What is a Turtle?
Is it a Turtle or Tortoise?
Turtle Anatomy Body Parts
Types of Turtles/Tortoises
What is a Turtle?
Turtles are apart of the class called reptile (Reptilia). Reptiles can be described as cold-blooded (Ectothermic: metabolism that is controled by the surrounding environment) animals that have scales or scutes on their skin, lay shelled eggs, breathe air tetrapods (having four legs or descended from four legs). Turtles and tortoises then get grouped into Chelonians (Chelonia superorder), and again into the order Testudinidae for tortoises and Testudines for turtles.
Turtles are some of the oldest of the Chelonians (snakes, lizards, turtles) as the first turtles are thought to be first date back 200 million years. Today, there are around 300 species and a handful of these have found their way into the pet turtle industry.
The classification of turtles can split up into two separate groups, Cryptodira and Pleurodira; respectively speaking, those having necks that move vertically and those that move side to side. Ten turtle families fall into the Cryptodira groups while just two families live in the Pleurodira. Bellow is how it breaks down.
- Dermatemys mawaii (C. American River Turtle)
- Carettochelys insculpta (Pig-Nosed)
- Platysternidae megacephalum (Big-Headed)
- Dermochelys coriacea(Leatherback)
- Chelydra serpentina (Snapping)
- Macroclemys temminckii (Aligator Snapping)
- Chelonia (Green/Flatback)
- Lepidochelys (Ridley)
- Caretta (Loggerhead)
- Eretmochelys (Hawksbill)
- About 12 Mud Turtles
- About 12 Musk Turtles
- About 24 Soft Shelled Turtles
- About 50 Tortoises
- About 90 Aquatic Turtles
What is the Difference between a Turtle and a Tortoise?
Sometimes it’s difficult to determine whether a turtle is in fact a turtle, or, if it’s actually a tortoise. Both of these separate animal families share many very similar physical characteristics, and only a few traits that differentiate the two. There are of course wild card species that go against what in theory they should look like based what others in their family look like. It gets even harder to distinguish between individual species within the family as there might only be very subtle differences.
Furthermore, more confusion arrises when we humans can’t seem to agree on what is what in regards to terminology. Tortoises can easily be grouped in with turtles. A good example is the Box turtle. In America, that is what they are called, but in Europe, they are referred to as Box Tortoises.
In general, the best way to determine if it’s a turtle or a tortoise you are trying to identify is to know a few rules that apply to the majority of their respective families. Turtles need water to survive. When we say water, we mean they need water for more than just drinking; turtles are aquatic or semi-aquatic. This means that turtles live in and out of water. The exception is the box turtle, who have thicker skin that retains water like tortoises. Tortoises are terrestrial animals, meaning they live on land and don’t require water (aside from drinking) to survive. The exception to this is the Hingeback tortoise who needs a high humidity environment to survive.
Not ever turtle will fit this description but the main characteristics that show that a chelonian is a turtle and not a tortoise include the following bellow. (Some exceptions include the many number of box turtle species
- Live in and out of water
- Feet have claws more so than toenails
- Might have webbed like feet or flippers
- Tend to have lower pitched shells
- Might lack a plastron
- Might lack scutes (soft shelled)
Again, there are a few exceptions but the following are the traits that describe the characteristics that most tortoises will have and turtles will not. ( A few exception: hingebacks need water; pancake tortoises have a flat like shell.)
- Live exclusively on land
- Have thicker skin that helps retain water
- Feet have toenails more so than claws
- Tend to have higher pitched shells
See the anatomy graphic bellow to understand the parts of a turtle or tortoise.
A turtle shell provides shelter and protection from predators and threats. The shell consists of two parts or several bones fused together; the top part called the carapace and the underside called the plastron. The top section is connected to the turtle’s vertebra and the plastron is connected by the rib cage. The two parts are connected to each other by what is called the bridge.
Some tortoise and turtle species have shells that are hinged; meaning they have the ability to close up. Typically the hinge is on the front half of the plastron but the hinge tortoise has a hinge on the back half of the carapace. In addition to hinges on a shell, there are characteristics of a shell that can help you determine the sex of the chelonian. A flat plastron can mean its a female, while a concave one can mean it’s a male.
