Are Turtles Reptiles? A Dive into the World of Turtles (2024)

The lifestyles and behaviors of different turtle species may raise the question: are turtles reptiles?

Turtles belong to the class Reptilia, which means turtles are reptiles. There are several characteristics that set reptiles apart from other types of animals, such as amphibians, birds, and mammals.

Most reptiles are cold-blooded, or ectothermic. Many also lay eggs and breathe air through their lungs.

We’re going to break down how turtles are classified as reptiles and the evolution and characteristics of different turtle groups.

What Are Turtles?

Turtles are reptiles with shells attached to their ribs. Some turtle species live exclusively in marine habitats, while others live in freshwater or strictly on land.

The most common type of turtle found in North America is called a terrapin. These turtles live in freshwater habitats.

Other types of turtles include sea turtles and tortoises. Sea turtles are marine-dwelling creatures. Tortoises are turtles that live exclusively on land.

Like most reptiles, turtles are cold-blooded. This means that their body temperature changes with their surrounding environment.

You may have seen turtles basking in the sun on logs or riverbanks. Turtles like to bask in the sun to warm up their bodies since they can’t regulate it on their own. When they’re too hot, turtles will find a shady spot or burrow underground to keep cool.

Reptiles are known for their scaly skin. Some reptiles possess scales on their “skin,” but turtle scales are located on the shell.

The scales on turtle shells are referred to as scutes. When turtles grow, the scutes peel off, and a new set of scutes takes their place.

Most turtles have a hard shell made of keratin. The turtle family Trionychidae consists of soft-shelled turtles, which possess leathery shells made of cartilage rather than keratin.

Evolution: How Old Are Turtles?

In order to understand how turtles are reptiles, it’s important to look at how they’ve evolved. There is still a huge debate over where turtles came from.

It’s known that turtles appeared on Earth during the Triassic Period about 230 million years ago, but what they evolved from is largely up for debate.

Scientists continue to study the evolution of turtles to identify potential ancient ancestors. Scientists and researchers have concentrated on the development of the shell to better understand the lineage of turtles.

Reptiles are known to have evolved from Amniotes, which is a clade of terrestrial vertebrates that also includes birds and mammals.

A split occurred during the Carboniferous Period about 340 million years ago. Two major groups were created, which include Synapsids and Sauropsids. Sauropsids include reptiles and birds.

Sauropsids are further separated into two main groups, which include anapsids and diapsids.

This separation depends on the presence or absence of openings in the skull near the eye sockets called temporal fenestrae. Modern-day diapsids include birds, crocodilians, lizards, and snakes.

Despite turtles having a similar skull structure to anapsids, new studies suggest that they may be tied to the diapsid group based on molecular evidence.

It’s possible that the ancestors of modern turtles may have possessed temporal fenestrae but slowly lost them over time.

A 2008 fossil discovery in the Nanpanjian Trough Basin in China has contributed to new evidence that changes paleontologists’ initial theories on the lineage of turtles.

The fossil, scientifically described as Odontochelys semitestacea, is about 220 million years old.

The discovery has led some researchers to believe that turtles may have evolved in a marine habitat.

The find indicates that Testudines developed the top part of the shell, called the plastron, before the bottom, or carapace. This hypothesis contradicts previous theories of the shell fusing together from bony deposits.

Other paleontologists argue that the lack of carapace in the fossil specimen suggests it could’ve been an adaptation to a marine environment.

Another discovery of a fossilized juvenile prehistoric lizard-like species, Eunotosaurus africanus, suggests turtles are more closely related to birds and crocodiles than snakes and lizards.

The fossil is 260 million years old and could be a key link in understanding the evolution of turtles.

Since the specimen fossilized as a juvenile, researchers found that it had temporal fenestrae.

According to Yale University assistant professor Bhart-Anjan Bhullar, this suggests that the temporal fenestrae of the specimen eventually closed later in life.

There is still more research needed to identify common ancestors between prehistoric reptiles and modern-day turtles and fully understand their evolutionary processes.

The key to these studies is identifying when the common ancestors of these reptiles developed shells and how.

