The Galapagos aren’t your average tropical archipelago; instead they’re a menagerie of animals weird and wonderful, big and small, terrestrial and marine. Perhaps no creature is more ubiquitous, more creepy and more undoubtedly Galapagosian than the marine iguana.
On your luxury Galapagos cruise you’ll be sure to see hundreds if not thousands of them, and it’s quite likely that – like Darwin – you will view them as “large, disgusting, clumsy lizards”. This would be a pity, however, as they are fascinating creatures which are unique in many ways.
What makes them so special?
How did they get there?
They are thought to have on ‘rafts’ of floating vegetation from mainland Ecuador or Peru. It is believed that the Galapagos land and marine iguanas share a common ancestor, and that the two different species evolved once already on the archipelago – albeit on older islands which are now submerged by the ocean.
What do they look like?
Marine iguanas vary in color from black to gray (dark colors aid heat absorption), while during breeding season males take on red and green tinges caused by the type of algae which is dominant in their diet.
The males are bigger than the females, but the size of different subspecies varies wildly. The smallest specimens measure 20 inches and weigh 1 lb, while the largest can weigh as much as 22 lb and measure five-and-a-half feet in length!
When compared with Galapagos land iguanas, the marine variety is smaller and possesses a shorter snout (for feeding on algae) a longer flattened tail (for more effective swimming) and long curved claws for clinging onto rocks in strong currents.
As with many Galapagos species, different subspecies of marine iguana occur on different islands. There are six subspecies which vary greatly in size. The largest occur on Isabela and Fernandina Islands and the smallest are found on Genovesa.
Another major difference between the subspecies is the color changes undergone by males during breeding season:
Diet and behavior
Marine iguanas evolved so as to be able to feed on the algae that live in tidal and intertidal zones. Although they are famed for their diving abilities, about 95% of feeding actually takes places in the intertidal zones which are exposed during low tide.
They are extremely graceful and agile in water, but they do get very cold when doing so. After a lengthy swim they have to bask in the sun for a considerable period to warm up.
Breeding takes place – depending on the island – somewhere between November and January. During this season, males starve themselves and partake in fights over the prime breeding territories.
Once mating has taken place, females lay their eggs in complex burrows and guard them from sabotage by rival females. Incubation takes about 95 days, with thousands hatching at the same time. This gives them a greater chance of survival, as the hatchlings are extremely popular snakes, hawks, gulls and owls as well as feral dogs and cats.
Want to know more?
Unfortunately space constraints only allowed me to scratch the surface of what is known about this fascinating species. If you want to find out more, an insightful article by an evolutionary biologist who spent 6 months studying iguanas of Santa Fe Island can be found here.
By far the best thing to do, however, is to book a luxury Galapagos cruise with Vaya Adventures and see the marine iguanas for yourself. They occupy virtually every rocky stretch of coastline in the Galapagos, so you’re guaranteed to see them. That way you can make up your own mind about Darwin’s opinion of these “hideous-looking creatures.”