For many of us the colours red and green trigger memories of Christmas. Glossy holly leaves and berries, a beautifully decorated tree, Santa in his red suit, a pile of wrapped presents.

But a questionably ugly reptile? Probably not – and yet …

One of the creatures I found most intriguing in the Galápagos Islands was the marine iguana, although not everyone has been as enamoured of them as I was:

The black lava rocks on the beach are frequented by large most disgusting, clumsy lizards. They are as black as the porous rocks over which they crawl & seek their prey from the sea. Somebody calls them ‘imps of darkness’. They assuredly well-become the land they inhabit.

Charles Darwin, 1835

These fascinating creatures are endemic to the islands. All the marine and land iguana species in the Galápagos are thought to be descendants of a single species, the green iguana, which is native on the South American continent. Arriving probably on vegetation rafts to the isles, the green iguanas, in order to survive, had to adapt to a new and different environment by evolving into two very distinct new species. One of these, the land iguana, adapted to feed on the vegetation of the islands.

But some of the green iguanas found themselves on islands where vegetation was sparse. These turned, through necessity, to the plant-life beneath the sea, and thus became the world’s only sea-going lizard. They have developed a flattened snout and sharp teeth in order to feed on the algae on the underwater rocks. Their tail is flattened vertically like a rudder to help them swim and they have long claws to grip the rocks while feeding so that they don’t drift away.

So why ‘Christmas’?

There are seven sub-species of marine iguanas, varying in size and colour. Each is unique to a single island (or in a couple of examples, to two islands). Most are black or dark grey, but some have red colouring too, most notably on Española. Here the males have not only red but often green colouring too, which becomes brighter during the mating season, giving them the nickname of ‘Christmas’ iguanas.

Marine iguanas can stay submerged for up to ten minutes, before having to come up for air. When not feeding they are usually found sunning themselves on lava rocks, often in large groups and, as we saw in several places, even piled up on top of one another! Sometimes you will see them appear to sneeze; in fact they are snorting to get rid of any excess sea salt with the help of special glands in their nostrils. The only place I managed to capture this behaviour on video was on Santiago Island; you’ll note the different, duller, colouring in this very brief clip.

In addition to their brighter colours, the marine iguanas on Española were also among the largest we saw. They were more active than many; this little video shows their distinctive walk and the line they make with their tail in the sand. Watch how his back leg almost touches the front one; in fact, it was here on Española that I saw one iguana nearly fall over his own feet, as the back foot landed on top of and got tangled with the front!

I hope you’ll find these bizarre animals as intriguing as I do, and see them as a fitting contribution to the Friendly Friday ‘Red and Green’ theme. And if you’ve enjoyed this encounter with the Christmas iguanas of Española you might also like to meet some of the other residents of the island, the Waved Albatross.

_{I visited the Galápagos Islands in 2012}