Unlike a hermit crab, turtles and tortoises can not leave their shells, they are connected to them for life. When a hermit crab grows, it needs to leave its shell and upgrade to a larger one. Turtle shells on the other hand grow with the turtle. Occasionally a shell won’t grow at the same rate as the turtle and this can lead to a disfigured turtle. In captivity, theses odd balls can still go on to live a happy life.
Scutes are protective plates that cover the shell of a turtle or tortoise. They consist of the same material that makeup finger nails, keratin. The top section of scutes are called the vertebral scutes; the outer most ones are called the marginal scutes and the ones right above the head are called the nuchal scutes. Some species lack the nuchal scutes while some have no scutes what so ever. These species of turtles that lack these protective shields on their shells are called soft shelled turtles, which is a flexible and leathery shell.
As stated previously, aquatic water turtles have softer skin that requires an external water sources to stay hydrated. Without water, the skin will dry up and create turtle health problems. A tortoise’s skin is thicker and is designed to help retain water.
The skin of a turtle looks scaly similar to their reptile cousins and like other reptiles, all tortoises and turtles shed their skin. The skin tends to come off in patches; so if you observe patches of skin falling off or floating in the water, don’t be alarmed, this is perfectly normal.
The feet of turtles and tortoises make telling the difference between the them a bit easier. Aquatic water turtles will either have webbed feet or even flippers in the case of sea turtles. These flippers and webbed feet make it easier for them to swim through the water. Even though their feet look more for swimming, they still have claws to some extent. These claws help the female turtles dig breeding nests. Some males turtle species have longer claws to help hold their mates while breeding.
Box turtles and tortoises have thick rough looking skin on their feet. These turtles have short stumpy feet that keep them low to the ground. Larger tortoise species on the other can have bigger feet that can look like tiny elephant feet, which of course are still pretty big. Instead of claws, these tortoises have toe nails which meant for digging.
Turtle necks come in a range of lengths. Some species have necks long enough to get them named snake necked turtles. A longer neck on a turtle allows it to reach up out of the water to breathe and also to grab a bit to eat as it swims by. A Long neck on a tortoise on the other hand allows it to reach up and grab leaves on taller shrubs. This physical feature can become a necessity in geographic locations that have scarce vegetation.
There are two types of necks found on turtles and tortoises. The first type of neck is one that moves vertically and might also be able to retract into the shell given the turtle is a species that has that ability. This type of chelonian fits into the Cryptodira division. The other type of neck moves side to side. Instead of tucking in their heads in, they tuck them around the sides of their shells. These turtle types fit into the Pleurodia division.
Like birds, turtles and tortoises have beaks too. The reason they are equipped with beaks are because they lack teeth. A beak acts as a tooth that helps a turtle rip and chew its food; wether that be green vegetation or a grub or bug.
Even with no teeth, a bite from a turtle can be painful. You might get a strong pinch from a box turtle that bites but if you were unfortunate enough to get a bite from a snapping turtle, you could lose a finger. If you find yourself with a finger trapped in the mouth of a turtle, submerge the chelonian under water; it will let go either because you caught it off guard or because it needs to breathe.
The eyesight of a turtle is as good if not better than that of a human being. It’s thought they see best at far distances and less so up near. They can also see in color; mainly in the red spectrum of light. Having good eyesight helps them avoid predators and threats as well as spot their own species.
Sea turtles, snapping turtles and most aquatic species can see very well underwater, as well as we can see on land. It’s said that these turtle types might have the opposite effect being able to see in and out of water. Their eyesight on land can best be described as what we humans see like when we open our eyes under water.
While Chelonians don’t have outer ears, some have ear openings that lead to the inner ear. Turtles and tortoises have even less than that. What they have is called a tympanum which acts as its hearing organ. For this reason, they hear low frequency sounds; meaning, turtles don’t hear well. The extent of their hearing deals more so with vibrations than actual sounds.
Types of Turtles and Tortoises
For even more of a breakdown and description of the types of turtles and tortoises, see the following: