tortoises can live to be over a hundred years old.
The top shell of a tortoise is called the carapace;
the shell that covers a tortoise's belly is called the plastron.
The populations of Galápagos tortoises that live on the hotter
and drier islands of the Galápagos
have developed shells that are saddle-shaped with a high notch above the neck.
This allows them to stretch their necks higher to reach vegetation that grows above the ground.
The Charles Darwin Research Station in the Galápagos raises captive Galápagos tortoises.
This conservation organization reintroduces many tortoises
back into the wild once they've grown big enough that predators don't pose a danger.
The only native natural predator of the Galápagos tortoise is the Galápagos hawk.
The hawk preys on eggs and newly hatched tortoises.
The main threats to adult tortoises are habitat destruction and illegal hunting.
The Galápagos Islands, discovered by Spanish sailors in 1535,
were named after the giant tortoises discovered there.
Galápago means tortoise in Spanish.
Tortoises lay eggs.
Females lay their eggs in nest holes, which they cover and leave.
Babies hatch in four to eight months.
They are on their own from the beginning.
Tortoises are members of the turtle family Testudinidae.
(The term tortoise formerly was used to refer to any land-dwelling turtle.)
About 49 species of tortoise exist.
They are easily recognized by their cylindrical hind limbs and hind feet.
In addition, with the exception of the pancake tortoise (Malacochersus tornieri), the shell is high domed.
Shells of some species are nearly spherical with a flattened base.
Tortoises are exclusively terrestrial and occur on all continents except Australia and Antarctica.
Also, tortoises inhabit many islands,
although numerous island populations and species are now extinct
because of human occupation.
Tortoises live in a variety of habitats, from deserts to wet tropical forests.
Tortoises range in size from the padlopers (Homopus) of southern Africa,
with shell lengths of 4 to 6 inches (10 to 15 centimeters),
to the giant tortoises (Geochelone) of the Aldabra and Galapagos Islands,
with shells over 3.3 feet (1 meter) long.
Most tortoises are vegetarians and eat foliage, flowers, and fruits,
although some tortoise species from moist forest habitats consume animal matter.
Tortoises dig their nests with alternating scooping movements of their hind limbs, like most other turtles.
Most tortoise species lay fewer than 20 eggs, and many small-bodied species lay fewer than 5 eggs.