How to Tell the Difference Between Turtles and Tortoises

Most folks lump turtles and tortoises together under the vague category of “very slow reptiles that carry their houses on their backs.” However, there are some subtle differences between turtles and tortoises—and knowing them will make your life much easier when your curious grade-schooler asks you this question out of the blue.

Instructions

Difficulty: Moderately Easy

1. Turtles and tortoises belong to the same division of reptiles. Along with yet a third variant on the big-shell theme—terrapins—turtles and tortoises belong to a division of the reptile family called the “chelonians.” Thanks to the vagaries of taxonomy, all tortoises (which occupy their own sub-classification of chelonians) are turtles, but not all turtles are tortoises.
2. Turtles live in an aquatic environment. The average turtle spends most of its life in oceans, lakes or rivers, and it has evolved adaptations that reflect this lifestyle (for example, webbed feet with which it can swim more easily and a streamlined body). Usually, turtles only venture onto dry land when it’s time to lay eggs—and when the eggs hatch, the baby turtles head straight to the water.
3. Tortoises are primarily land-dwelling creatures. Because they don’t have to be hydrodynamic, tortoises tend to be stumpier-looking than turtles, with stubby, strong legs and a more rounded body shape. Tortoises that live in hot climates usually stay underground during the day (remember, reptiles are cold-blooded and need to protect themselves from extreme temperatures).
4. Terrapins are a kind of hybrid between turtles and tortoises. Like their cousins, the amphibians, terrapins spend equal amounts of time in the water and on land, and they can always be found in (or near) ponds, lakes and rivers. Terrapins are most often considered to be more closely related to turtles than to tortoises.

Tips & Warnings

• Confusingly, different countries have different ways of referring to turtles and tortoises. In England, freshwater chelonians are called terrapins, while ocean-dwelling chelonians are called turtles (as they are in the U.S.). Things are even worse in Australia: only sea turtles are called turtles, while aquatic (but not sea-dwelling) chelonians are called tortoises. What we call “tortoises” in the U.S. don’t exist in Australia, which has no land-dwelling chelonians. Got that?