Rattlesnakes: Rattle

Ten Things I Like About... Podcast

Summary: Rattlesnakes are the only types pf snakes with a rattle, hence the name. But how much do you know about the rattle? Join Kiersten as she tells you everything you ever wanted to know about a rattlesnake’s rattle.

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean

Show Notes:

Rattlesnake: Portrait of a Predator by Manny Russo

“How Do Rattlesnakes Rattle?” By Cameron Duke, Live Science, August 12, 2023. https://www.livescience.com

Music written and performed by Katherine Camp

Transcript

(Piano music plays)

Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

(Piano music stops)

Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating.

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

This episode continues rattlesnakes and today we’re going to learn about their namesake. The rattle on a rattlesnake is the eighth thing I like about this charming snake.

In the Anatomy episode, I touched on the rattle but this episode will be a deeper dive into this unusual physical attribute.

Rattlesnakes are not born with a rattle but they are born with the beginning of a rattle. They are born with what’s called a prebutton. The prebutton is a skin cap on the tip of the neonates tail. This is different from any other young snake’s tail. Only rattlesnakes have a prebutton. It is essentially a terminal scale like other snakes’ have on the ends of their tails, but it’s larger in size. Most snakes, other than rattlesnakes, have a tapered cone-shaped scale at the end of the tail, where as the rattlesnakes’ scale is wider and thicker.

When the neonate rattlesnake molts for the first time, a few days to a week after birth, the prebutton they are born with sheds. After this molt another button is revealed that will be the beginning of the rattle that they will have for the rest of their lives. With each following molt a segment will be added to the rattle, creating a rattle chain.

So, what is this rattle made of? It’s made of something very common in the natural world. You, listeners, have some of it on you right now in the form of hair and fingernails. That’s right, the rattle is made of keratin. Those of you who listened to my pangolin series should remember that keratin is the fibrous protein that is the main component of hair, feathers, hooves, claws, and horns. Just one more thing that links us all together.

Let’s get back to the rattle chain. The links are hollow and each link interconnects with the one below it. A link is created each time the snake sheds. To grow larger snakes must shed their skin. Unlike us, their skin is not flexible enough to grow as they grow. So they must shed their skin to get bigger. Each time a rattlesnake sheds, the old skin leaves a piece behind on the tail creating a new link.

When the old piece is pushed out by the shedding process, a new button develops beneath the new rattle link. This will be pushed out at the next shed. This brings us to a myth about rattlesnakes and aging. Many people believe that you can determine the age of a rattlesnake by the number of links on the rattle. If snakes only shed once a year, that would be true. But as I just explained, snakes shed when it’s time for them to grow. That can happen multiple times a year. Growth rates all depend on the amount of food that a snake consumes. When resources are abundant, a snake can grow quickly; when resources are scarce, a snake may grow slowly.

Another reason judging a rattlesnake’s age by the rattle is problematic is that they aren’t very sturdy. Rattles are hollow and made of keratin, so they aren’t rugged enough to survive the rough and tumble life of a rattlesnake. When the rattle chain gets too long links will break off. In the wild, having a rattle with ten links is uncommon. Most rattlesnakes will be able to hold onto five or six links at a time.

It’s not like they make a concerted effort to shortened their rattle, but slithering around on the ground can be hard on a hollow piece of keratin. When the rattlesnake travels they do hold the tail up keeping the rattle almost perpendicular to the ground. But avoiding predators or avoiding getting stepped on can lead you into some precarious situations that can cause the ends of the rattle to break off.

Rattlesnakes in captivity are another story. They tend not to travel too far and their rattles are never exposed to rough terrain. Some captive rattlesnakes have been recorded with rattle chains containing twenty or more links. That’s a pretty long rattle!

Now there is another reason why the rattle cannot be too long. If it’s too long it doesn’t do it’s job properly. The point of a rattle is to make a noise. If there are too many links, the weight of the links prevents the rattlesnake from lifting it up to shake it. No shaking, no noise.

So where does the noise come from? Is there something inside the rattle that creates the noise, like a maraca? No. The links are hollow and interconnected, so the noise is produced by the sides of the links knocking together. Some rattlesnakes produce a noise that can be heard many yards away.

In 2021, researchers discovered that rattlesnakes are capable of creating an auditory illusion with their rattle. This is good stuff, listeners! They discovered that when a rattlesnake feels threatened it begins rattling it tail at a low frequency. If the predator keeps approaching, the snake’s rattling frequency suddenly increases by 20 or 30 hertz. This creates the illusion that the snake is much closer than it actually is in reality. That is wicked cool!!

The actual sound of the rattle will depend on the species. Larger rattlesnakes such as eastern diamondbacks will have a deeper sound, where as smaller species like the pygmy rattlesnake will have a higher pitched noise. The noise created by a rattlesnake’s rattle has been described as a buzz, a whirr, a clatter, a hiss. It has been compared to the sound seeds in a dry seed pod make, the sizzle of bacon, the buzz of an insect, the grinding of a knife blade, or even the sound of running water. I used to live in the deserts of Arizona. I heard my fair share of rattlesnake warnings, and I wouldn’t describe it in any of these ways. It’s a distinctive sound they you instinctually know when you hear it.

To make sure that a rattlesnake can always move their rattle when needed, they have a specialized muscle called a shaker muscle in their tail. This particular muscle contracts at a rapid and consistent rate. It is also slow to fatigue, so the snake can shake its rattle for a long time, if needed. The muscle is supplied with large amounts of oxygen through a series of blood vessels.

The last question we have to answer is why do rattlesnakes have rattles? Scientists still aren’t entirely sure, but their best educated guess is that it is a predator warning. To keep themselves from getting stepped on or eaten, rattlesnakes produce a noise to warn off whoever is threatening them.

A study performed in 2016 by an undergraduate at the University of North Carolina at Chapel Hill, investigated the evolution of the rattlesnake’s rattle. The ancestors of modern day rattlesnakes did not have rattles, but it’s likely that they shook their tails despite the lack of a rattle. This study looked at the tail-shaking behavior of 56 snake species. Rattlesnakes were the only snakes included in the study that had rattles, but most of the snakes in the study rapidly flicked their tails when threatened by a predator. Further more, the snake species more closely related to rattlesnakes flicked their tails faster and more frequently than species more distantly related to rattlesnakes. This leads scientists to believe that when rattlesnakes developed their rattles, they already knew how to use them.

Thanks for listening to me rattle on about rattlesnake’s rattles because it’s my eighth favorite thing about this amazing animal.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change.

Join me next week for another episode about rattlesnakes.

(Piano Music plays)

This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.