Turtles of North America: Classification and Evolution

Turtles of North America are divided into seven families, with the most common being the Sea Turtles and the Land Turtles.

The Sea Turtles belong to the family Cheloniidae and are further divided into five species, including the Leatherback Sea Turtle, which is the largest turtle in North America.

The Land Turtles, on the other hand, belong to the family Emydidae and are made up of 57 species, including the Snapping Turtle and the Painted Turtle.

These classifications are based on the turtles' unique characteristics, such as their shell shape and size, as well as their habitat and behavior.

A fresh viewpoint: Northern River Otter Mustelidae Family

North American turtles are incredibly diverse, with over 60 species found throughout the continent. Some of the most fascinating species include the sea turtles, snapping turtles, and box turtles.

The largest Illinois turtle is the alligator snapping turtle, which can grow up to 30 inches in length and weigh over 250 pounds. That's massive!

Aquatic turtles in the wild can live up to 70 years, while certain terrestrial species like the eastern box turtle can live for 100 years or more. That's a long time to be carrying around a shell!

Many species of turtles have temperature-dependent sex determination, meaning the sex of the embryo depends on the temperature within the nest at a critical period. This can result in all-male or all-female hatchlings.

In Illinois, turtle eggs typically take about two months to hatch, and some species like painted turtles overwinter in the nest before emerging in the spring. That's a long wait!

Here's a breakdown of the different types of turtles found in North America:

Some species of turtles are in danger, like the endangered Coahuila box turtle, which has seen its population decline by 40% in the past 40-50 years. Conservation efforts are underway to help protect these amazing creatures.

Turtles are members of the Phylum Chordata and Class Reptilia, with a unique shell that has as many as 60 bones.

Their shell is made up of two sections: a carapace covering the back and a plastron covering the belly, connected by a bony bridge.

In most species, large scales called scutes overlay the bones, but in softshell turtles, a tough leathery skin replaces the scutes.

Turtles usually have a prominent tail that varies in size with sex and species.

Here are the seven species classified within the genus Terrapene:

Turtles are part of the Phylum Chordata, Class Reptilia, and Order Testudines.

Their unique shell is made up of as many as 60 bones, divided into two sections: the carapace on their back and the plastron on their belly. The carapace and plastron are connected on the turtle's right and left sides by a bony bridge.

A turtle's shell is fashioned from bones originating in the skin, which fuse with one another and with the ribs, vertebrae, and parts of the shoulder girdle. In most species, large scales called scutes overlay the bones.

Consider reading: Common Snapping Turtle Shell

In some species, like box turtles and mud turtles, the plastron is hinged, allowing it to close on the carapace for extra protection.

Most Illinois turtles can withdraw their head and neck into the shell by bending their neck into a vertical S-shaped curve. Turtles usually have a prominent tail that varies in size with sex and species.

Here are the different species of box turtles classified within the genus Terrapene:

The genus name Terrapene was coined by Blasius Merrem in 1820, describing species with a sternum separated into two or three divisions.

Box turtles appeared abruptly in the fossil record, essentially in modern form. This suggests they may be a generalist species, making it complicated to establish how they evolved from other turtles.

The oldest finds of fossilized box turtles were discovered in Nebraska, dating back around 15 million years. These early finds resemble the aquatic species T. coahuila, indicating their common ancestor was likely an aquatic species as well.

Fossilized specimens of T. ornata and T. carolina date back around 5 million years. This shows that the main lineages of these species diverged within the Miocene era.

The only recognized extinct subspecies, T. c. putnami, was much larger than other species, with a carapace length of 30 cm.

On a similar theme: Box Turtle Reproduction

Box turtles can live up to 50 years on average, with some living over 100 years. Their growth is directly affected by factors like food, water, and illness.

The age of a growing box turtle in the wild is difficult to estimate by counting growth rings on their scutes. This is because their growth is influenced by many factors.

Box turtle eggs are flexible and oblong, measuring 2-4 cm in length and weighing 5-11 grams. The normal clutch size is 1-7 eggs.

In captivity and in the southern part of their range, box turtles can have more than one clutch per year.

A unique perspective: Are Box Turtles Going Extinct

Young box turtles, like Terrapene carolina carolina, have a unique appearance.

In their early years, the age of box turtles can be estimated by counting the rings on their scutes.

Rings on the scutes of T. triunguis can be used for this purpose.

Florida box turtles have been spotted in southeast Georgia.

You can use the following list to learn more about the different species of box turtles and their characteristics:

Turtles can be found in a variety of habitats, from woodlands to wetlands, and even in rivers and ponds.

Some species are highly adaptable and can thrive in different conditions, such as the snapping turtle, painted turtle, pond slider, and spiny softshell turtle.

Illinois' two terrestrial turtles, the eastern box and the ornate box, are associated with woodlands and prairies, respectively.

Most Illinois turtles are opportunistic omnivores, which means they eat both plants and animals. Even a snapping turtle's diet may include large amounts of plants along with the animal food it usually eats.

