Where Is a Snake’s Heart? 5 Amazing Facts About Their Anatomy

Written by Sofia Fantauzzo
Published: October 23, 2023
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Snake anatomy looks pretty different to the anatomy of animals we’re most used to seeing. Essentially, a snake is one long tube packed full of essential organs like lungs, a stomach, and a heart. The exact position of a snake’s heart depends on whether it is a tree-climbing (arboreal) snake or a ground-dwelling snake.

In arboreal snakes, the heart is closer to the head, about one-quarter of its body length away from its head. In ground-dwelling snakes, the heart is usually a bit further away from the head, around a third of the way down its body from the head. But that isn’t always the case — some large boas also keep their hearts closer to their head.

While the heart might not be in a strange position, there are a few intriguing details about the anatomy of snakes. Here are six more traits that might challenge your understanding of snakes:

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1. Most Snakes Only Have One Lung

Snakes might be born with two lungs, though only one is functional in most species. This is most often the right lung. It’s called a “simple lung” and the other, non-functioning one is called a “vestigial lung.” Sometimes, a second lung is completely absent. The exceptions are pythons and boas, which have two functioning lungs. The large lung can take up a lot of space in a snake. It may even span the length of its heart to the bottom end of its body.

Snakes also lack a diaphragm, which is a muscle beneath the lungs that contracts and helps many animals breathe. Since snakes don’t have this organ, they move their rib muscles to pump the lung to breathe.

2. Snakes Have Over 300 Bones

Real anaconda snake skeleton diorama

Large snakes, like pythons or anacondas, can have over 1,800 bones!

©El Arquitecto de Huesos/Shutterstock.com

Compared to the 206 bones humans have, 300+ is quite a large number. Since snakes need to slither, the more bones they have, the more points of articulation they have, too. These make it easier for them to move around and have structure in their bodies. Since snakes expand their jaws and their bodies to take in prey, they need to have a lot of flexibility in their ribcage.

Strong bones help crush and strangle prey along with their muscular bodies, so snakes put all of these extra bones in their anatomy to work to effectively survive without limbs!

3. A Snake’s Heart Has Three Chambers

Mammal and bird hearts have four chambers. Two of these chambers receive blood into the heart (atria) and two pump blood out of the heart (ventricles). Ventricles are more muscular since they actively pump blood out of the organ.

A three-chambered heart has to work a bit differently. There are two atria and one ventricle. Snake hearts are not able to pump out as much blood since there is only one ventricle, but this is not a big disadvantage.

As cold-blooded animals (also known as “ecotherms“), snakes have slow metabolisms. A slower metabolism allows for lower oxygen demands in the blood. Therefore, snakes don’t have as high of a need to pump a lot of oxygenated blood through the body to power cellular processes.

4. Snakes Can Take Weeks to Digest Their Meals

King Crobra eating food

Snakes can move their lower jaw left and right to help work the food into their esophagus.

©somdul/iStock via Getty Images

Eating meals as large as snakes do definitely calls for some changes to their bodies. Snakes can eat meals that weigh as much or more than they do! Naturally, digestion is a serious feat for these ectothermic slithery creatures.

First, they have a specialized, flexible, skull. The upper portion is split in two or four pieces and the lower jaw is in two. They’re connected by very flexible ligaments. Their esophagus can be up to half the length of their body and has many folds to help with the passage of large prey. Snake anatomy is well-adapted to what their bodies must go through when they consume their meals.

Digestion can take multiple weeks to digest completely, depending on the size of the meal and their body temperature. During this time, the snake’s metabolism can increase up to 45 times its normal speed and maintain this during digestion. It takes a lot of time and energy for an animal that cannot produce its own body heat to break down large meals. While a snake is digesting, all the energy it can muster is diverted to this process. This means they’re not very physically active during this time. If you’ve ever kept large snakes as pets, you might have observed them becoming “lazy” after eating for a few days.

Fortunately for snakes, that means they can go long periods between meals without dying of starvation.

5. Snakes Smell Through Their Tongue

A head shot of a coastal taipan flicking its tongue

The forked tongue can pick up two different odor molecules and process them at the same time.

©iStock.com/ROBERT STYPPA

The telltale flickering of a forked tongue is an image that immediately comes to mind when one thinks of snakes. Snakes do have nostrils, but they’re used to breathe rather than smell. So, when a snake is sticking its tongue out, it’s using the particles in the air to bring back to the Jacobson’s organ. This organ is above the palate of the snake and registers the molecules in the snake’s brain as a scent.

The forked tongue is not just to look cool, either. This part of a snake’s anatomy is important for their survival. Each point can intake a molecule that is then brought up to the Jacobson’s organ for analysis. A stronger scent can be determined from one of the points on their tongue, indicating a three-dimensional way of smelling. This is useful in prey location as well as finding mates.

Snakes are not the only animals with these organs. Cats also have these organs, and you can tell they’re smelling something new or strange when they sniff something and then stand with their mouth slightly parted. That’s the look of your cat analyzing a new scent in their environment.

The photo featured at the top of this post is © bugphai/iStock via Getty Images

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About the Author

Sofia is a lover of all things nature, and has completed a B.S. in Botany at the University of Florida (Go Gators!). Professionally, interests include everything plant and animal related, with a penchant for writing and bringing science topics to a wider audience. On the off-occasion she is not writing or playing with her cats or crested gecko, she can be found outside pointing out native and invasive plants while playing Pokemon Go.

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