Rattlesnakes: Hunting and Catching Prey

Summary: Rattlesnakes are excellent hunters, but how do they do it? Join Kiersten as she explains how rattlesnakes hunt and catch their prey.

 

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

“Pit Viper Can Detect Prey Via Heat” by American Museum of Natural History, https://www.amnh.org/explore/news-blogs/news-posts/pit-vipers-can-detect-prey-via-heat

“Snakes’ Flexible, Heat-Sensing Organs Explained” by Harini Barath, Scientific American, February 1, 2010, https://www.scientificamerican.com/article/snakes-flexible-heat-sensing-organs-explained

Music written and performed by Katherine Camp

Transcript 

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

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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 the seventh thing I like about this misunderstood animal is how they hunt and eat their food. We have covered some of this in the fangs and venom episode. In this episode we’ll take a look at how they find their food and catch their food.

Let’s start off with how rattlesnakes hunt. They are classified as ambush hunters, which means they lay in wait until the right prey item comes to them. I love this strategy. Maximum reward with minimum effort! 

When you are an ambush predator you need to hide well so you can catch your prey by surprise. Rattlesnakes do this by sitting very still under low foliage, fallen logs, and dark crevices. The patterns on their skin, besides making them look so pretty, is camouflage to help them blend into the background. The light and dark patterning helps break up their shape so that prey items are unaware of what is waiting in the shadows.

The second adaptation that rattlesnakes use to catch their prey is their tongue. We’ve already talked about this in the anatomy episode, but we’ll recap quickly. Snakes have forked tongues that collect scent particles when flicked into the air. Those scent particles cling to the tongue and are deposited in the Jacobson’s organ when the snakes bring the tongue back into their mouth. This organ decodes the particles and tells the snake what is in their environment. It helps them decide which direction to go when moving around their territory.

Rattlesnakes have another very cool adaptation that allows them to essentially see thermally. Yes rattlesnakes can see heat signatures. That’s amazing!

Rattlesnakes are in a group of snakes called pit vipers. This name comes from the fact that they have pits in their faces. Now, they didn’t have bad acne. These pits are by design. The heat sensing organs called ‘pits’ are located  between their eyes and nostrils. How do they work? Is it like looking through a thermal camera?

According to the American Museum of Natural  History, there is a thin membrane that connects the thermal receptor to the brain at the optic nerve. This allows rattlesnakes to see the infrared signature created by heat. They have two of these front-facing organs and this helps them triangulate the direction and distance of warm-blooded prey, even in total darkness! No night vision googles needed!

Rattlesnakes can use these heat sensitive receptors to detect infrared for up to three feet. That’s not a terribly far distance, so they use their thermal pits to help pin point where the prey is after they’ve used their sense of smell to find them. 

In 2010, a scientific study discovered the molecular process behind snakes’ night vision. They examined the nerve receptors in the pit organs of a rattlesnake. What they found was truly fascinating! Rattlesnake thermal pits produce a protein that, in other species of animals, including humans, detects chemical irritants. In rattlesnakes these “wasabi receptors”, as they are called, evolved to detect heat instead of irritants. 

Now we still don’t know exactly how snakes turn the information they receive from their thermal pts into infrared images. The membrane transfers the information to the brain, but how is it translated into a thermal image? A theoretical model proposed by University of Houston and Rutgers University researchers suggests an answer. They based some of their model on natural occurring pyroelectric materials. In nature these materials are rare but can be found in hard crystals. These types of crystals are not found in snakes. But what the paper proposes is that some soft cells can act as weak pyroelectric under certain circumstances. 

Quoting from Scientific American, “Sharma and his team developed a mathematical model to show how static charges would move in a material that is deformable and responsive to heat.” End quote. A soft material such as the membrane in the Rattlesnake’s brain. The theoretical tests that they ran showed that when a membrane thickens in reaction to increased heat, the charge on its cells should shift slightly which can result in a voltage charge that can be detected by the nerve cells. This may be how rattlesnakes use their thermal pits to see prey in the dark.

Real world research needs to be performed to prove that this is how it works, but it certainly is an intriguing idea .

Now that we know how rattlesnakes find their prey let’s look at how they catch their prey. As I said before, most of the time rattlesnakes are ambush predators. They employ a sit and wait approach to finding food. Once an appropriate item comes along and has been pinpointed, they will prepare themselves to strike. 

When waiting for prey to appear, rattlesnakes will rest with their head laterally coiled on another curve of their body. The neck will look like an S-shape and is often resting on the rest of its body that is coiled in a circular shape. This gives them the perfect amount of leverage to strike at prey. When striking prey, the snake thrusts downward with a kinking and twist in the neck. This applies greater pressure to embed the fangs deep enough so that the injected venom will do its job. Once this is done, the rattlesnake let’s go. This is all accomplished in a mater of seconds. 

The venom will act on the prey item right away and the animal typically doesn’t make it too far from the rattlesnake. If it is able to wander far enough away that the snake can no longer easily see it, they can follow the distinctive scent of their own venom to find it again. 

As discussed in the Fangs and Venom episode, the venom doesn’t only dispatch the prey item, it also begins the digestion process.  

So what do rattlesnakes eat? Excellent question listeners! I love it when you think ahead. All snakes are carnivores, which mean the eat meat. There are no snakes out their chowing down on grass or shrubby plants. They can get some veggies if they other animal they eat is a herbivore, but that’s it. 

When thinking about what snakes eat the first animal that comes to mind is mice. This is often a staple of any snakes diet but rattlesnakes do eat other types of animals. Small mammals, birds and the young of large mammals are the most frequent prey items but insects, arthropods, lizards, other snakes, frogs, toads, salamanders, and bird eggs can also be consumed. Occasionally they might be cannibalistic, eating neonate rattlesnakes. 

Young pygmy rattlesnakes eat mostly small small frogs and lizards, but adult pygmy rattlesnakes prefer voles, shrews, and deer mice. This is a trend that can be seen in many species of rattlesnakes. The young will eat smaller amphibians and reptiles but when they are adults they switch to small mammals. 

Massasaugas frequently eat small mammals and birds but will consume frogs, crayfish, fish, and lizards. I’d like to see these snakes catch a fish! The indigenous rattlesnake of Coronado Island is forced to be diurnal due to cool weather conditions eats mostly lizards because the rodents that live their are nocturnal. One of the most interesting prey items is eaten by the banded rock rattlesnake and ridgenose rattlesnakes. They eat large centipedes in genus Scolopendra.

This is risky business because these centipedes are large, have a rigid exoskeleton, and have huge pincer-like fangs with which to inject their own venom. It seems that the rattlesnake strikes near the centipede’s head, embeds their fangs between the segments, and holds on until the centipede stops moving. All I have to say to that is, Wow!

That’s it for this amazing episode. Hunting and catching prey is my seventh favorite thing about rattlesnakes.

 

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Join me next week for another episode about rattlesnakes.  

 

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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.