Biggest Snakes in the World: Meet Earth's Giant Serpents

"The question of size is a tricky one," says Jesus Rivas, a herpetologist and professor of biology at New Mexico Highlands University. Imagine if someone asked you, "What's the largest land mammal?" According to Rivas, you would "answer before hesitation" that it's the African savanna elephant.

"Nobody would start bellyaching as to how much taller giraffes are. Simply because when we mean size, mass is the determining factor," he says. "That is why I simply say anacondas are the largest snakes in the world, period."

OK, but how big do they get?

Exact measurements are hard to pin down. Green anacondas — and reticulated pythons — are incredibly strong beasts. Not only that, but a massive snake doesn't always react well to handling.

So, anybody who might want to stretch one out by hand and hold it up to an extra-long ruler sure has their work cut out for them. Rivas' book, "Anaconda: The Secret Life of the World's Largest Snake," contains some interesting anecdotes about this.

In one chapter, he describes a colleague who measured a full-grown anaconda at 18 feet (5.5 meters). To get this figure, the scientist took a piece of string, held it over the struggling reptile's back and then measured the string.

Later, Rivas himself measured the same anaconda using the exact same technique — and found the creature to be just 14 feet (4.3 meters) long. Simply by twisting its body around, the snake managed to yield two very different measurements.

Now that we have the lowdown on retics and green anacondas, let's take a closer look at some of their large cousins.

The reticulated python — or "retic" — is a marvel of nature, embodying the extremes of reptilian growth. Native to the lush rainforests of South and Southeast Asia, Malayopython reticulatus is recognized for its striking pattern, a complex mosaic of diamond shapes interspersed with intricate lines and vibrant colors.

Adults can achieve astonishing lengths: On average, adult retics typically range from 10 to 20 feet in length.

These constrictors, while nonvenomous, are formidable predators, relying on their immense strength to subdue prey, which includes a variety of mammals and the occasional bird. Retics get big enough to swallow pigs, deer — and yes, the occasional human. This comes as no surprise to Richard Shine, a biologist at Australia's Macquarie University.

In an email interview, Shine says he "encountered one individual female that was almost 23 feet [7 meters] long" while conducting research in Sumatra. "[Females] grow longer than males in both the reticulated python and the anaconda, so the biggest snake in the world (wherever she is) is doubtless a female," he notes.

In a 2005 report, another plus-sized retic — from the island of Borneo — was measured at 22 feet, 10 inches (6.95 meters) long. Fun fact about that snake: It ate a bear!

Somehow, a wild, 50-pound (23-kilogram) sun bear who'd been wearing a radio collar caught the reptile's attention. The retic swallowed it whole, collar and all. Researchers later tracked the python down for examination.

Rivas has been studying green anacondas in their natural habitat for three decades and counting.

"The largest [green anaconda] I have caught was a bit more than 220 pounds [100 kilograms]," Rivas tells us via email. "There are figures of 500 pounds [227 kilograms] that I do not doubt," he says.

Indeed, the green anaconda (Eunectes murinus) is the world's heaviest snake species. Native to South America, it thrives in aquatic environments like swamps and slow-moving rivers.

These massive constrictors, which can exceed 20 feet (6.1 meters) in length, are known for their striking green color and dark spots. Its diet includes fish, birds and even large mammals, which it overpowers with its immense strength.

Here's the rub: Green anacondas are more heavily built animals than retics.

Due to their hulking proportions, experts agree that the South American snakes can get much, much heavier than even the largest of pythons. Yet, when it comes to body length, reticulated pythons might actually have a slight edge. Rivas says there are records that suggest that, when comparing the two snakes, retics grow longer.

"The largest [green anaconda] I have measured was a bit shy of 18 feet [5.5 meters]," Rivas adds. "While I do not doubt they can grow larger, possibly 8 meters [26 feet] or more, this is far from widely accepted among [specialists]."

