Snake Anatomy 101: What Makes a Snake, Inside and Out

Yara Simón
·5-min read

Unlike most other animals, snakes do not have limbs to help them get from one place to another. Instead, they slither — but there's a little more to snake anatomy than how they move. Finely tuned for survival, snakes have specialized anatomy that let them thrive in diverse environments.

External Anatomy of a Snake

First things first, let’s talk about what you can see on the outside of a snake. These external features help snakes navigate their environment, find prey and defend themselves.

Forked Tongue

One of the most recognizable features of snakes is their forked tongue. Snakes flick this unique organ in and out of their mouths, using it to collect particles from the air.

The forked shape helps them pick up chemical signals from both sides of their environment, which they process using a special organ called the Jacobson’s organ (located on the roof of their mouth). This allows them to detect the "scent" of their prey items, as well as navigate and find mates.

Heat-sensing Organs

Found on the faces of species like pit vipers, these organs let snakes detect warm-blooded prey, even in the dark. They can "see" like a thermal camera.

Spectacles

These transparent scales, or spectacles, cover snakes' eyes.

Nostrils

Located on their heads, nostrils help snakes breathe and detect odors.

Scales

Snakes have a few types of scales, including:

  • Dorsal scales: Located on the backs of snakes and used for protection and movement

  • Ventral scales: Larger, specialized scales on the underside of the snake

  • Subcaudal scales: Found on the underside of the tail

Cloaca

An external opening located near the base of the tail, the cloaca is for excretion and reproduction.

Tail

This is the portion of the snake's body after the cloaca, often tapering to a point. Some snakes, like rattlesnakes, have specialized features like a rattle at the tip.

Teeth or Fangs

Nonvenomous snakes have small, recurved teeth, while most venomous snakes have grooved or hollow fangs for delivering venom.

Nuchal Ridge

The ridge along the back of the head or neck that is prominent in some species.

Internal Anatomy of a Snake

Unlike most animals, snakes have elongated bodies, with their organs stretched out.

  • Glottis: Located at the front of the mouth, this allows the snake to breathe even while swallowing large prey. The glottis can move to the side to keep the airway open.

  • Lungs: Instead of having two equally sized lungs, a snake's right lung is the primary lung, while the left lung is either much smaller or absent altogether. This unique feature allows snakes to have more room in their bodies for large prey items.

  • Digestive system: After swallowing prey whole, food travels through the esophagus and into the stomach, where digestion begins. The small intestine absorbs the nutrients before it passes through to the large intestine, which processes waste.

  • Jaws: Snakes have a highly flexible lower jaw that doesn't fuse like ours. This flexibility allows them to "unhinge" their jaws, stretching their mouths wide enough to swallow prey much larger than their head. Each side of the lower jaw moves independently, helping the snake work its prey down its throat in a kind of "walking" motion.

  • Skull: Snakes have highly flexible skulls that allow them to swallow prey much larger than their heads.

  • Vertebrae: Snakes have a large number of vertebrae (up to 400 in some species), which provide support and flexibility.

  • Ribs: Snakes have ribs extending from nearly every vertebra, providing protection and aiding in movement.

  • Muscular system: Snakes have powerful muscles that run along their bodies, helping them slither, constrict prey and swallow food. The muscles are arranged in segments corresponding to the vertebrae and ribs.

  • Brain: Snakes have a small brain compared to their body size, but it can control essential functions like movement, feeding and sensory processing.

  • Spinal cord: Running the length of the body, the spinal cord transmits signals between the brain and body, coordinating movement and reflexes.

  • Nerves: Nerves branch out from the spinal cord to control various muscles and organs.

  • Heart: The snake's heart is closer to the head, around one-quarter down the length of its body. It has three chambers: two atria and one ventricle.

  • Blood vessels: The snake's circulatory system works efficiently with its long body, supplying blood to the muscles and organs as necessary.

  • Kidneys: Snakes have two kidneys, which filter waste from the blood. Unlike mammals, snakes have elongated kidneys, positioned one behind the other along the body.

  • Ureters: These tubes carry waste from the kidneys to the cloaca.