Classification of Turtles

The term turtle is often used to describe all turtle species.

However, there are three main groups that separate different turtle species. These groups include turtles, terrapins, and tortoises. Turtle species in each of these groups have different adaptations, lifestyles, and appearances.

All modern turtles belong to the order Testudines. The order is further separated into two main groups, which include Pleurodira and Cryptodira.

The classification of turtles in these two taxonomic groups depends on how the head retracts into the shell.

Hidden-necked Turtles

Turtles in the suborder Cryptodira are called hidden-necked turtles. These turtles are capable of retracting their necks straight back into their shells. North American box turtles are hidden-necked turtles.

The separation between hidden-necked turtles and side-necked turtles is believed to have occurred during the late Triassic period, about 210 million years ago.

Side-necked Turtles

The suborder Pleurodira refers to side-necked turtles. These turtles aren’t capable of retracting their necks vertically into their shells. Side-necked turtles turn their heads to the side to tuck their heads inside the shell.

Side-necked turtles usually have longer necks compared to hidden-necked turtles.

The African side-necked turtle is an example of a turtle species in the suborder Pleurodira. The species is also called the African helmeted turtle.

Types of Turtles

Types of turtles are separated into three main groups, which include turtles, terrapins, and tortoises.

The term turtle is often used to refer to any type of Testudines, but not all turtles are the same. The three main groups of turtles help differentiate the characteristics, lifestyles, habitats, and appearances that different Testudines have.

Turtles

Although the term turtle can be used to describe all turtle species, it’s sometimes used to refer to sea or marine turtles. These turtles live almost exclusively in marine habitats.

There are seven types of living sea turtles. Sea turtles only come to land to lay eggs. Females typically return to the same nesting site each year to lay eggs in coastal areas. Males usually never come on land.

After incubating in the warm sand for about two months, baby sea turtle hatchlings emerge and make their way to the ocean.

For males, this is usually the last time they’ll come ashore. Once females reach sexual maturity and mate, they will return to their natal nesting site to lay eggs.

Sea turtles have special shells and fins to make them more hydrodynamic. Unlike many turtles, sea turtles aren’t capable of retracting their heads or limbs into their shells.

The leatherback sea turtle is the largest living sea turtle. It can weigh anywhere between 550 and 2,000 pounds (249 and 907 kg) and reach up to 6 feet (1.8 m) in length!

Almost all sea turtle species face the risk of extinction. The Kemp’s ridley sea turtle is the most endangered sea turtle species.

Almost all sea turtle species are classified as vulnerable, endangered, or critically endangered. The flatback sea turtle is the only species that scientists don’t have enough data on to determine its conservation status.

Terrapins

Terrapins are freshwater turtles that spend most of their time in or around freshwater habitats. They can also be found in brackish-water habitats.

Terrapins have flatter shells compared to the dome-like shape of tortoise shells. They also have webbed feet, which come in handy for swimming in water.

Some examples of terrapins include:

• Red-eared slider (Trachemys scripta elegans)
• Yellow-bellied slider (Trachemys scripta scripta)
• Painted terrapin (Batagur borneoensis)
• Mexican spotted terrapin (Rhinoclemmys rubida)

If you spot a turtle with a flatter shell near or swimming in freshwater, it’s likely a terrapin. These turtles usually don’t stray too far from their freshwater habitat.

Although most terrapins are easily recognizable due to their flattened shells, some terrapins make identification a little difficult.

For example, North American box turtles are considered terrapins despite their rounded shell shape.

Box turtles can be found farther away from freshwater sites. They’re common backyard visitors in the States.

On a hot summer day, box turtles may be spotted hiding out under vegetation where moist soil keeps them cool. They’re mostly terrestrial, but they do live near permanent and temporary bodies of freshwater.

Tortoises

Tortoises are land-dwelling turtles. They live exclusively on land. Tortoises don’t have the same characteristics as terrapins to venture into water.

Tortoises may live near permanent or temporary bodies of water because they need drinking water. However, tortoises are strictly terrestrial. They have unwebbed, stumpy feet meant for walking on land.

