are defined as specialized teeth used for venom deliverance in animals. In snakes, three types of fangs fit the three venomous groups currently classified. These groups are the Vipers, Elapids, and Colubrids and their fangs are classified as Solenoglyphous, Proteroglyphous, and Opisthoglyphous. Each of these groups are separated by the unique design and the method of how they inject venom into their prey.
Venomous snakes actually have the ability to control their venom, meaning they can deliver what's called a "dry" bite if they want to. This is typical when they are striking out of defense instead of a predator drive to kill. This suggests venom was designed for feeding and not defense. As snakelets, they may have less precision in venom control because they could still be "learning" their own mechanisms. Venom is essentially a complex and unique mixture of saliva, which comes from special glands in the head. Venom flows through fangs to immobilize and consume prey.
Viperids And Solenoglyphous Fangs
The most advanced Fangs evolved once and set the Vipers a part from all other snake groups and are called Solenoglyphous fangs. Fossils suggest that these fangs have changed little since they evolved around 40 million years ago, and they can be found in all modern Viper species. These fangs can be described as hollow, foldable, specialized teeth designed for maximum envenomation, and are strikingly similar to hypodermic needles. The Viperid Fangs are connected to venom glands which can be controlled by the Vipers for maximum potency in the quickest bite possible. Solenoglyphous fangs are long and tubular, assisting in holding prey in place and delivering deep wounds. When the Viper strikes, the hollow core of the fang flows venom from the glands through a slit like opening in the tooth. These fangs regularly shed every couple of months. Solenoglyphous fangs fit into a pocket of bone in the jaw which allows them to fold up into their mouths when not in use. This feature is also used when feeding and allows the fangs "walk" prey down their throats (whole). These fangs are the most accurate, dangerous, and specialized anatomical forms which have placed Vipers with the most advanced venom delivery system on Earth.
photo courtesy of luke verburgt
Close up of a puff adder (Bitis arietans) Solenoglyphous fang.
Modified Solenoglyphous Fangs are found in the family Lamprophiidae, subfamily Atractaspidinae which include mole vipers, burrowing asps, stilleto snakes, harlequin snakes, and African dwarf garters. In some species, these fangs are movable, but do not fold up in the same way as true Solenoglyphous fangs do. The fang morphology of these groups are similar to Vipers since they share a common ancestor around the same time period.
Proteroglyphous Fangs And Elapids
The next form of specialized fangs are found in the Elapid family which include sea snakes, cobras, and others. These fangs are usually fixed, which makes them many times shorter than the average Solenoglyphous fang. The venom is still delivered from a gland in the head and through a slit like opening in the tooth, and some snakes (like the spitting cobra) have developed modifications to increase the velocity at which venom is injected. Unlike vipers, more than one fang can sit in the tooth pockets, which helps Elapids strike and hold on to their prey to deliver the maximum amount of venom possible (versus the quick strikes of Vipers). Some Elapids, many of which are very dangerous, have partially moveable Proteroglyphous fangs. Some Elapid species, like the fish egg eating sea snakes, have secondarily lost their fangs and venoms, again suggesting that venom was evolutionarily developed for diet instead of defense.
photo courtesy danny stiene
Proteroglyphous fangs of a Cobra.
Opisthoglyphous Fangs And Colubrids
Colubrids are a thrown together group of snakes that includes too many to list, ranging from hognoses to barons racers, to the deadly boomslang. It seems that Herpetologists are constantly debating the classification of this group, and it may always need clarification. For now, we describe the Colubrids as possessing Opisthoglyphous Fangs who are commonly described as "rear-fanged" species. These fangs are located towards the back of the mouth, and require the snake to literally "chew" on prey to deliver the venom. Although this may be seen as the least effective form of fangs, some of the world's most deadly species fit this category like the twig snakes and boomslangs. It seems that this fang form has evolved multiple times, and more research is needed to better understand the venom capacity of these species'. While two are well known to be dangerous to humans (twigsnake/boomslang), many others have little to no research on their potency in regards to humans. Most are compared to mild venoms (like bee stings) which are not fatal to humans, but caution should always be exercised when handling rear fanged species.
photo courtesy jiri dubislav
Rear-fanged species showing Opisthoglyphous fangs.
Venom Evolution
The need for venom evolved to help these reptiles survive. Throughout the eras, reptiles have been adapting and evolving to specialized habitats and diets, which has helped design fangs. The advanced saliva mixtures that lead to various painful venoms has placed venomous snakes into unique categories of their very own. Understanding these details can lead to a greater understanding and preservation of these beautiful and potent predators.