  • Reproductive system: Male snakes have hemipenes, paired reproductive organs that are inside the base of the tail. Female snakes have paired ovaries that produce eggs and oviducts through which the eggs travel.

  • Jacobson's organ (vomeronasal organ): Located on the roof of the mouth, this organ detects chemical signals in the environment. The forked tongue gathers particles and delivers them to this organ.

  • Lymphatic system: Snakes have a lymphatic system similar to other vertebrates, which helps in immune response and fluid balance.

What Distinguishes Snakes From Other Reptiles?

One of the most obvious differences between snakes and other reptiles is their lack of legs. Snakes use their muscles and scales to slither through their environment. This lack of legs also contributes to their elongated shape and specialized anatomy.

Snakes also do not have external ears. While many reptiles have external ears that help them hear sound waves, snakes only have an internal ear, which picks up vibrations from the ground. This ability allows them to "hear" in a completely different way from other reptiles, relying on their jawbones to detect movement and vibrations.

Another key difference lies in their feeding habits. Many reptiles, like lizards, bite off chunks of food or chew, but snakes swallow their prey whole. This is where the flexibility of their lower jaws comes in handy, allowing them to ingest prey much larger than their heads. The specialized set of teeth in their upper jaw grips prey as they work it down their throat.

And finally, many species of snakes can thrive in specific environments. For example, the hognose snake uses its uniquely shaped nose to burrow into loose soil, while other snakes have evolved labial pits to sense heat. These adaptations, along with the flexible anatomy of their jaws and organs, make snakes uniquely equipped for survival compared to their reptilian cousins.

We created this article in conjunction with AI technology, then made sure it was edited and fact-checked by a HowStuffWorks editor.

Original article: Snake Anatomy 101: What Makes a Snake, Inside and Out

Copyright © 2024 HowStuffWorks, a division of InfoSpace Holdings, LLC, a System1 Company

Latest stories

  • The Mangrove Snake Is a Tree-dwelling Hunter

    Slither into the world of the mangrove snake — one of the coolest reptiles in the mangrove forests of Southeast Asia. These snakes are not only sleek and stunning with their black bodies and bright yellow bands, but they’re also equipped with some fascinating adaptations that make them incredible hunters.

  • 10 Cobra Snake Species to Keep Out of Striking Distance

    Cobras are some of the most venomous snakes on the planet, also known for their intimidating hoods and swift strikes. But while their venom and striking power make them feared by many, the role of the cobra snake in ecosystems is invaluable, from controlling rat populations to maintaining a balance among predators.

  • 11 Racer Snake Subspecies That You Have No Reason to Fear

    The racer snake is sleek and swift. Despite their sometimes intimidating speed, mostly harmless to humans. You may confuse racers for other snakes because of their color, but they have unique behaviors and characteristics that make them stand out.

  • Brits unknowingly risking £20,000 fines if they remove common plant from their garden

    Brits may not realise an autumn overhaul in their garden could cost them thousands in fines if they aren’t knowledgeable about what plants they have

  • Beloved grizzly bear killed by car near Yellowstone

    A beloved grizzly bear which drew crowds of visitors to a national park has died after being hit by a car.

  • Keep your eyes peeled as Worcestershire seller gets 98x face value for 50p coin

    The Atlantic salmon 50p coin, which is the most rare, has sold for £49 on eBay with a seller from Malvern, Worcestershire taking home 98x the face value.

  • An Indian village went from hunting Amur falcons to being their biggest protectors. Here’s how conservationists can harness the power of persuasion

    A global media campaign, spearhaded by charity Conservation India, publicised a short film about the Amur falcon massacre and instigated huge change.

  • Rare birth of critically endangered lemur at Cotswold Wildlife Park

    Cotswold Wildlife Park has achieved breeding success with one of the most endangered lemurs in Madagascar.