The King Cobra (Ophiophagus hannah) demands respect. With lengths up to 19 feet (5.85 meters), it is a true giant among its kind. This snake, native to South and Southeast Asia's dense forests, is distinguished by its chevron-patterned skin and exceptional behavior; it is notably the only snake that constructs nests for its eggs, displaying a fierce maternal protection.

The diet of the King Cobra is as remarkable as its nesting habits — it preys on other snakes, even large pythons, earning its moniker "snake-eater." Although its venom is not the most toxic, in a single bite, the King Cobra can unleash enough neurotoxins to bring down an elephant or multiple humans.

Beyond its ecological role, the King has also coiled itself into pop culture. It has inspired characters like the hypnotic Kaa in Rudyard Kipling's "The Jungle Book," and its fearsome image is central to the "Cobra Kai" dojo in the "Karate Kid" franchise, symbolizing strength and resilience.

The African rock python (Python sebae) holds the title as Africa's largest snake, with the capacity to reach lengths of up to 4.8 meters (15.7 feet). This formidable constrictor inhabits a wide range of environments across sub-Saharan Africa, from savannas to rainforests, showcasing its adaptability.

Its mottled, earthy coloration not only provides excellent camouflage amongst the African wilderness but also underscores its raw, natural beauty.

The rock python exhibits remarkable maternal instincts; females aggressively guard their eggs until they hatch, which is unusual among snakes. These pythons have a voracious appetite, able to prey on animals as large as antelopes. And due to their size and strength, they have few natural predators once they reach adulthood.

However, in some local cultures, they are hunted for their skin and meat. With a notorious reputation for being ill-tempered, encounters with humans can be perilous.

Some 58 million years ago, a gargantuan snake patrolled the rivers of Colombia. Named Titanoboa cerrejonensis, the animal swims those waters no more.

Experts aren't sure why the reptile died out. Maybe climate change did this species in — or perhaps it just couldn't compete with the big, carnivorous mammals who later arrived on the scene. What we do know is that Titanoboa was absolutely, positively gigantic.

Although nobody's ever found a complete skeleton, paleontologists have an assortment of Titanoboa fossils to go on, including ribs, backbones and pieces of skull. They paint a striking image of the long-extinct creature.

Judging by the available remains, it seems Titanoboa could have probably weighed over 1.25 tons (over 1.13 metric tons) and surpassed 42 feet (12.8 meters) in length. That would make it the largest known snake of all time. But needless to say, a lot of things have changed over the past 58 million years.

Today, we share this planet with more than 3,000 recognized snake species. Some catch live bats on the fly; some play dead; a few of them even glide down from treetops like skinny parachuters.

The Burmese python (Python bivittatus) is among the giants of the snake world. Native to the marshy regions of Southeast Asia, this species is renowned for its impressive length, which can exceed 5.5 meters (18 feet), and its considerable mass.

Despite their size, these pythons are excellent swimmers and can stay submerged for up to half an hour before surfacing for air. They are also known for their distinctive color pattern, featuring brown blotches bordered in black down the length of their bodies.

Unlike some of their other slithering pals, Burmese pythons are both predators and prey. They are apex predators in their habitat, but their young are often hunted by larger animals. These gentle giants, while nonvenomous, are constrictors, subduing their prey with immense strength before consumption.

Eunectes murinus isn't the only anaconda crawling around these days. There are three other species on record: the yellow anaconda, the dark-spotted anaconda and the Bolivian anaconda.

Adapted for a semiaquatic lifestyle in lush swamps and winding rivers, the four snakes are all native to tropical South America. They're also members of the Boidae family of snakes, which means that anacondas are technically considered boas.

"These are ... two separate evolutionary lineages of snakes, both containing some species that are small and some that are huge," says Shine. "One intriguing difference is that most boas produce live babies while all pythons lay eggs."

Geography is another point of distinction. While boas generally live in the Western Hemisphere, pythons are Old World natives. By far, the longest snake in that half of the globe is the our lengthy friend, the retic.

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.