It’s not always clear what makes a turtle a turtle and a tortoise a tortoise. In fact, many people use the names interchangeably.
This article covers the significant differences between the two and will provide you with all the information needed to tell them apart.
Taxonomic Classification and Evolutionary Background
The best place to start when understanding the differences and similarities between tortoises and turtles is to look at their evolutionary history and classification.
Scientific Classification
Both tortoises and turtles belong to the Order of reptiles called Testudines. There are 14 families in this clade. Tortoises include just a single family, Testudindae, whereas turtles comprise the remaining 13 families.
There are just 46 species of tortoise across 15 genera. Conversely, there are over 350 turtle species across 75 genera.
Evolutionary Insights
Testudindae, is embedded within the turtles. This means that all tortoises are turtles, but not all turtles are tortoises. Turtles first appeared round 230 million years ago, from which tortoises evolved 175 million years later.
Physical Characteristics
One of the easiest ways to tell the difference between tortoises and turtles is by looking at their physical characteristics, specifically their shells and limbs.
Shell Structure and Shape
The shells of both tortoises and turtles follow the same, basic structure. The dorsal shell is called a ‘carapace’ and is located above the body. The ventral shell is called a ‘plastron’ and is located underneath the body.
Both parts of the shell are connected to protect their body. The bony, plate-like scales that visibly overlay the top shell are called ‘scutes’ and act as protective armor.
Due to their aquatic lifestyle, turtles have evolved stream-lined shells which are fairly flat, thin and light. Turtle’s shed their scutes to keep their shells smooth.
Tortoise shells are heavier and domed in shape, due to individual scutes growing on top of one another.
Limbs and Locomotion
Tortoises are generally larger and heavier than turtles and their legs are designed to carry them across land. They have stocky, club-like limbs that somewhat resemble elephant legs.
Conversely, the front limbs of turtles have evolved into flippers to propel them through the water. Their back limbs resemble webbed feet and act as rudders.
Habitats and Lifestyle
Turtles and tortoises have very different lifestyles and so the habitats they frequent and food they eat are vastly different.
In the wild, Turtles are aquatic animals that frequent coastal waters worldwide, with females only coming onto land to lay their eggs.
Tortoises live in a variety of terrestrial habitats ranging from deserts to mountains to jungles.
Diet and Feeding Habits
Sea turtles are omnivores and will consume various marine life, including algae, fish and crustaceans. The majority of tortoises are herbivores and consume only vegetables, grasses and occasionally fruit.
Reproductive Behaviors
When it comes to reproduction life stages, tortoises and turtles are not too dissimilar.
Courtship tends to be an aggressive affair in both, with males circling, biting and ramming into mates.
Female turtles and tortoises can retain sperm for a few years. Both lay their eggs in terrestrial nests that they dig from sandy soil. Neither provide parental care.
Lifespan and Growth
Tortoises have an average life expectancy of ranging from 40 to 150 years. At the time of writing, the oldest tortoise is a Seychelles giant tortoise called Jonathan, who turned 191 at the end of 2023. On the other hand, turtles generally live between 50 and 100 years.
Both tortoises and turtles follow similar growth stages, beginning with eggs, to hatchlings, to juveniles, to adults.
Conservation Status and Human Impact
Largely due to climate change and human activity, there are numerous threats throughout the world faced both by tortoises and turtles.
Threats to Survival
Almost all species of sea turtle are classed as endangered and significant threats include:
- Climate change
- Pollution
- Vessel strikes
- Habitat loss
- Commercial fishing
- Poaching
Roughly half of the world’s tortoise species are under threat of extinction, and significant threats include:
- Habitat loss
- Vehicle collisions
- Pollution
- Exposure to domestic diseases
- Urbanization
- Poaching
Conservation Efforts
It is vital that funding continues on a world-wide scale, both to educate and raise awareness of the importance of these animals and their current threats. Thankfully, several conservation efforts and legislation are in place to protect turtles and tortoises.