  • Greenland further extends detention of anti-whaling activist Paul Watson

    A court in Greenland has once again decided to extend the custody of anti-whaling campaigner Paul Watson, until November 13, while Denmark considers a Japanese extradition request. A Greenland court on Wednesday extended the detention of anti-whaling activist Paul Watson for three more weeks, pending a decision on his possible extradition to Japan for an altercation with whalers in 2010.This marks the fourth extension of his detention since Watson was arrested in July in Nuuk, capital of the Dan

  • No mistaking fabled 'king' after close encounter in India

    An Indian Forest Service employee this week shared an image showing a large snake pausing in a clearing with its head and neck raised in a classic cobra posture. Parveen Kaswan stated via X: “This beauty. Let’s see who can guess t

  • Grand Teton grizzly bear No. 399 that delighted visitors for decades is killed by vehicle in Wyoming

    A famous grizzly bear beloved for decades by countless tourists, biologists and professional wildlife photographers in Grand Teton National Park is dead after being struck by a vehicle in western Wyoming. Grand Teton and U.S. Fish and Wildlife Service officials said they had no further information to release about it. Each spring, wildlife enthusiasts eagerly awaited her emergence from her den to see how many cubs she had birthed over the winter — then quickly shared the news online.

  • Dozens of swans, geese and other wild birds found dead in London canal

    The government is investigating the alarming number of bird deaths, the cause of which has not yet been confirmed

  • The African House Snake Will Love You for a Humid Home

    The African house snake is a small, nonvenomous snake native to southern Africa, often kept as pets due to its docile nature and ease of care. If you're into reptiles, you may have heard of them, but if not, you're in for a treat!

  • Climate change a worry for Greece's hungry butterflies

    STORY: In a zoo outside Greece's capital Athens, thriving butterflies feed on orange slices. That's because this environment is free from the hazards of climate change currently threatening populations in Greece and across the world.Antonis Balas works at the Attica Zoological Park.“It severely affects their reproduction and the duration of their lives. So, we see that, as the climate, in their natural environment, changes, their lifespan decreases.”Greece is home to some 237 species of butterflies.But warmer temperatures are making their lives harder.Food is becoming scarcer, and flowering periods are getting shorter.Experts also suspect the butterflies may be getting smaller.Agronomist Konstantinos Anagnostellis is part of research project called MEIOSIS by the Greek University of Ioannina.Their goal is to model how the body size of butterflies has decreased in response to climate change.“Climate change is impacting butterflies due to rising temperatures, as they are ectothermic and diurnal organisms that rely on temperature to perform essential activities such as mating, reproduction, growth, development and feeding.”Anagnostellis also says the heat is driving butterflies to cooler areas where there is less food.And that worsening wildfires are further limiting their access to it, because of the loss to grasslands.The problem is echoed globally, including in Mexico and Britain where numbers of some species have declined sharply.

  • A grizzly bear that delighted Grand Teton visitors for decades has been killed by a vehicle in Wyoming

    A famous grizzly bear beloved for decades by countless tourists, biologists and professional wildlife photographers in Grand Teton National Park is dead after being struck by a vehicle in western Wyoming.

  • Why polar bears have been left unable to walk

    Polar bears are struggling to walk because climate change is causing ice blocks to form around their feet.

  • How a nearly extinct crocodile species returned from the brink in Cambodia

    A tiny snout poked out to widen the crack of the slowly shattering eggshell. The Siamese crocodile was taking its time, lagging others that had already wriggled out, chirping, into the sand. Hor Vichet, a zookeeper at the nonprofit Fauna and Flora's breeding center for the critically endangered reptiles in Cambodia’s Phnom Tamao, broke the rest of the shell.

  • The Glass Lizard, aka Glass Snake, Makes Its Tail Shatter

    Today, we’re diving into the world of the glass snake, more commonly known as a glass lizard. They aren’t actually snakes at all; they’re several species of legless lizard. That's right, glass lizards look an awful lot like snakes, but they have some key differences that set them apart.

  • In pictures: Thousands of birds put on dramatic spectacle

    Photographers have captured images of one of the Snettisham Spectacle at RSPB Snettisham in Norfolk.

  • Look out for this 'very rare' 50p coin as it sells for more than £100 on eBay

    Check your change and the back of your sofa for this Atlantic salmon 50p coin as it has sold for £107 on eBay this week.