What’s the difference between a tortoise and a turtle?

Tortoises and turtles are very often confused as the same animals. Both have shells, both move comparatively slowly, and both have a beak more like a bird than a reptile. To most people, they are simply “that shelled thing giving me the evil eye from across the room.”

But what makes a tortoise a tortoise and a turtle a turtle? What is the difference between a tortoise and a turtle? In this article we will look at the differences between tortoises and turtles — and hopefully prevent at least a few family arguments at garden centres.

From the giant Aldabra tortoise that can reach the size of a small car and weigh more than 300kg, to the Egyptian tortoise that reaches roughly the same length as a pencil and weighs around 300 grams, every species shares this in common: tortoises are exclusively land-dwelling, or terrestrial, animals.

Their feet have a distinct elephantine appearance with thick, sturdy limbs designed for supporting heavy bodies over rough terrain. In simple terms, tortoise feet are built like hiking boots. They, for the most part, do not swim — and those that do generally swim with all the grace and confidence of a wheelbarrow falling into a pond.

From hot, arid deserts to humid forests and swamps, tortoises have evolved to occupy almost every terrestrial environment imaginable. Slow-moving, heavily armoured, and permanently carrying their house around with them, tortoises are essentially biological tanks with surprisingly strong opinions about garden weeds.

Turtles (including terrapins and sliders), on the other hand, have evolved feet that function more like flippers. In highly aquatic species, such as sea turtles, these limbs are extremely specialized for propulsion through water. Even semi-aquatic turtles possess webbed feet to aid in swimming.

The largest turtle species is the ocean-going Leatherback turtle, capable of reaching 6 feet in length and weighing over 450kg. The smallest is the tiny North American bog turtle which, at approximately 4 inches long and weighing just 28 grams, is small enough to make you question whether evolution briefly experimented with “pocket turtle.”

Another significant difference lies in diet. Tortoises are, for the most part (with a few omnivorous exceptions that deserve their own article), herbivorous. Feeding on leafy greens, weeds, flowers, grasses, hays, shrubs, and the occasional piece of fruit, tortoises have completely cornered the “grazing reptile” market. If it grows out of the ground and looks vaguely fibrous, there is a tortoise somewhere attempting to eat it.

Turtles are generally far more omnivorous, with some species evolving highly specialized predatory diets. One of the best examples is the alligator snapping turtle. This enormous freshwater species possesses a worm-like lure on the tip of its tongue. Holding its mouth open beneath the water, the turtle wiggles the lure to attract curious fish before snapping its jaws shut with alarming speed. Nature, apparently, decided that one turtle species should be part reptile, part bear trap.

Most other turtles and terrapins are opportunistic omnivores, feeding on fish, molluscs, aquatic invertebrates, greens, algae, seaweed, and aquatic vegetation. In captivity, many will also develop the impressive skill of splashing water directly onto the person feeding them. This is not scientifically necessary, but they seem committed to it nonetheless.

The easiest (and most pop culture) example we use is this:

• Master Oogway from Kung Fu Panda is a tortoise. Wise, terrestrial, slow-moving, and permanently carrying philosophical disappointment in his expression.
• Crush from Finding Nemo is a turtle. Aquatic, flippered, and somehow the reptilian embodiment of a surfer who definitely says “dude” unironically.

So while tortoises and turtles may look similar at first glance, they are highly specialized reptiles adapted for very different lifestyles. One evolved to roam the land grazing on plants; the other evolved to dominate rivers, lakes, swamps, and oceans. Both, however, still manage to look mildly offended whenever humans interrupt their day.