Almost everybody’s heard of the terms ‘cold-blooded’ and ‘warm-blooded.’ And we all know common examples of each: snakes and reptiles, for example, are cold-blooded. But what most people don’t know is why some animals are cold-blooded and why others aren’t.
But what you might not know is that cold-bloodedness isn’t just a matter of having cold blood. There are a lot of different bodily processes, all of which are involved in maintaining body temperature—some of which snakes have, and some of which they don’t.
- 1 What Makes a Snake Cold-Blooded?
What Makes a Snake Cold-Blooded?
What makes a snake cold-blooded is a simple fact that they don’t produce their body heat. Their blood isn’t ‘cold,’ per se; they don’t have ice running through their veins.
Cold-Blooded Animals’ Definition
The scientific term for cold-blooded animals is ectotherms.
An ectotherm is an animal that doesn’t produce their own body heat. Instead, they rely on external sources of heat to support their bodily functions. That’s the origin of the word ‘ectotherm’ itself: ecto- is from the Greek ektos, meaning outside, while –therm refers to heat.
To heat themselves, then, snakes rely on their environment. They need to be able to access both warm and cool areas, so that they can cool down and warm up as necessary.
Cool places like holes in rock formations and under loose soil or sand help them to avoid overheating during the summer, while hot rocks that sit in the summer sun can provide them with heat in the evenings, long after the sun has set.
To get a little more scientific, there are a few different kinds of cold-blooded animals. Homeothermy is where an animal is roughly the same temperature as their environment at all times, and doesn’t necessarily seek out extra heat sources.
Animals that live in the deep sea are a good example; they are only a few degrees warmer than their surroundings, and stay at this temperature at all times. Then there’s ‘mesotherms,’ which are like warm-blooded animals, but that don’t generate quite as much warmth.
What’s the Difference Between Cold-Blooded and Warm-Blooded?
Being warm-blooded is the simplest way to keep your body at a stable temperature. No more worrying about whether the sun’s coming out today; no more worrying about a cold snap during winter. The blood carries oxygen as well as warmth to every part of the body, spreading it out evenly. This means that we can have complex bodies with useful limbs: fingers, toes, and tails.
But being warm-blooded isn’t just about the blood. Warm-blooded animals have other mechanisms by which to control their temperature.
Think of a dog: what do they do when they overheat? They start to pant. Drawing in a sharp intake of breath cools the tongue by running air over it, and the tongue, being full of blood, then spreads throughout the body. In this way, the whole body cools down.
Other methods include:
- Sweating, which cools an animal’s skin down through the evaporative process. Capillaries carry blood to the skin, and this cooled blood flows to every part of the body.
- Shivering and shaking, which warms the body up: muscle activity creates warmth, and this warmth spreads through the body through the blood.
- Cell activity creates heat. Chemical reactions in our cells release energy; it’s thought that up to eighty percent of this activity has no purpose other than to generate heat.
Most cold-blooded animals don’t share these mechanisms by which to cool or warm themselves up. They rely solely on external heat. But, curiously, some of them do; bees, for example, will agitate their flying muscles without actually flying to warm them up. Snakes, though, will only bask to increase their temperature.
Why Are Some Animals Cold-Blooded?
Many species around the world are cold-blooded. These include amphibians like frogs and toads, insects like bees, flies, and ants, and reptiles.
All of these animals, snakes included, are cold-blooded because it gives them certain advantages in the wild—just like how us being warm-blooded gives us certain advantages, too.
What Are the Advantages?
The fact that snakes are cold-blooded means that they need far less energy to survive. Mammals need to eat more food, and more frequently, than snakes so that we can maintain a high body temperature. This high temperature supports the function of our organs.
Snakes don’t need these high temperatures, so they don’t need to eat as much. That’s why they can go so long without food. Besides that, there are many other advantages to being cold-blooded:
- Bacteria and viruses thrive inside warm bodies. As such, a cold-blooded animal is less likely to catch any. And if they do, the resultant infection or illness is less likely to be serious.
- Snakes’ brains needn’t be as complex as those of mammals, because they don’t need a variety of biological processes to regulate their temperature. From our perspective, an animal not being as intelligent as it could be would seem like a disadvantage; but less complex brains use less energy, which is a good thing for an animal in the wild.
