If you’re planning a luxury Galapagos cruise, you’re almost certainly doing so because you have an interest in the plants and animals of the islands, and in particular their association with Charles Darwin’s theory of evolution. It goes without saying, then, that you’ll want to know a bit about the animals you’ll encounter on your once-in-a-lifetime luxury Galapagos cruise. This first blog in the series takes a look at the emblematic Galapagos tortoises.
The Galapagos Islands may be home to myriad weird and wonderful endemic species, but none represents them more adeptly than the giant Galapagos tortoise. The islands are named after the tortoises (the old Spanish word galápago referred either to their saddle-shaped shells or just to the tortoises themselves, depending on who you believe) and the variations between the populations on different islands were responsible for planting the seed of evolution in Darwin’s mind.
Believe it or not the tortoises actually swam the 1000 km (or at least were borne by the strong Humboldt current – they are very weak swimmers) from mainland South America. Although they resemble giant Indian Ocean tortoises, their closest genetic relative is the Argentine or Chaco tortoise – a much smaller species. Their first ports of call are presumed to have been Española and San Cristóbal (the oldest islands) from whence they went on to populate the other islands in a stepping-stone fashion.
Weighing in at an average of 250 pounds, the largest recorded specimens have attained weights of 475 pounds. This makes them the largest tortoise species on the planet and the tenth heaviest reptile in the world. They are also one of the longest-lived species – most tortoises in the wild die at about 100 years, but one captive specimen reached at least 170 years of age. The tortoises are herbivorous and they eat as much as 80 lb of vegetation in a single day.
What’s so amazing about the tortoises is that the populations on different islands (and even in different parts of different islands) vary genetically. Although there were once as many as 15 subspecies (this figure is disputed) now only 10 remain. Subspecies occur on the following islands:
The subspecies can be divided into two distinct shell shapes: domed and saddleback. In domed tortoises, the front edge of the shell comes right down to the neck while in saddle-backed tortoises the front of the shell arches high over the neck. Domed tortoises live in moist highlands and eat grasses and low-lying shrubs. Saddle-backed tortoises, on the other hand, live in arid regions and feed on taller plants. The arched shell allows them to stretch their heads much higher than their domed cousins.
Historically the tortoises were prized for their meat by sailors – their size means one individual can feed many mouths, and the fact that they are able to survive for 18 months without water was priceless in the pre-refrigeration age. What’s more they are very rich in oil, and this was extracted and burnt in the lamps of Quito. In total about 200 000 tortoises were killed before the 20th century, and their total population reached an all time low of around 3000 in the 1970s.
Since then, things have got a lot better. In 1965 the Charles Darwin Foundation began captive breeding programs, while in 1970 it became illegal to capture, remove, or kill the tortoises or their eggs. The Galápagos National Park Service has also undertaken extensive island restoration projects, with the ultimate goal of returning the islands to their pre-human condition. All these efforts combined have seen the total population grow to an estimated 20 000 individuals and there are even hopes of selectively rebreeding some of the extinct species.
In spite of all of this, the Galapagos tortoise remains a critically endangered species. But at least it is a species which you – and hopefully your grandchildren – will be able to see on your luxury Galapagos cruise.