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The Secrets of Sidewinders

How can some snakes move quickly over sand?

By Andie Choi
From the October/November 2021 Issue

Learning Objective: Students will summarize discoveries from a scientific investigation studying how sidewinder snakes are adapted to move in sandy deserts.

Lexile: 840L; 650L
Guided Reading Level: S
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Have you ever tried running on sand? It’s hard to do because your feet sink in. Moving across sand can be a struggle for many animals. But it’s no problem for sidewinders! These species of snakes live in deserts in North America, Africa, and the Middle East. They easily move their long bodies across the slippery sand.

Have you ever tried to run on sand? It’s hard to do because your feet sink in. Moving across sand can be tough for many animals. But it’s no problem for sidewinders! They’re a species of snake. They live in deserts in North America, Africa, and the Middle East. The snakes easily move their long bodies across slippery sand.

COURTESY OF JENNIFER RIESER

JENNIFER RIESER

Jennifer Rieser wanted to better understand this movement. She’s a scientist at Emory University in Atlanta, Georgia, who studies how soft materials, such as sand and mud, change when forces are applied to them.

Rieser wondered how animals travel on Earth’s different surfaces and textures. She set out to investigate how sidewinders’ skin might help them wriggle over sand.

Jennifer Rieser wanted to learn more about this movement. She works at Emory University in Atlanta, Georgia. She’s a scientist who studies how forces affect soft substances like sand and mud. Rieser wondered how animals travel over different materials. She studied sidewinders’ skin to learn how it might help them wiggle over sand.

Making Moves

Snakes move in different ways. Mostsnakes slither forward by turning their heads left to right, bending their bodies in an “S” shape. The snakes press off hard surfaces and push themselves straight ahead.

Instead of moving forward, sidewinders move sideways. They lift sections of their body off the ground, “almost like feet,” Rieser says. The snakes can control how much of their body is touching the ground. That reduces the risk of causing the sand to shift beneath them and sliding down sandy hills.

To find out whether the sidewinders’ skin helps them move, Rieser and her colleagues examined the shed skin of three sidewinders. She then compared them with the shed skin of non-sidewinders.

Snakes move in different ways. Most snakes slither forward. They turn their heads left to right. And they bend their bodies in an “S” shape. The snakes press off hard surfaces. Then they move straight ahead.

But sidewinders don’t move forward. They move sideways. The snakes lift sections of their body off the ground, “almost like feet,” Rieser says. That helps prevent the sand from shifting beneath them. And it makes it less likely they’ll slip down sandy hills. 

Rieser studied the shed skin of three different sidewinders. She wanted to learn whether it helped them move. She compared the skins with those of other snakes. 

EMANUELE BIGGI/NPL/MINDEN PICTURES

Sidewinders move sideways, leaving horizontal S-shaped tracks in the sand.

Skin Up Close

Snakeskin is made up of folds called scales. Under a microscope, the scales on the bellies of many snakes have tiny spikes pointing toward their tails. These spikes increase friction, a rubbing force, between the snake’s belly and the ground in one direction. That friction helps the snake grip the ground and push itself forward.

Many snakes that don’t live in sandy environments would likely not move well if they were on sand. The tiny spikes on most snakes’ bellies would not help, says Rieser. The snakes might even end up buried!

Snakeskin is made up of folds called scales. Under a microscope, tiny spikes can be seen on the scales on many snakes’ bellies. The spikes point toward the snakes’ tails. They add friction, which is a rubbing force, in one direction. It happens between the snake’s belly and the ground. That friction helps the snake grip so it can push itself forward. 

Some snakes don’t live in sandy areas. They likely wouldn’t move well if they were on sand. The tiny spikes on their bellies would not help, says Rieser. The snakes might even end up buried!

TAI-DE LI/COURTESY OF JENNIFER RIESER

Microscopic textures on snake bellies help the snakes move. Sidewinders have round pits (right). Other snakes have spikes (left).

Up close, the sidewinders’ bellies look much different than those of the other snakes studied. Their skin has tiny circular pits. The pits produce equal friction in all directions. That keeps the sand from shifting and allows sidewinders to move quickly.

Rieser wants to learn more about how animals evolved to move in their natural habitats. She also hopes her research inspires new types of robots. “We could help robots move in challenging environments,” she says.

Up close, sidewinders’ bellies are different. They don’t look like those of the other snakes studied. Their skin has tiny circular pits. The pits produce equal friction in all directions. That keeps sand from shifting beneath them. It allows sidewinders to move quickly. 

Rieser wants to learn more about these animals. She wonders how they evolved, or change over time, to move the way they do? She also hopes her research inspires the creation of new types of robots. “We could help robots move in challenging environments,” she says.   

video (1)
Activities (3)
Answer Key (1)
Step-by-Step Lesson Plan

1. ENGAGE: Make hands-on observations about sand and consider what animals need to live in a sandy environment.

  • Together, list characteristics of a desert environment (e.g., sandy, low rainfall, extreme temperatures). Tell students they are going to explore traits of sand to help understand how it creates challenges that desert animals have to be adapted to.
  • Preview the Scoop, Pour, Explore hands-on activity. Emphasize safety expectations such as keeping sand near the container and away from people’s eyes. Have small groups complete the activity.
  • Discuss what students noticed and figured out about sand, such as differences between one grain of sand and the entire tub of sand. Draw representations of students’ ideas as needed.

2. EXPLORE: Watch a video about sidewinders and model snake movements.

  • Tell students they’re going to learn about a snake called a sidewinder that’s adapted to move in sandy deserts. Play the video “Sidewinding Snakes.” Then encourage students to safely use one arm to kinesthetically show the sidewinder’s motion and then the other snake’s motion.
  • Ask: How are a sidewinder’s movements different from those of most other snakes? (e.g., direction of movement, lifts its body more) Why do you think sidewinders move differently?
  • Pause and ask: How does walking move a person forward? (by exerting force against the ground) How do you think a sidewinder pushes itself forward in deep sand? Encourage students to think about their earlier observations of sand and to explain their thinking. Explain that you’re going to read about a scientist who wanted to know more about sidewinders’ unique movements.

3. EXPLAIN: Read the article and summarize scientific observations and analyses.

  • Write the words observation and analysis on the board. Discuss each word. Read the article, noting examples of observation (e.g., looking closely at a sidewinder’s shed skin) and analysis (e.g., figuring out how the surface of the skin affects motion). Then have students complete the Investigate It! skills sheet. Discuss as a class.

4. EXTEND: Evaluate how well animals could survive in different environments.

  • Show students a picture of a forest and of a desert. Beneath each picture, note the traits of each. Then ask: What do snakes need to survive? (e.g., food, water, shelter, ability to move from place to place) What might happen to a snake adapted to the forest if it was put in a desert? (e.g., the snake might struggle to move, might not be able to survive the heat)
  • Replay the “Sidewinding Snakes” video and refer to the text. Revisit what might happen to a snake adapted to the forest if it was put in a desert. Discuss how the skin structures would make it hard for the forest snake to move across sand.

5. EVALUATE: Use a low-stakes quiz to reinforce key ideas from the text.

  • Preview the Quick Quiz. Have students complete in pairs and discuss their answers as a class.

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