Slithering, scaly snakes all look the same to those terrified of snakes, but most people could easily tell the difference between a king cobra and an anaconda. The difference between a boa and a python can be a lot harder to detect, though, especially if it involves two species that followed convergent evolutionary paths like the green tree python and the emerald tree boa, which evolved on completely different sides of the planet yet still look practically identical. While the two snakes might look similar, there are some key differences between a boa vs. a python.
Some of the most significant distinctions between boas and pythons are their average size, what areas they are native to, and their means of reproduction.
Similarities between boas and pythons
It's easy to see why boas and pythons are regularly confused for one another. They are both some of the largest and heaviest snakes in the world, and they come in an array of sizes. Both snakes are constrictors, meaning they kill their prey by wrapping around it and suffocating their catch before swallowing it.
Finally, the San Diego Zoo points out that they are both considered primitive snakes, which means they have two lungs, whereas most snakes only have one, and they both have remnants of pelvic bones and hind legs, which most snakes lack entirely. These leg remnants can be seen as two small protrusions before the tail, about where you would expect to see legs on a similar-sized lizard.
Size of boas vs. pythons
While both snakes come in an array of sizes and some snakes from each group are similar sizes, the average boa is smaller than the average python. Snake Facts says that larger boas tend to be anywhere from 4 to 12 feet long, and the only "giant snake" (meaning one that stretches more than 20-feet long) of the boa group is the anaconda, which happens to be the heaviest snake in the world.
On the other hand, there are multiple giant pythons, stretching more than 20 feet, including the longest snake in the world, the reticulated python.
Natural habitat differences
Boas can be found throughout most of the world, including Africa, Asia, North America, South America, Europe, and some Pacific islands, although most species are native to the Americas. On the other hand, pythons are strictly Old World snakes, meaning they are native to Europe, Asia, Africa, and Australia. So if a snake is native to the Americas or Pacific islands, it is a boa. If it is native to Australia, it must be a python. Snakes from anywhere else in the world could be from either family.
Of course, invasive snakes living in non-native environments do not apply to this rule. The most famous examples of this are the Burmese pythons, African rock pythons, and reticulated pythons located throughout the Florida Everglades, which were originally released by irresponsible pet owners, according to Mental Floss.
Perhaps the most surprising difference between a boa and a python is the way they reproduce. Most people imagine snakes coming from eggs, and pythons do. Boas are a little different than the average snake in that way since they almost all give birth to live young. While there are a handful of boa species that lay eggs, the chances are that if you see a snake lay eggs, it's a python — and if it gives birth to live snakes, it's undoubtedly a boa.