Galápagos tortoises are iconic giant reptiles known for their immense size, longevity, and unique shell shapes. Native to the Galápagos Islands, they have played a crucial role in evolutionary science and conservation.
Galápagos tortoises
Galápagos tortoises (Chelonoidis niger) are the largest living species of tortoise, with males weighing up to 417 kg (919 pounds).
They are native to seven of the Galápagos Islands and can live for over 100 years, making them one of the longest-lived vertebrates.
Their shell shapes vary by subspecies: domed shells are common on humid islands with abundant low vegetation, while saddleback shells with raised necks allow tortoises on arid islands to reach higher plants.
Charles Darwin’s observations of Galápagos tortoises contributed significantly to the development of his theory of evolution.
The Galápagos Islands themselves are named after the Spanish word galápago, meaning tortoise.
A famous tortoise named Harriet lived to an estimated age of 175 years and was cared for at the Australian Zoo.
Male tortoises compete by stretching their necks to appear taller; fights involve biting and nipping when rivals do not concede.
Females lay 2–20 eggs, about the size of billiard balls, which incubate for 4 to 8 months before hatching.
Hatchlings must wait for rainfall to soften the mud cap their mothers place over the nest to dig out safely.
The sex of hatchlings is temperature-dependent: eggs incubated under 28°C tend to be males, those above 29.5°C become females.
The tortoises are ectothermic and spend hours basking in the sun to regulate body temperature before spending long periods grazing.
They can survive without food or water for months, which once made them a convenient source of fresh meat for sailors during long sea voyages.
Several subspecies of Galápagos tortoise have gone extinct due to human impact and introduced species.
Their conservation is ongoing with breeding programs and protections aimed at preventing further decline.
These gentle giants contribute to the Galápagos ecosystem by dispersing seeds and promoting forest growth.