A few species are chiefly carnivorous or herbivorous, such as the softshells, which feed on aquatic invertebrates like aquatic insects.

Worth a look: Box Turtles of North America

Some turtle species are associated with specific habitats. For example, the eastern box turtle is found in woodlands, while the ornate box turtle prefers prairies.

Rivers are the favored habitat of several species, including the smooth softshell turtle, alligator snapping turtle, and northern map turtle. These turtles thrive in the water and can be found swimming or basking in the sun.

Blanding's turtles are commonly associated with marshes, where they can be found grazing on vegetation. Mud turtles, on the other hand, tend to frequent temporary ponds or wetlands.

The snapping turtle is highly adaptable and can thrive in a variety of habitats and conditions. This is likely due to its ability to eat a wide range of foods, including plants and animals.

Most Illinois turtles are opportunistic omnivores, eating a mix of plants and animals. Even the snapping turtle's diet includes large amounts of plants, in addition to its usual animal food.

Saltwater Turtles have a unique place in the world of North American turtles. They belong to the Superfamily Chelonioidea, which includes 6 species of sea turtles.

Living in the ocean, saltwater turtles have adapted to a diet that consists mainly of seaweed, seagrass, and jellyfish. They've been known to dive to great depths in search of food.

Some species of saltwater turtles can grow quite large, with adults reaching up to 8 feet in length.

Box turtles are found in a variety of habitats, including mesic woodlands, grasslands, and even semideserts with rainfall in the summer.

Some species, like the Coahuilan box turtle, are found in specific locations, such as the Cuatro Ciénegas Basin in Coahuila, Mexico, where they inhabit marshes with permanent water and various types of cacti.

Prior to hibernation, box turtles tend to move further into the woods, where they dig a chamber for overwintering, with some species digging chambers up to 50 centimeters deep.

In more southern locations, turtles are active year-round, as observed for the Coahuilan box turtle and the eastern box turtle subspecies T. c. major.

The location for overwintering can be up to 0.5 kilometers from the summer habitat and is often in close proximity to that of the previous year.

Some box turtles, like the ornate box turtle, are more adaptable and can be found in a range of habitats, from woodlands to grasslands.

In Illinois, only 11 percent of the original vegetation remains intact due to human activities like deforestation and wetland drainage. This drastic alteration has had a major impact on the state's wildlife and plants.

Five of the state's 17 turtle species are endangered, including the alligator snapping turtle and the spotted turtle. Two species, the ornate box turtle and the smooth softshell, are threatened.

The loss of wetlands is a significant cause of decline for three threatened turtle species. Siltation and channelization of Illinois rivers have also affected other species.

Snapping turtles and softshells are often sought for food in Illinois, and a growing demand for turtle meat and products in Asia has led to poaching. A special license is needed to collect turtles in Illinois for commercial purposes, but the high asking price makes poaching tempting to some people.

The keys to conserving Illinois' turtles are enforcing current protective laws and setting aside and maintaining clean, aquatic, and terrestrial habitats. If these guidelines are followed, turtles can remain in Illinois' forests, prairies, wetlands, and waterways for many years to come.

The Eastern box turtle has been declining due to anthropogenic factors and disease, including a polymicrobial necrotizing bacterial infection. This infection has been linked to over 50 box turtle deaths in Illinois.

Sniffer dogs have been trained to find and track box turtles as part of conservation efforts.

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Turtles of North America can live a long time, with some species surviving up to 70 years in the wild. Aquatic turtles, in particular, have been known to live for 40 to 70 years, while terrestrial species like the eastern box turtle can live for 100 years or more.

The largest Illinois turtle is the alligator snapping turtle, which can grow up to 30 inches in length and weigh over 250 pounds. Some specimens have even been recorded to weigh as much as 160 pounds.

Many species of turtles have a unique way of determining the sex of their young, known as temperature-dependent sex determination (TSD). This means that the sex of the embryo depends on the temperature within the nest at a critical period.

In Illinois, turtle eggs typically take about two months to hatch. Some species, like the painted turtle, may overwinter in the nest and not move to water until the next spring.

Consider reading: Where Are Leatherback Sea Turtles Found

Here's a rough breakdown of the different types of turtles found in North America:

Some species of turtles, like the eastern box turtle, may have poisonous flesh due to storing toxins from poisonous mushrooms they eat. The flesh of these turtles should be handled with care.

If you're considering keeping turtles as pets, there are a few things to keep in mind. Box turtles, for example, are not recommended for small children because they can be easily stressed by over-handling.

Box turtles require a lot of care, including a varied diet and consistent exposure to light. Without these, a turtle's growth can be stunted and its immune system weakened.

Three-toed box turtles are often considered the best ones to keep as pets since they are hardy and seem to suffer less from being moved into a new environment.

If you do decide to keep box turtles, make sure to protect them from household pets, like dogs and cats, which can injure them.