The front limbs of tortoises are stronger and longer than the back limbs, which helps them dig burrows.

Unlike turtles and terrapins, which are omnivores, most tortoises are strictly herbivores. They mainly feed on grasses and low-hanging vegetation. Tortoises that live in arid and semi-arid habitats will also eat cacti.

One of the most visible differences between turtles and tortoises is the shape of their shells. Tortoises have a dome-shaped shell, while turtle and terrapin shells are more flat.

Difference Between Turtles and Amphibians

You might be wondering: how are turtles reptiles if some species spend part of their lives on land and in water? This may lead to some confusion, as amphibians are known to live in water and on land. However, there are several differences between amphibians and reptiles.

Amphibians typically begin their life cycle in water, whereas reptiles typically begin their life cycle on land.

Most amphibians can breathe through their skin, while reptiles use their lungs to breathe. Even sea turtles need to come up to the ocean’s surface for air.

However, sea turtles have special adaptations that allow them to stay underwater for long periods of time.

Some other characteristics that distinguish turtles from amphibians include:

• Amphibians secrete mucus to keep their skin moist, but reptiles have scaly skin better suited for dry environments.
• Reptile eggs have a leathery texture, while amphibian eggs are made of a jelly-like substance.
• Amphibians are more susceptible to harm from water pollutants because of their porous skin.
• Amphibians are born with gills and develop lungs as they mature, but reptiles are born with lungs.
• There are no true amphibian species that live in marine habitats.

While amphibians and reptiles are very different, they share some common characteristics.

Amphibians and reptiles are cold-blooded, so they can’t regulate their body temperature on their own. Both groups are also vertebrates. All amphibians and reptiles possess a spine.

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Turtles in Mythology and Folklore

Turtles have long been depicted in mythology and folklore.

One of the most consistent symbols of turtles in many cultures is strength and longevity. These traits are mainly attributed to the tortoise because of its hard shell and long lifespan.

The World Turtle is depicted as a turtle supporting the world on its back. This depiction is represented in many different cultures and religions, including Hinduism, Chinese mythology, and Native American mythology. Akupara is the World Turtle in Hindu mythology.

In Nigerian folklore tales, a tortoise named Ijapa is depicted as a trickster.

Tortoises are considered sacred creatures in Chinese culture. The black tortoise is one of the four mythological creatures of the Chinese constellations, which represents north on the compass and symbolizes the water element.

You may be most familiar with the famous ancient Greek story of The Tortoise and the Hare in Aesop’s Fables. The tale starts with the hare mocking the tortoise for his slowness. The tortoise challenges the horse to a race.

In the story, the tortoise symbolizes patience and diligence. The hare symbolizes carelessness and arrogance. The story demonstrates the commonly used expression “slow and steady wins the race”.

Turtle Fun Facts

Turtles have beaks.

One of the key characteristics that defines turtles is their lack of teeth. Turtles have strong beaks that allow them to munch on various types of vegetation and other foods.

The type of beak a turtle has depends on what type of food it eats.

For example, herbivorous turtles have flat beaks designed for grinding down vegetation. Turtles that eat meat have hooked beaks that allow them to crush their prey before consuming it.

The meaning of turtle, tortoise, and terrapin can depend on where you live.

Although we’ve described the main types of Testudines, the terms tortoise, turtle, and terrapin can mean different things depending on the region.

Some places use the term turtle to refer to all species in the order Testudines. However, some regions use the term to describe sea turtles.

Turtle is commonly used in the US to refer to all Testudines species. In the United Kingdom, people often refer to sea turtles as turtles.

The hissing sound of turtles isn’t because they’re angry.

If you’ve ever picked a turtle up and it retracted in its shell, you may have noticed it making a hissing sound. While this sound may seem like an intimidation tactic, it’s not!

Turtles hiss when they retract into their shells because they’re expelling air from their bodies.

Sometimes hidden-necked turtles need to make space inside their shell by expelling air. The hissing sound you hear is the air they’re releasing to fit in their shell.

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