Can a Turtle Outgrow Its Shell?

A turtle's shell grows with it throughout its life. Learn how a hard, protective shell can keep growing in this episode of BrainStuff, based on this article: https://animals.howstuffworks.com/reptiles/turtle-shell.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff
Lauren vogelbamb Here. Turtle is the common American English word
for the three hundred and fifty sum species of reptiles
known for their characteristic shells. Sometimes you might see, especially
in British English, distinctions between land based tortoises, freshwater terrapins,

(00:26):
and marine turtles. But today I'm talking about the whole
mess of them using the word turtle. Okay, okay. They
live in oceans, lakes, streams, forests, and deserts all over
the world except Antarctica. They might be in a yard
or pond near you, and those shells are amazing adaptations.

(00:48):
The shape of a turtle shell depends on the species
and the turtle's habitat. Most land dwelling turtles have a high,
domed shell, which helps protect them from the jaws of predators,
while most aquatic turtles have a more streamlined, flattened shell
that lets them glide through the water. Turtle's shells are
made up of two parts, the carapas, which is the

(01:10):
upper half on the turtle's back, and the plastrin, which
is the lower half under the turtle's belly. Structures called bridges,
fasten the two together. The turtle sides. They're generally bony,
but in soft shell turtles they're flexible. For the many
species of turtles able to retract into their shells, a
hinge joins the two halves together That allows the carapas

(01:31):
and plastron to close tightly when the turtle draws itself in.
Both the carapus and plastron are made of bone, including
about fifty to sixty rib and backbones in the upper
shell and a fusion of clavical and rib bones in
the lower shell. On the outside of the bone, each

(01:51):
shell half is covered in scoots, sometimes called shields, which
are overlapping pieces of keratin the same substance as human fingernail.
The scoots provide a protective coating. Most soft shelled species
don't have scoots, but they do have a layer of tough,
leathery skin. So a turtle's shell offers intricate skeletal protection.

(02:15):
But can a turtle outgrow its shell? Unlike a hermit crab,
a turtle isn't able to trade in one shell for
another if it's damaged or just doesn't fit anymore. Hermit
crabs will trade shells because they don't grow their own.
They find their shells in their environments. But a turtle's
shell never falls off and is never too large or

(02:36):
too small because it grows with the turtle. It's made
from the turtle's rib cage and spine, and it's attached
to the internal bones with the turtle's body. Just as
your vertebrae grow with you, are the same as true
for a turtle's shell. For most species, as the turtle
and its shell grow, the scoots on the shell shed

(02:57):
or peel away to make room for new, larger scoots.
The shedding is a natural process that takes place over time,
and individual scoots are cast off during daily activities like
swimming and basking in the sun. Because turtles are cold
blooded reptiles, they rely on external ways of heating and
cooling themselves. While basking is one way that turtles raise

(03:21):
their body temperature, it also helps them shed scoots by
drying them up, leaving them ready to fall off. Some turtles,
like the South American river turtle, lend each other a
hand in the shedding process. Well, they lend each other
a jaw by pulling loose scoots and algae off each
other's shells. This is done gently, though, since both pain

(03:42):
and pressure can be felt through the shell. When old
scoots aren't suitably shed, turtle shells can develop infection and disease.
In rare instances, scoots are shed too frequently, leaving the
bones of the shell unprotected and soft. Overabundant scoots, shedding
has been linked to larger problems like renal failure. Shell

(04:05):
health is also dependent on bone health. A metabolic bone
disease caused by inadequate calcium intake of poor exposure to sunlight,
as well as diseases of the liver, kidneys, and thyroid
can all result in soft or misshapen shell bones. Ulcers,
also known as shell rot, can cause permanent shell and
scute deformities. Shell disease doesn't occur as frequently as injury,

(04:30):
though fractured shells are common and happen when turtles are
hit by cars or attacked by other wildlife. Some veterinarians
are able to repair broken shells with bonding materials, but
one of the fantastic things about a turtle's shell is that,
since it's made of living materials, it can slowly repair
itself and regrow Today's episode is based on the article

(04:57):
can a Turtle Outgrow its Shell? On How Stuff Works?
Written by Maria Tremarchy. Brain Stuff is production of iHeartRadio
in partnership with HowStuffWorks dot Com and is produced by
Tyler Klang. Four more podcasts my heart Radio, visit the
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