Types of Turtles

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Turtles are reptiles of the Order Testudines, differentiated from other reptiles by the presence of a shell, which at its most basic level consists of a carapace (top portion) and plaston (bottom portion).

A presentation on the different types of turtles commonly takes both an informal and a formal or scientific tone.

Informally, when most people think turtle, they think of three types of turtles, based on their primary habitat: fresh water turtles; tortoises; and sea turtles.

Formal classification of turtles follows a similar logic, albeit with a more developed organizing system.

Scientists differ slightly in the classification of the world's turtles. The Tortoise and Freshwater Turtle Specialist Group at the IUCN recently published a revised taxonomy of the world's 454 turtle species (317 species and 137 subspecies).

From a big picture point of view, turtles are first divided into two sub-orders, Pleurodira and Cryptodira, defined primarily by neck characteristics.

The smaller of the two suborders, Pleurodira, or Side-necked turtles, get their name based on the fact that their necks move horizontally and are places on the side of the shell for protection. Pleurodira divide into three families:

• Chelidae - Found in Australia and New Guinea
• Pelomedusidae - Found in Sub-saharan Africa and Madagascar
• Podocnemidae - Found in northern South America and Madagascar

Cryptodira, or hidden neck turtles, get their name from the fact that their necks move vertically and into the shell for protection. Thirteen Cryptodira families are recognized:

• Carettochelyidae (Pig-nose Turtles)
• Cheloniidae - (Sea Turtle)
• Chelydridae - (Snapping Turtles)
• Dermatemydidae - (River Turtles)
• Dermochelyidae - (Leatherback Turtles)
• Emydidae - (Pond Turtles)
• Geoemydidae - (Mostly Eurasian Freshwater Turtles)
• Kinosternidae - (American Mud and Musk Turtles)
• Platysternidae - (Big-headed Turtles)
• Testudinidae - (Tortoises)
• Trionychidae - (Softshell Turtles)

Fifty-five turtle species, consisting of six different families, make their home in the United States, with the majority of species found in the Southeastern part of the country. The freshwater turtles belong to four families.

• The Family Emydidae contains the largest number of fresh water turtle species such as box turtles, pond turtles and river turtles. All twelve species of Map Turtles were recently listed in CITES Appendix III, meaning cross border trade in these species requires a permit.
• Family Chelydridae - The Alligator and Common Snapping Turtles represent this species in the United States. The Alligator Snapping Turtle is also listed on CITES Appendix III.
• Family Kinosternidae - Mud and Musk Turtles
• Family Trionychidae - Three species of softshell turtles in United States - Smooth Softshell, Spiny Softshell and Florida Softshell

Information about the four tortoise species and seven species of marine or sea turtles that swim the world's oceans can be found by clicking on a links in the box on the right.

© 2007-2009. Patricia A. Michaels