- It means that there can be more of them in a certain habitat than there otherwise would be. That’s because endothermic (warm-blooded) animals have to eat higher amounts of other food, whether that’s vegetation or other creatures. Because cold-blooded animals eat less, there’s more food to go around, meaning larger populations can be sustained.
- Many snakes save energy by practicing ambush hunting. This is where the snake sits and waits for prey to wander by, often from a secluded or camouflaged position, before striking. Some snakes sit on tree branches waiting for birds, like green tree snakes; others disguise themselves under loose sand, like the sidewinder rattlesnake. This method of hunting preserves plenty of energy, and also doubles as a way to hide from predators.
Ultimately, all animals have evolved to fit an ecological niche. While we’ve done that by being warm-blooded, snakes have done so by being cold blooded. For snakes, the advantages above are more than enough for them to get by. They wouldn’t necessarily be any better off if they ‘switched,’ although there are disadvantages to being cold-blooded too.
What Are the Disadvantages?
Cold-blooded animals have to face many different problems on a daily basis. These are:
- During the winter, snakes can’t keep themselves warm. As such, they have to become far less active than they otherwise would be. This prevents them from hunting, mating, or doing anything else useful. This is known as brumation, which is similar to hibernation.
- During warmer months, snakes have to spend several hours a day basking somewhere warm. This takes up much of their time that they could spend doing something useful.
- Because they rely on the sun’s heat, cold-blooded snakes are more sluggish in the morning and the late evening. They quite literally have to warm up their body before they can maintain higher levels of activity. Unfortunately, this makes them easier targets for predators.
- Animals rely on body heat to digest, and snakes are no exception. Much of our digestion relies on bacteria. As such, snakes have to bask somewhere warm to digest. This is another reason they can’t digest in the winter. A paper in the Journal of Experimental Biology highlights how rattlesnakes adjust their behavior to stay warmer when they need to digest.
- They’re more challenging to care for as pets. You have to provide them with sources of warmth as well as a cooler area. If you don’t, they could die.
The fact that snakes rely on their environment to keep warm also means that they’re particularly susceptible to climate change. When the temperature of a particular habitat changes drastically, this affects the ability of the snake to regulate the heat of their own body.
Remember, temperature regulation cuts both ways: snakes also have to find ways to keep cool during the summer. In places that are already quite hot or quite cold, they’re at risk if the temperatures get any higher or lower.
Are There Any Warm-Blooded Snakes?
Snakes are the most widespread group of species on earth. As such, they’ve had to adapt to climates from the far north and south to the equator. In these places, they’ve adapted to fit in: changing their color and behavior. Sea snakes have even developed the ability to take in some of their oxygen through their skin, so that they can breathe underwater. All of this is to ask: are there any snakes that have become warm-blooded to fit into their environment?
No, there are no known warm-blooded snakes. Snakes are most common in warm places, like those around the equator. They are far less common, with their most northerly reach being around southern Canada. Specifically, they can’t move any further north than areas where the ground freezes in winter. Snakes can burrow, and will during the winter, to avoid the worst of the cold temperature.
But in areas where the ground freezes, snakes can’t do this. During the winter, they would still try to burrow and hide away, but the frozen ground would kill them before too long. This is like a hard border for an animal that can’t generate their own heat. If there were any warm-blooded snakes, this is where we would find them, but so far none have been discovered.
How to Care for a Snake
Because a pet snake can’t regulate their temperature, you have to do it for them. If you don’t, your pet will become ill, could be stressed, and may even die. There are many means to help them maintain adequate body temperature, including:
- Regular misting. Most snakes need high levels of humidity anyway, so spraying them regularly is a part of basic care. This also helps them to cool down if it’s too hot.
- Heat mats sit underneath a snake’s enclosure. These provide a continuous source of heat.
- Heat bulbs. These are like light bulbs, but which only give off heat. You can also use light bulbs, but they aren’t as efficient.
What you have to do is keep one side of the enclosure warm—a basking spot. The other side of the enclosure should have a steady temperature with no belly heat. This allows the snake to regulate their temperature by heading to one side of the enclosure or the other.
They can choose to cool down or warm up, whenever they like. This is a better alternative to keeping the enclosure at one temperature, which could cause the snake to overheat or become too cool.