12 Remarkable Facts About Rattlesnakes

Because they are adaptable enough to live in desert sand dunes, wet swamplands, and green meadows, rattlesnakes can be found in a diverse range of habitats throughout the United States, Mexico, and South America. There are over 30 recognized species of rattlesnakes known today, two of which are considered endangered due to habitat loss and hunting.

One of the most misunderstood members of the animal kingdom, rattlesnakes actually play an incredibly important role in nature by controlling small mammal populations as predators and providing food to larger animals as prey. Hence, these cold-blooded reptiles deserve to be seen as important parts of a balanced ecosystem. Here are 12 things you may not know about rattlesnakes.

1. Rattlesnake Rattles Are Made From Keratin

Rattlesnakes are well known for the namesake “rattles” found at the end of their tales. The rattle is made up of various interlocking rings of keratin, the same material that human hair, skin, and nails are made of. When the snake holds up and vibrates the end of its tail, the keratin segments knock against each other and produce a unique hissing sound to ward off potential predators.

2. They Add a Rattle Segment Each Time They Shed

Once rattlesnakes grow out of their old skin and go through the molting process, their bodies naturally add an extra segment to their rattles each time. However, that doesn’t mean you can necessarily tell a rattler’s age by its tail length since it is common for segments of the rattle to break off as they age.

3. There Are More Species in Arizona Than Anywhere Else

Scientists recognize between 32 and 45 different species of rattlesnake, and many of them live in the state of Arizona. This includes the western diamond-backed rattlesnake, which is the largest rattlesnake in the West, as well as the sidewinder rattlesnake, known for its horns and side-winding movements. According to the Arizona Game and Fish Department, four species are provided special protection in Arizona: the rock rattlesnake; the ridge-nosed rattlesnake; the twin-spotted rattlesnake; and the massasauga rattlesnake.

4. They “Hear” by Sensing Vibrations

Like other snakes, rattlesnakes have an inner ear structure without an eardrum, meaning they have no way of detecting airborne sounds. While some reptiles, such as certain types of lizards, have developed tympanic membranes, the inner ear of a snake is connected directly to their jaw. Instead, snakes have to rely on sensing vibrations through their jawbone. Biologists still debate about whether snakes detect sound through pressure or mechanical vibrations through the body, however.

5. Deadly Rattlesnake Bites Are Rare

Many of us are taught to fear rattlesnakes — after all, they hiss, rattle, and, if provoked further, bite. The good news is they never seek humans out. Most people who are bitten have accidentally stumbled across a rattlesnake or attempted to handle one. And according to the Arizona Poison and Drug Information center, less than 1% of rattlesnake bites result in death.

Yet, this doesn’t mean they’re not extremely dangerous if not treated in a timely manner. All rattlesnake bites should be followed by an immediate trip to the hospital. If you hear that rattle, don’t stick around to see what comes next; the rattlesnake can strike at a speed of five-tenths of a second.

6. Their Fangs Have Hinges

Rattlesnakes are solenoglyphous snakes that belong to the viper family, which explains their especially big fangs. These types of fangs are hollow and sharp, similar to a hypodermic needle, and can inject venom. They are also hinged and lie flat against the snake's upper jaw while the mouth is closed, only to spring forward perpendicularly when the snake goes in to strike. Different snakes produce different venoms, and can even vary between snakes of the same species (such as the Mojave rattlesnake, whose venom composition can either be highly neurotoxic or highly hemorrhagic.)

7. Rattlesnake Eyes Have Vertical Pupils

Unlike grass snakes, rattlesnakes have vertical pupils in their eyes, similar to cats' eyes. Studies have shown that these slit pupils help rattlesnakes ambush their prey because it aids in depth perception. Research from 2015 found that species with vertically elongated pupils, like rattlesnakes, were more likely to be ambush predators that hunt by both day and night.

8. Females Have Live Births

Rattlesnakes are ovoviviparous, meaning they don’t lay eggs. Rather, female rattlesnakes carry and incubate their eggs inside of their bodies for around 90 days before giving birth to live young. When a baby rattlesnake is born, it comes out fully developed and wrapped inside of a membrane that it must puncture before taking its first breath of air. Breeding season for most species occurs in the springtime, and a female only reproduces every two years.

9. Their Facial Pits Sense Heat

Despite having no limbs, rattlesnakes are excellent predators. This is partly due to the heat sensitive pits on each side of their heads that make smaller animals visible to rattlesnakes even in complete darkness. The pits help detect heat, transmitting nerves to the same area of the snake’s brain that receives optic nerve impulses so it can “see” the heated image of its prey. An animal only needs to be slightly warmer than its surroundings in order for a rattlesnake to detect it successfully and strike accurately. Like all snakes, rattlesnakes have a Jacobson’s organ (also called a vomeronasal organ) on the roof of their mouths to detect, taste, and smell substances in the air.

10. They Only Eat Every Two Weeks

Rattlesnakes only eat when they’re hungry, so an adult usually goes about two weeks between meals on average. The exact amount of time depends on how big their last meal was. Rattlesnakes typically hunt mice, rats, squirrels, and rabbits, but they will also eat birds if they can catch them. A younger rattlesnake tends to eat more often, up to once a week. 

11. Baby Rattlesnakes Are Still Dangerous

Studies show that, contrary to popular belief, larger rattlesnakes inject more venom than smaller ones. As a snake grows, the quantity of venom stored in its venom glands increases, so it can release more when it strikes. Since several factors can affect bite severity, including a victim's age and body size, provocation toward the snake, site of bite, and even the victim's clothing, the propagation of certain snakebite myths leads to dangerous misinformation. Despite their small size, baby rattlesnakes still have enough venom to inflict serious damage, so it's important to treat any rattlesnake bite as a medical emergency.

12. Three Species Are Facing Threats

While most species of rattlesnakes are not threatened, there are three distinct species of concern, according to the IUCN Red List of Threatened Species. Endemic to Isla Santa Catalina, the Santa Catalina rattlesnake is considered critically endangered, while the Tancitaran dusky rattlesnake is classified as endangered due to its limited range in Mexico. Similarly, the long-tailed rattlesnake is listed as “vulnerable” since it is so rare, and only a few specimens in western Mexico have been identified over the years.