How Hard Is A Turtle Shell

A turtle’s shell is one of the more unique evolutionary traits when it comes to reptiles. Formed over millions of years, the shell provides an excellent defense mechanism against predators. Since turtles generally lack speed and agility, their shells are a very important defense mechanism that keeps them alive. In today’s article, we are going to discuss everything you need to know about the turtle’s shell, and how hard it really is.  

What material is a turtle’s shell made of?

A turtle’s shell is comprised of a web of connected bones that fuse together the turtle’s spine and rib cage. The top portion of the turtle’s shell is covered by square plates called scutes. They add an extra hard layer to the turtle’s shell, and are made of a material called keratin. Keratin is the same material that fingernails are made of. 

Can a turtle leave its shell?

No. A turtle is unable to leave its shell because the shell is connected to their spinal cord and rib cage. Unlike other sea animals with shells, the shell of a turtle is more of an extension of their body instead of a “temporary home.” An empty turtle shell usually means that the turtle was eaten by a predator. As the shell is very hard and provides very little nutritional value, predators usually only eat the body of the shell and leave the shell untouched.

How hard is a turtle shell?

A turtle shell is extremely hard, and can withstand thousands of pounds worth of pressure. The average turtle shell has a fracture toughness of 36.4MPa m1/2. Fracture toughness measures the amount of force needed to fracture through a surface. For comparison, a turtle shell is stronger than aluminum, which only has a fracture toughness of 22MPa m1/2. Titanium is harder than a turtle shell, with an average fracture toughness of 95MPa m1/2.

Do animals eat turtles?

Yes, there are plenty of animals that eat turtles. However, the majority of these animals are scavengers (animals that eat the turtle after it dies), or they eat the turtle without crushing the turtle’s shell. They eat the turtle by fitting their mouth or paws inside the turtle’s shell. However, there are very few predators that have the mobility to achieve this. For this reason, most turtles are safe if they can retract their head, legs, and tail back into the shell. 

Which animals can eat turtles?

Now you are probably wondering what animals are able to crack a turtle’s shell. 

Alligators/Crocodiles

For land turtles, the biggest threat are alligators and crocodiles. Both these animals have jaws that can crush a turtle’s shell. An alligator’s jaw can apply 2,980 psi [pounds per square inch], while a crocodile’s jaw can apply  5,000 psi. While alligators and crocodiles can eat turtles if they want to, they can sometimes befriend turtles. This is because they don’t like the taste of the turtle’s shell, which is very bony and low in nutritional value. This is why you will often see turtles swimming near alligators or crocodiles without a worry. 

Honey badgers

Surprisingly, honey badgers are another land animal that is strong enough to break through a turtle’s shell. Unlike alligators and crocodiles, honey badgers like the taste of turtle’s shells. Honey badgers have very strong and sharp teeth that are able to penetrate the turtle’s shell. 

Whales/Sharks

When it comes to sea turtles, the main animals that can break a turtle’s shell are whales and sharks. Tiger sharks are a common predator of sea turtles, and killer whales frequently eat leatherback turtles. Sea turtle’s tend to have softer shells because their shells must be more flexible underwater. 

Birds

Why are birds on the list? How in the world do birds crack a turtle shell? Well, birds are able to crack a turtle shell based on their ingenuity, and not because of their jaw strength. It is not uncommon for birds to pick up a turtle and carry it to a very high altitude. They then drop the turtle, which usually results in the shell cracking upon impact with the earth. There are a couple videos of this which you can find on youtube. 

Scavengers

There are also a bunch of animals that frequently eat turtle’s eggs and hatchlings. These animals include birds, raccoons, foxes, crabs, and dogs. For this reason, only 10% of turtle eggs survive.

Should you pet your turtle’s shell?

Petting a turtle’s shell is a controversial topic. Some people believe it is an invasion of privacy and nuisance for the turtles, while others believe turtles think petting feels good. There are a lot of videos on the internet that show a happy turtle being pet by their owner. A turtle does have some feeling in their shell.

If you want to pet your turtle, the key is to start soft and read your turtle’s body language. If you start petting your turtle and they immediately put their arms or head back in their shell, they most likely feel uncomfortable. This is also the case if your turtle starts to walk away from you when you start petting them. On the other side, there is a chance your turtle really enjoys the petting. In this case, they will probably keep inching closer and closer to your hand.

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