Snakes are renowned for their ability to swallow large prey whole, thanks to their incredibly flexible jaws. If you’ve ever wondered just how wide a snake can actually open its mouth and unhinge its jaw, you’re not alone.
If you’re short on time, here’s a quick answer to your question: some snakes like pythons and anacondas can open their mouths wide enough to swallow prey much larger than the size of their own head!
In this comprehensive guide, we’ll explore the incredible anatomy that allows snakes to open their mouths so wide, look at exactly how wide different snake species can open their mouths, and compare just how their jaw-opening abilities stack up against one another.
What Makes It Possible for Snakes to Open Their Mouths So Wide?
Their Lower Jaws Are Divided Into Two Halves
A key anatomical feature that enables snakes to open their mouths so wide is that their lower jaws are divided into two separate halves that are only joined by an elastic ligament. This allows each side of the lower jaw to move independently and stretch apart much further than our human jawbones allow.
According to the University of California Museum of Paleontology[1], the lower jaws of snakes are connected by an elastic ligament rather than being fused into one solid bone. This gives each half of the lower jaw great flexibility to slide away from the other half very widely when needed, such as to swallow larger prey items.
They Have Stretchy Ligaments and Muscles Connecting Their Jaws
In addition to their bifurcated lower jaws, snakes also possess extremely stretchable ligaments and skin around their mouths and throats. According to Britannica[2], the skin and muscle connecting a snake’s upper and lower jaws allow them to open their mouths nearly 180 degrees.
There are also accordion-like muscles and ligaments connecting a snake’s lower jaws to the sides of its throat. These specially adapted connective tissues stretch like an elastic band when the snake opens its mouth wide to swallow larger prey.
Their Skull Bones Are Only Loosely Connected
The bones of a snake’s skull are also quite loosely connected, adding to their jaw flexibility. According to ThoughtCo[3], a snake’s skull contains kinetic joints rather than rigid fused sutures. This allows the bones to bend and move more freely as the mouth opens wider.
In addition, snakes have extra space between their jaw joints that serves as “expansion room” enabling further gape extension. Their lower jaws can slide forward on their skull when swallowing prey, essentially dislocating and disengaging the quadrate bone that forms their upper jaw joint.
How Wide Can Different Snake Species Open Their Mouths?
Pythons and Anacondas: Over 150 Degrees
Two groups of nonvenomous constrictors, pythons and anacondas, can open their mouths incredibly wide – over 150 degrees! This allows them to swallow large prey whole, including pigs, deer, caiman and more.
According to the University of Michigan Museum of Zoology, reticulated pythons have been documented with mouth stretches over 160 degrees.
Boas: Up to 270 Degrees
Another family of nonvenomous snakes, the boas, takes jaw flexibility even further. Several species, including rainbow boas and rubber boas, have been measured with mouth openings close to 180 degrees.
Most impressive is the rosy boa, which has been documented with mouth stretches over 270 degrees, allowing them to swallow prey nearly as thick as their own body!
Egg-Eating Snakes: Nearly 160 Degrees
Egg-eating snakes have specialized jaws and teeth for cracking into eggshells. According to a 2015 study, they can dislocate their jaws to expand them up to 158 degrees. Researchers believe egg-eating snakes evolved this trait by natural selection to take advantage of an abundant food source that few other snake species eat – bird eggs.
Vipers: Up to 122 Degrees
While not quite as wide as pythons and boas, venomous vipers are also capable of impressive mouth stretches. Studies on species like rattlesnakes and bush vipers have measured maximum gapes between 100-122 degrees.
Their flexible jaws allow them to consume proportionally large rodent and bird prey relative to their head size. However, they use venom more than girth to immobilize prey larger than their head width.
World Records for Snakes With the Widest Gape
Reticulated Python: Widest Gape Ever Recorded
The reticulated python has set the record for the widest gape ever documented in a snake. These enormous constrictors have been measured with gapes exceeding 150 degrees.
According to the University of California Museum of Paleontology, reticulated pythons can open their mouths so wide that they can swallow prey items up to a quarter of their own length![1] With adult reticulated pythons averaging over 20 feet in length, that means these snakes can swallow prey up to 5 feet long after opening their mouths exceptionally wide to maneuver the large items down their throat.
Green Anaconda: Can Open Its Mouth Nearly 180 Degrees
While the reticulated python may have the widest documented gape, the green anaconda can open its mouth almost as wide, to nearly 180 degrees. This incredible flexibility allows them to swallow very large prey whole after constricting them.
National Geographic explains that a green anaconda’s stretchy ligaments allow it to open its mouth and throat wide enough to swallow fairly large animals like deer, pigs, capybara, caimans, and sometimes even jaguars![2] Their mouths can open nearly 180 degrees to allow the consumption of such challengingly large meals.
African Egg-Eating Snake: Gape Over 130 Degrees
While not as wide as the reticulated python’s record-setting gape, African egg-eating snakes can still open their mouths exceptionally wide compared to most snakes, over 130 degrees.
This astonishing flexibility aids them in their specialized diet – large bird eggs. By unlocking their jaw to widen their mouth over 130 degrees, they can consume entire large eggs whole, including those of chickens, guinea fowl, and other sizeable species.[3] Their unique skulls and jaws allow them to gape wider than most oher snakes to accommodate such sizable oval meals.
Conclusion
A snake’s incredible ability to open its mouth so incredibly wide is made possible by the remarkable flexibility and adaptations in their skull and jaw anatomy. While not all snakes can open their mouths as wide as pythons and anacondas, even small snakes have some degree of expandable tissue in their jaws to help them swallow larger prey.
The giants of the snake world like reticulated pythons and green anacondas hold records for having awe-inspiring mouth-opening capacities well over 150 degrees. Their extreme jaw flexibility allows them to tackle prey many times larger than their head size, showcasing the amazing evolution of snakes as predators and consumers.
