A Day in the Life: Marine Iguana

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.

New Iguana Species Discovered in Galapagos

In 1986, rangers hiking on Wolf Volcano on the northern end of Isabela Island noticed several odd-looking Land Iguanas. While most Land Iguanas in Galapagos are a uniform mottled yellow, this one was pink with dark spots and stripes.

The rangers reported the iguanas, but it was assumed for a long time that they were simply regular Galapagos Land Iguanas that had been injured in some way.

Later, a study was initiated to discover if it was a subspecies of Galapagos Land Iguana, with some sort of evolutionary mutation to make it more competitive in its environment. A recent study, however, has scientists and the people of Galapagos buzzing: the pink iguana is a new species, significantly different from the other two Galapagos iguanas.

The announcement, by Gabriele Gentile of Tor Vergata University of Rome (which conducted the study), is a shocker. According to preliminary analysis, the iguana has been on Galapagos for around 5 million years, making it older than many of the islands themselves.

They are only found on Wolf Volcano, which is about 350,000 years old, so they must have moved at one point. The study compared DNA and blood samples taken from 36 specimens since 2001.

There is still much that is unknown about the newest official member of the Galapagos reptile family. Researchers do not know how many there are, what they eat, their mating habits, etc. It is probable that the population is relatively small given their limited habitat, and a breeding program to protect them may be needed.

Northern Isabela Island is home to many dangerous introduced species, such as:

• Cats
• Rats
• Feral goats (which are probably the greatest danger to iguanas because they eat the vegetation).

have been mostly removed from the area. According to current data, the population and risk factors for the pink iguana would classify it as “critically endangered” under the guidelines established by the International Union for Conservation of Nature.

The study shows that the iguanas are not only different in terms of genetics and color, but physically and behaviorally as well. The pink iguana has a more pronounced ridge behind its head and displays a different “head-bob,” a behavior linked to mating and territoriality. The pink iguanas can reach lengths of a little over three feet (one meter) and can weigh up to about 15 pounds (7 kilos).

The Pink Iguana will no doubt take its place alongside other unique and wonderful Galapagos characters, such as the cormorant that does not fly, the penguin that lives on the Equator and the finch that sucks blood.

As Gentile writes in the paper, published in the Proceedings of the National Academy of Sciences: “Despite the attention given to them, the Galapagos have not yet finished offering evolutionary novelties.” This exciting new discovery only reinforces the Galapagos Islands’ nickname: “the laboratory of evolution.”

Land iguana Monitoring on Isabela

Land Iguana’s (Conolophus Subcristatus) census and monitoring has been succesfully accomplished by the Environment Ministry of Ecuador, Galapagos National Park, and Charles Darwin Foundation in southeast area of Isabela Island.

Two hundred and five land iguana were registered and the biometric samples of 86 were taken (body length, tail length and weight) in order to know about their structure and population status.

The outcome of the investigation was positive showing that the iguana population is healthy, growing and now expected to be over 2000 individuals.