The tortoise is a reptile that lives exclusively on
land. The name "tortoise" actually refers to the taxonomic
family testudinidae, and there are therefore a wide
variety of tortoises of different species. Tortoises
can be found throughout the world.
The tortoise is perhaps best known for its shell. However,
it is less well known that this shell actually consists
of two layers. The outer layer of the shell is hard
and made of scales, and conceals the inner layer, which
is made of bone. Most tortoise's vertebrae are fused
to their shells The shell consists of a top portion
that covers the turtle's back, and a lower portion that
covers its underside. These segments of the shell are
joined by a bridge at the tortoise's side.
If the tortoise is not known best for its shell, it
is known best for its speed, or lack thereof. Giant
tortoises move particularly slowly, with an average
speed of less than .2 miles per hour. The fastest speed
at which a tortoise has been recorded moving is five
miles per hour.
Tortoises use their shells as protection by withdrawing
their heads into them when they detect a threat. Their
eyes are also protected by heavy lids. Because of these
defensive adaptations, tortoises do not need to be able
to move exceedingly quickly. Tortoises also have poor
hearing, as good hearing is not a useful trait to the
Most tortoises are herbivores, subsisting on flowers,
leaves, fruit, grass, and weeds. Omnivorous species
also eat insects and the remains of dead animals. Tortoises
do not have teeth, and instead have a beak that they
use to bite into leaves and vegetation.
Tortoises can vary greatly in size depending on species.
The smallest tortoise, the speckled cape tortoise, measures
2.5-3.9 inches in length and 3.4-5.8 ounces in weight
on average, and the largest tortoise, the giant tortoise,
the Galapagos tortoise, may measure over 5 feet in length
and up to 550 pounds in weight.
Females reproduce by laying multiple eggs at once into
a shallow hole that they have dug. The eggs are incubated
by the warmth of the sun or by a layer of rotting vegetation
that the female may place over them.
Tortoises emerge fully formed and independent as they
hatch from their shells. Young tortoises are solitary,
fending for themselves and finding their own food. At
this time, they are vulnerable to attack, and many do
not survive their first few days. Tortoises that survive
continue to be solitary in adult life.
Tortoises tend to have the longest lifespans of all
animals, with some tortoises having lived for over 150
years. The oldest confirmed tortoise lived to be 176
years old, though some reports indicate that tortoises
have lived even longer lives.