If you’ve ever wondered if snakes can grow arms, you’re not alone! While the vast majority of snakes have no limbs at all, there are a handful of rare snake species that possess arm-like appendages.
If you’re short on time, here’s a quick answer to your question: There are a few very rare species of snakes, such as the African burrowing python and the armored blindsnake, that possess small vestigial limbs resembling arms.
These appendages are thought to be evolutionary remnants from lizard-like ancestors.
In this comprehensive article, we’ll take a closer look at these mysterious limbed snakes. We’ll cover what species have arms, what their arm-like appendages look like and function as, why these snakes retained their ancestral arms while most snakes lost theirs entirely, and more.
Snake Species with Arms
African Burrowing Python
The African burrowing python (Calabaria reinhardtii) is a nonvenomous snake species found in tropical West and Central Africa. They get their name from their stout bodies and shovel-like heads used for burrowing underground.
But their most unique feature are the small, claw-like spurs on either side of their cloaca – essentially rudimentary hind legs (making them one of the few known “four-legged” snake species).
These spurs likely evolved from the vestigial remains of the pelvis and legs of ancestral lizards from which snakes descended over 100 million years ago. Though non-functioning for walking, scientists theorize the spurs may aid in anchoring partners during mating.
Average adults reach 2 to 3 feet long and feed primarily on rodents, lizards, smaller snakes, eggs, and amphibians.
Armored Blindsnake
The armored blindsnake (Anilios hamatus) is a tiny (4 to 8 inches long) fossorial (burrowing) species residing in arid sections of Western Australia. As with other blindsnakes, their eyes are greatly reduced in size and functionality.
But this species exhibits another anatomical peculiarity – possession of visible “arms” formed from rib segments extending laterally from their midsection.
These protruding ribs anchor muscles likely assisting their underground tunneling and movement. Their diet consists of termites, ant larvae, and pupae excavated from nests. Beyond skeletal support, the rib-like arms also provide protection, leading to their “armored” common name.
Documented as the only snake species with such lateral protrusions of the ribs.
Mexican Mole Lizard
Though named a “lizard”, the Mexican mole lizard (Bipes biporus) is actually an amphisbaenian – a legless burrowing reptile sharing a common ancestor with lizards and snakes. Their cylinder-shaped bodies and shovel-like heads are adapted for subterranean living.
But they also sport a pair of short forelimbs reminiscent of small arms.
These slender pentadactyl (five-digited) limbs are complete with claws and full arm musculature plus shoulder girdles anchoring them to the body. The “arms” assist in digging tunnels through loose soil and likely provide sensory input on surroundings.
Their native habitat spans central Mexico through Guatemala where they feast on invertebrates and larvae. Though small and hidden, the mole lizard represents another fascinating squamate reptile bearing appendages.
| Species | Arm/Limb Type & Function |
|---|---|
| African Burrowing Python | Vestigial leg spurs – mating anchors |
| Armored Blindsnake | Protruding rib segments – muscle anchors for digging |
| Mexican Mole Lizard | Forelimbs with claws – sensory input & digging |
According to reptile conservation groups (Global Reptile Conservation, Saurian Enterprises), these remarkable squamates deserve more scientific study and habitat protection efforts. Though rare and lesser known, their unique anatomies provide insight into snake and reptile evolution.
Appearance and Function of Snake Arms
Vestigial Limbs
Some snakes like pythons and boas have small vestigial hind limbs known as “spurs” that are remnants of the legs their ancestors had. These spurs are located on each side of the cloaca and contain bones, cartilage, nerves, muscles, and blood vessels, though they serve no purpose for locomotion.
They represent evolutionary leftovers from when snakes had fully functioning legs and are similar in structure to the back legs of their nearest relatives, monitor lizards.
The vestigial limbs on snakes are very small, often less than an inch long, and are covered by scales. They usually have a claw or nail at the end. Sometimes the limbs are so reduced that only the claws remain. These tiny snake legs are non-functional and simply hang limply at the snake’s sides.
Researchers believe the reduced size of snake legs reflects evolutionary loss of function as their ancestors adapted to a burrowing lifestyle. With their long, limbless bodies, snakes gained an advantage in being able to swiftly tunnel through the ground.
The limbs eventually shrank away since they were no longer being used.
Spurs for Mating and Digging
While vestigial limbs on snakes are non-functional remnants, some snakes like boas and pythons have larger, more developed spurs on their sides that serve purposes related to mating and burrowing.
During mating, male snakes use these larger spurs to anchor themselves to the female snake, grasping her body between their spurs and cloaca. This allows for easier transfer of sperm. The spurs essentially function as temporary “legs” to gain leverage on the female.
Some snakes also use their spurs for traction while burrowing underground. By pressing the spurs against tunnel walls, they can more easily push themselves forward through tight spaces. So while they can’t walk with their spurs, some snakes do get functional use from them.
Leftovers from Lizard Ancestors
The vestigial limbs and spur structures seen on some snakes provide evidence that snakes evolved from four-legged reptilian ancestors. Researchers believe snakes descended from lizards in the Cretaceous period about 100-125 million years ago.
Primitive snakes like pythons and boas retain these remnants of hind limbs because they branched off the evolutionary tree earlier. Other more recently evolved snake species do not have leftover leg structures since their limbless form developed later.
When comparing snakes, the presence and size of limbs indicates how ancient or recent in origin a species is.
Ancient lizards had four functioning legs. But over evolutionary time, as some lizards adapted to underground environments, they lost use of their limbs. Snakes retain traces of this legged ancestry even though legs are absent in their present-day form.
The spurs and claws found on some snakes offer a peek into their evolutionary past.
Evolutionary History and Advantages
Shared History with Lizards
Snakes with arms, known scientifically as vipers, share a common evolutionary ancestor with lizards. Over 100 million years ago, a group of lizards began adapting to life underground by developing long, limbless bodies ideal for burrowing.
These primitive snakes still retained small remnant limbs, revealing their connection to surface-dwelling lizards.
Advantages for Burrowing and Mating
The small forelimbs of vipers provide advantages for their underground lifestyle. The short “arms” help them maneuver through tight burrows and tunnel systems, allowing vipers to hunt prey and avoid predators in their subterranean homes.
Additionally, male vipers use their limbs to grip females during mating to align their reproductive organs. So although reduced, the arms remain useful for critical survival tasks.
Gradual Limb Reduction Over Time
As these burrowing lizards continued to adapt, their limbs gradually reduced in size over millions of years. According to fossil evidence summarized on UC Berkeley’s Understanding Evolution website, the forelimbs shrank before the hindlimbs, likely because forelimbs were less useful for underground movement.
Modern snakes retain tiny vestigial pelvic “hips” and rear leg bones, representing remnants of once larger hindlimbs.
While complete limb loss provides an advantage for today’s burrowing snakes, viper ancestors retained small forelimbs just long enough to aid their initial transition to an underground niche. Their residual arms allowed a gradual adaptation, preventing any sudden loss of critical functionality.
Conclusion
While nearly all snakes lost their ancestral limbs over millions of years of evolution, a few rare species retained vestiges of arms and legs. These arm-like appendages likely provided advantages for certain snakes in specialized environments, helping them dig, grasp mates, and move through tight spaces.
So while spotting a snake with arms remains an extremely uncommon occurrence, their existence provides a glimpse into snakes’ distant lizard and quadruped ancestors. If you happen to encounter one of these limbed oddities in the wild, consider yourself privileged to witness evolution’s living relic!
