What is a Reptile?
Reptiles are a cool group of critters – and not just because they are cold-blooded! They are part of a bigger category of animals called vertebrates, which means they all have a backbone. There are seven different groups, or classes, of vertebrates on Earth. These include amphibians, birds, mammals, reptiles, and three kinds of fish.
Reptiles are not the easiest group to define. There are many types of reptiles with diverse characteristics and behaviors. From legless snakes to shelled turtles and armored crocodiles, the reptile group has some incredible creatures. Unlike other classes of vertebrates, scientists now know that the group we call reptiles is not an isolated evolutionary lineage. This means that despite their many similarities, some members of the reptile group are not quite as closely related as people once thought they were. Additionally, we now know that birds descended from a reptile ancestor – so in a way, birds and reptiles are relatives!
Don’t fret if all this seems confusing. Luckily, all reptiles share a few unique traits that can help us distinguish them from other animals. In this post, you’ll read about four traits that all reptiles have!
Before We Dive In: A Quick Resource for Teachers 🍎
If you’re teaching reptiles, visuals and hands-on activities are key to keeping your students engaged and excited. My Complete Reptiles Unit is packed with colorful illustrations and fun lessons to bring this topic to life. Plus, every purchase helps support this blog! ❤️
Skeletal Features
Like all vertebrates, reptiles must have a backbone. A backbone is actually made of many individual smaller bones called vertebrae all stacked up in a flexible column. Reptiles’ spines help us tell them apart from invertebrate (backbone-less) creatures like insects and mollusks.
Apart from their spines, reptiles’ skeletons don’t share much in common with each other. While all reptiles have jaws, some have a single jawbone, while others have flexible jaws made of multiple bones. Not all reptiles even have the same number of limbs. While turtles, crocodiles, and most lizards have four limbs, snakes have no limbs at all.
Breathe Air With Lung(s)
All reptiles breathe. However, not all reptiles have two lungs. Interestingly, many snakes only have one working lung. Even the reptiles that live in water have lungs. Despite their excellent swimming skills, sea turtles, water snakes, and marine iguanas all come to the surface to breathe air.
However, some of these animals can all hold their breath for much longer than you or me. While a human might be able to hold their breath for about a minute, a sea turtle might hold its breath for as long as 2 hours when resting. However, if they cannot get to the surface to breathe for some reason, sea turtles (like any reptile) can drown. They do not have gills like fish and sharks.
Scales or Scutes
A reptile has scales or scutes covering its body. You may already be familiar with scales. Scales are overlapping, shingle-like surfaces that make up a snake or lizard’s skin. Scales are part of the epidermis or outer skin. They are made of keratin, like your fingernails. A reptile will shed and regrow its scaly skin multiple times throughout its life. Reptiles are not the only animals with scales. Fish have scales too.
You might be wondering: what is a scute? A scute is a thick, armored plate found in turtle shells and the skin of crocodiles and alligators. Reptiles are not the only animals with scutes. Scutes also make up the rough-textured surface of birds’ legs.
While scales and scutes are not unique to reptiles, they are helpful traits that can help us tell the difference between a reptile and an amphibian. Amphibians never have scales or scutes – instead, they have distinct moist, smooth skin.
Cold-blooded
Ever wonder why you see snakes and lizards sitting out in the sun? Reptiles are cold-blooded or ectothermic animals, which means their body temperature depends on the temperature of the air or water around them. They must rely on external (outside of themselves) heat sources to stay warm rather than making their own body heat.
When reptiles need to warm up, they sun themselves. If they get too hot, they go underground, into cool water, or find shade. Because they rely on external heat sources, their temperature varies a lot. Reptiles, amphibians, and most fish are cold-blooded animals.
Teaching Reptiles in Your Classroom
There’s no need to scramble to put together the perfect lesson for teaching reptiles – I’ve already created it for you! This set includes all the printable materials you need for studying reptile traits and more.
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References and Further Reading
- Greater Cleveland Aquarium (2019). EXPLORING SIMILARITIES, CELEBRATING DIFFERENCES: AMPHIBIANS AND REPTILES. Available: https://www.greaterclevelandaquarium.com/exploring-similarities-celebrating-differences-amphibians-and-reptiles/
- NOAA Fisheries (2022). Fun Facts About Terrific Sea Turtles. Available: https://www.fisheries.noaa.gov/national/outreach-and-education/fun-facts-about-terrific-sea-turtles
- Sanker, E.A. (2024). What is a scute? All Things Nature. Available: https://www.allthingsnature.org/what-is-a-scute.htm
- Schick, M. (2015). Amphibian or Reptile? Here’s the Difference. Shedd Aquarium. Available: https://www.sheddaquarium.org/stories/amphibian-or-reptile-here-s-the-difference
- Uetz, P. (1996). General Information (and “FAQ”). The Reptile Database. Available: http://www.reptile-database.org/db-info/introduction.html