Have you thought of the Tortoise vs. Turtle difference? Sometimes, people use these words interchangeably because of their similar characteristics. It is understandable because it can be hard to grasp that all tortoises are turtles, but not all tortoises are turtles. It also extends to land turtles- they are not tortoises.
On a higher level, both are from the Testudines order but belong to different families. The tortoise family is Testudinidae, and turtle species belong to Cheloniidae. All tortoises live on land, while turtles live across the world's oceans. Let’s explore more differences between these slow-shelled creatures.
What are the differences in characteristics between tortoises and turtles?
Depending on the species, there are various differences between the size of a turtle and a tortoise.
Turtles can be massive, with marine turtles being leatherback, green sea turtle, and loggerhead sea turtles, while some of the smallest species include the softshell and snapping turtles. The leatherback turtle weighs a minimum of 770 pounds, the green sea turtle weighs a maximum of 400 pounds, and the loggerhead sea turtle weighs 350 pounds.
The African spurred tortoise has a standard weight of 100 pounds and a length of 30 inches, while the Aldabra tortoise can grow up to 550 pounds and is 4 feet long.
Read more: Turtle Facts.
Sea turtles and tortoises are both shelled reptiles. However, there are some differences in their shell structures. A tortoise shell is dome-shaped and made of several layers of keratin, a substance similar to human nails.
The bottom layers of the domed shells contain living blood vessels formed from the ribs, vertebra, pelvis, and sternum, while the outer layers of the domed shell are dead. The dead keratin on the outer layers form scales known as scutes. As the domed shell grows, a new layer of keratin scale forms.
A sea turtle has a streamlined shell. Different turtle species have different shell compositions than tortoises with domed and heavy shells. For instance, leatherback sea turtles, softshell turtles, and fly river turtles have modified shells. They have tough, leathery shells instead of hardened keratin.
Shells with α keratin are soft, while those with α and β keratin are brittle and hard. A turtle's bony shell makes swimming easy, while a tortoise's shell is not adaptable to living underwater.
3. Limbs and Movement
Another difference between a turtle and a tortoise is their limbs and how they move around. Sea turtles have flippers or webbed feet. Long digits are fused throughout the flipper, with only one or two claws on each foreflipper.
Their hind flippers serve as rudders, stabilizing and directing the turtle as it swims. The hind flippers of some species are dexterous at digging nests in the sand. Land turtles have rounded webbed feet.
The tortoise's limbs resemble a club, with rounded feet and invisible toes. The hind legs have flared feet and no visible toes. The tortoise’s sturdy legs help it stroll on land, while turtles are more agile with their flippers in water than on land.
Read more: Tortoise Facts,
All tortoise species can retract their head and limbs. However, not all turtles can retract their heads and limbs. Tortoises have flexible necks and limbs that facilitate easy retraction. They also have a plastron, which seals the entrance of the retraction space to protect them from external forces completely.
Sea turtles can’t because their flipper anatomy doesn’t allow it. However, land turtles can retract their limbs in two ways.
The first retraction method is similar to that of a tortoise. They can retract their head back into their shells in a straight line. Side-necked turtles retract their neck by folding them sideways into their shells.
Another difference between turtles and tortoises is their preferred habitats. Most adult turtle species prefer to live in shallow areas of coastal waters, bays, lagoons, and estuaries, while some explore the open sea. You will mostly find turtle hatchlings in the sea, bay, and lagoon areas.
Tortoises live above ground in dry and wet forest areas, grasslands, and savannas. Some species, however, prefer to live underground. One example is desert tortoises, which burrow deep into the ground to escape extreme hot or cold weather.
Turtles and tortoises have different diets. Not all turtles have the same diet. They can be carnivorous, herbivorous, or omnivorous.
Some species, like the green sea turtle, change their eating habits as they age. The shelled reptiles eat meat from hatchlings until they reach juvenile size before switching to an herbivorous diet.
Freshwater turtles eat worms, snails, small mammals, turtles, water plants, and fish, while tortoises feed on plants.
Turtles and tortoises are in various places across the world. You will find an abundance of turtle species in the Indian Ocean, South America, Congo Central, northern American deserts, South Africa, the Atlantic forest of Brazil, and the Mediterranean basin.
You will find giant tortoises in the Galapagos islands, with the Aldabra giant tortoise living in Mauritius and Seychelles. Tortoises are scattered around the United States1, Thailand, Malaysia, India, and Australia.
Turtles and tortoises have different reproductive behaviors. Female turtles spend all their time underwater but come to land between May and September to lay eggs on land. She uses her flippers to dig a hole in the ground before laying.
However, tortoises lay eggs underground. These shelled reptiles produce eggs with a leathery texture. Female tortoises can hold sperm for several months so they can lay fertilized eggs without intercourse2.
Male turtles reach sexual maturity as early as seven years of age. They use their sharp claws on their webbed feet to hold onto the female turtle during mating. Turtles mate underwater, while tortoises copulate on land.
Furthermore, a female tortoise can lay up to 26 eggs, while a female turtle can lay up to 500 eggs. The quantity of eggs laid depends on the species.
Tortoises live longer than turtles. They can live up to 80 years, while turtles have a maximum lifespan of 50 years. It varies according to the species. For instance, the snapping turtle, box turtle, and Kemp's Ridley turtle have a lifespan of 30 to 35 years.
Loggerhead and leatherback turtles live over 70 years. There are many reports of tortoises living over 100 years in captivity. Jonathan, a giant tortoise, holds the record for the oldest turtle at 190 years old.
Threats And Conservation Status
About 44% of turtles and tortoises are critically endangered. The IUCN accessed 270 turtle species and classified 68 turtles as critically endangered, 46 as endangered, 56 as vulnerable, and 35 as near threatened.
They also assessed 58 species of tortoises and classified 20 species as critically endangered. Seven species are endangered, 15 are vulnerable, and two are near threatened. The IUCN declared 129 species with a fast-declining population. Twenty-one species are stable, while eight species are increasing their population.
These vulnerable species include the box turtles, northern river terrapins, giant tortoises, and map turtles. They are nearly extinct because of marine plastic pollution, rising ocean temperatures, and oil spills. Human activities like poaching for meat and eggs and deforestation lead to habitat loss.
Several conservation efforts are employed towards saving several species of these marine species. June 16 is World Turtle Day, dedicated to protecting these unique animals with streamlined shells.
Conclusion: Tortoise vs. Turtle
There are several differences between a turtle and a tortoise. These two unique creatures have different lifespans, limbs, and movement patterns. They also live in entirely separate habitats.
Unfortunately, both species are threatened with extinction. You can help by raising awareness and protecting them from human activities causing their decline.
Mittermeier, R. A., Van Dijk, P. P., Rhodin, A. G. J., & Nash, S. (2015). Turtle Hotspots: An Analysis of the Occurrence of Tortoises and Freshwater Turtles in Biodiversity Hotspots, High-Biodiversity Wilderness Areas, and Turtle Priority Areas. Chelonian Conservation and Biology.
Kubisch, E. L., & Ibargüengoytía, N. R. (2021). Reproduction. Elsevier eBooks.