Turtles can be confusing animals, since they have characteristics that are traditionally associated with both reptiles and amphibians. For example, their smooth skin makes most people think of amphibians. But a turtle’s lack of metamorphosis as they grow is more akin to reptiles. So, are turtles reptiles or amphibians? Despite this jumble of features, turtles are actually reptiles and share much more in common with reptiles than most people realize.
The Short Answer: Turtles are Reptiles
Turtles are actually reptiles, although they are often confused for amphibians. Both turtles that live on the land and in water have key characteristics that denote them as reptiles. Turtles use their lungs for respiration and lay amniotic eggs on land, two markers of a reptile. (Even sea turtles lay their eggs on land.) And when these eggs hatch, the baby turtles are miniature versions of the adults. Turtles, like other reptiles, do not undergo a significant transformation in appearance as they mature.
Additionally, all reptiles have skin that will include either scales or scutes (a type of bony plate), both of which serve as defensive mechanisms. The turtle’s most distinctive feature, its shell, is made up of scutes. Scales and scutes protect reptiles from predators but also help them more easily thrive in their environments.
Reasons Why Turtles are Confused for Amphibians
There are many similarities between reptiles and amphibians and this overlap is what causes so many people confusion. In fact, if you’ve ever heard the phrase “going herping” or heard an animal called a “herp,” you’re hearing these similarities in action. Both reptiles and amphibians are classified as herpetofauna, and the study of reptiles and amphibians is called herpetology.
Some of the most well-known similarities are that both reptiles and amphibians are cold-blooded (ectothermic), lay eggs, are primarily omnivorous, and have excellent eyesight. Some anatomical similarities to note are that most reptiles and amphibians are vertebrate animals, lack external ear structures, use spinal segmental reflexes for movement, and have cloaca. Additionally, both reptiles and amphibians can be venomous or poisonous; reptiles can contain toxins in their teeth or nails, while amphibians typically secrete toxins through their skin. Because of these and other similarities, reptiles and amphibians also both thrive in similar environments. Reptiles and amphibians both prefer environments that are warm or hot with ample access to bodies of water.
Turtles also share some interesting physical characteristics with amphibians that lead to confusion. For example, without the presence of scutes (e.g., their shell), it would be markedly more difficult for people to visually identify turtles as reptiles. Typically, reptiles have drier, rougher skin while amphibians have smoother, moist skin. In this way, turtles look more similar to amphibians since they tend to have slick, wet skin.
Additionally, most reptiles have distinct nostrils and a vomeronasal organ, also known as Jacobson’s organ. This olfactory organ is located in the hard palate (e.g., roof) of the mouth and allows animals to detect chemicals in the air or environment. However, turtles do not have nostrils or a vomeronasal organ (neither do crocodiles).
Differences Between Reptiles and Amphibians
One of the biggest differences between reptiles and amphibians is that amphibians have a “bimodal” lifestyle. “Bimodal” refers to the two different stages in an amphibian’s life, each of which involves a unique method of movement. Another way to refer to this change is a metamorphic lifestyle.
Amphibians typically begin their lifecycle as aquatic animals and then transition into terrestrial or semi-terrestrial adult animals. A classic example of this is the frog: a frog’s life journey begins life as a tadpole using gills and then gradually transitions to its adult form and switches to lung respiration. Reptiles do not undergo a transformation between life stages: they begin and end their lifecycle as aquatic, terrestrial, or semi-terrestrial. Like other reptiles, turtles are born as a smaller version of their adult form and simply grow bigger as they age.
Another key difference between reptiles and amphibians is how they process air. Reptiles use their lungs to bring in air and oxygenate their bodies. But amphibians have different respiratory systems throughout their lifecycle, including gills, lungs, and their skin. Turtles are born with and continue using lungs throughout their life; they have no other means of respiration.
Some amphibians even use their skin to keep hydrated, which is another difference. Most reptiles take in water through their mouths, just like humans. For this reason, most amphibians have skin that is highly permeable and will feel moist to the touch. This skin will have a number of glands present, including mucous glands and even poison glands. Conversely, turtles and other reptiles have non-glandular skin that is less permeable and designed to limit water loss.
Difference Between Turtles and Tortoises
Besides being confused for amphibians, turtles are most commonly confused with tortoises (another reptile). However, there are also distinct differences between turtles and tortoises. The most important difference is that turtles can swim while tortoises cannot. This means that turtles can be terrestrial, semi-terrestrial, or aquatic, while tortoises are strictly terrestrial.
Because of this, turtles may have webbed feet or flippers, while tortoises have more rounded feet with nails. The skin of both animals is also different to better reflect their environments. Turtles will tend to have smoother skin reminiscent of the amphibians they are so often confused for. But tortoises will have drier, more leathery skin that clearly reflects their reptile status.
