Galapagos Islands News

Galapagos is full of dazzling wildlife not found anywhere else: giant tortoises, Darwin's famous finches and mockingbirds, hawks, snakes and more. But ask a biologist, and he or she will tell you that the most impressive native resident is the marine iguana. It's the only lizard in the world that dives underwater to feed, chewing algae off of rocks. It has several unique adaptations to allow it to survive in the islands, including the ability to slow its metabolism to control its body temperature. So what does a marine iguana do in a typical day?

Morning: Galapagos nights can be cool, so marine iguanas tend to sleep piled on top of one another or down in shallow crevasses to preserve body heat. In the morning, they wake up and crawl out of their cracks or off of one another and lie out on the dark volcanic rocks. They have to spend at least a couple of hours in the bright morning sunshine to bring their body temperatures up enough to where their metabolism can function. Smaller iguanas must do this as well as keep an eye on the sky: their natural predator is the Galapagos hawk, and one could swoop down at any minute and grab up a young iguana. Around noon, the iguanas have soaked up enough sunshine and are ready to eat.

Lunchtime! One by one, the iguanas decide they're nice and toasty and it's time for a swim and a snack. They waddle down to the water, not minding if they have to step over one another to do so, and swim out a short distance, using their strong tails to help them swim. Larger, stronger iguanas will swim out further and dive deeper: this has two benefits: it leaves the easy pickings for smaller, weaker iguanas and allows them to eat and grow, and it also means that the stronger iguanas get plenty to eat, as the deeper rocks are gnawed on much less and have more food. The iguanas have special adaptations for this sort of feeding: an element in their blood that allows them to stay under longer and long, sharp, strong claws that allow them to cling to slippery rocks in the crashing surf while they feed. Once they've had their fill of yummy seaweed, they head back to shore.

Afternoon: All of the heat stored up by the iguana in the morning is now gone. Its body temperature may have dropped as much as twenty degrees in the time it spent feeding. It now must spend more time in the bright sun warming up once again to recuperate this lost heat. Along with the seaweed and algae they have eaten, they have also ingested a great deal of salt: this they remove from their system by shooting it out of special glands called supraorbital glands with an audible snort that sounds as if they are sneezing. Once they are warm again, the mature ones may mate if it's mating season, which lasts from December to April. Males fighting over a female or over territory may fight by butting heads with one another: it is rare for a fight to last long or for either iguana to be seriously injured. Females who are ready to lay eggs may spend the afternoon digging holes in the sand where they can lay them.

Night: As dusk falls, the iguanas look for a good place to spend the night. They may look for a small crack in the rocks where they can conserve their own body heat, or they may pile on top of one another in order to share. Some do both: it is not uncommon to see several iguanas packed into a small crack in the rocks. They as night falls they sleep, dreaming of big rocks with lots of algae and not a hawk in sight.