Many areas where these species frequently occur are now protected, including the Galapagos Islands in Ecuador. Most notably, they are protected under the Endangered Species Act in the United States.
Plus, there are many rehabilitation programs in place worldwide to increase population numbers.
Care Requirements as Pets
There is a lot to learn about tortoise and turtle husbandry, and they should always be considered a lifelong commitment. Once understood, looking after them is straightforward enough and they can make excellent pets.
Enclosures and Diet
The habitat requirements for turtles and tortoises differ greatly. Turtles require a Turtle Aquarium that is filled 2/3 with water and has 1/3 dry land.
Tortoises on the other hand, require a terrestrial enclosure. Both favor warm habitats, so heat and UV lamps will need to be provided unless your climate is similar to their natural habitat.
Another major difference is diet. Tortoises are herbivores, so you can feed them a variety of vegetables and plants.
However, as omnivores, turtles need animal-based food sources, and you can buy commercial turtle food, fish pellets and prepared vertebrates or invertebrates.
The last major care difference is regarding hibernation. Generally, captive turtles do not go into hibernation. However, it’s recommended to hibernate many species of pet tortoise, so it’s important to have a hibernation enclosure.
Common Health Issues
Since tortoises and turtles share a similar anatomy, they are also prone to several common health concerns. In most instances, these problems usually arise because of poor husbandry and improper care.
As a responsible keeper, you will no doubt want your pet to thrive, so it’s worthwhile getting familiar with these common problems. Understanding is key to avoidance; plus, you’ll be better able to spot the signs and act quickly if health issues arise.
Shell-Rot
This fungal or bacterial infection affects the keratin layer of the shell causing it to become soft or discolored. In advanced cases, the shell might emit a foul odor.
It often starts from a minor injury or poor environmental conditions, such as excessive moisture or unclean habitats.
Treatment involves cleaning the affected areas and applying topical anti-fungals or antibiotics. In severe cases, your veterinarian can prescribe oral medications.
Mouth-Rot (Stomatitis)
This fungal infection can be caused for a few reasons including by poor diet, injury, stress, or unsanitary conditions.
As a result, tortoises and turtles can have difficulty eating because of inflamed and possibly bleeding oral tissues.
It’s essential to get veterinary care if you suspect Mouth-rot, as treatment may require cleaning the oral cavity and removing dead tissue. In all instances your pet will be prescribed antibiotics or anti-fungals. If your tortoise becomes infected with Mouth-rot, I strongly recommend a review of your pet’s diet and a deep-clean of their enclosure.
Gastrointestinal Parasites
Parasites can be common in tortoises and turtles due to contaminated food or exposure to infected feces and are often exacerbated by stress or overcrowding.
Symptoms include weight loss, diarrhea, or lethargy and diagnosis is typically made via fecal examinations. Your veterinarian will need to prescribe anti-parasitic medications.
To avoid a recurrence, deep clean your pet’s enclosure and spot clean uneaten food and feces daily. If you have more than one turtle or tortoise you may need to expand their housing or provide individual enclosures to minimize stress and help control outbreaks.
Vitamin A and D Deficiencies
Vitamin D deficiencies are directly related to a lack of UV light. As a result, tortoises and turtles cannot effectively absorb calcium, which can cause soft shells or skeletal deformities, leading to metabolic bone disease (MBD).
Swelling of the eyes and respiratory problems are most often associated with vitamin A deficiencies.
In severe cases a veterinarian might need to administer injectable vitamins. However, it’s possible to prevent vitamin deficiencies by supplementing your pet’s diet with appropriate vitamins 2-3 times per week and ensuring they have access to adequate UVB light.
Citations
- University College London – Testudines
- Encyclopaedia Brittania – Turtle and Tortoise Differences
- San Diego Zoo – Conservation
- Nashville Zoo – Physical Characteristics
