How Galapagos Marine Iguanas Helped Darwin Unlock the Secrets of Evolution

April 09, 2012
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When Charles Darwin visited the Galapagos, he was repulsed by the marine iguanas, famously referring to them in his journal as “imps of darkness.” But these “disgusting, clumsy lizards” were one of the keys that helped Darwin unlock the secrets of his theory of evolution. Galapagos marine iguanas are the only aquatic lizards in the world, and Darwin surmised they were able to adapt their ability to swim and dive for food to suit their habitat.

Marine iguanas make their home on the rocky shores of the Galapagos Islands. As such, their limbs and claws are much stronger than those of other large lizards. This allows them to cling to the rocks when waves crash upon them. Their limbs and flattened tails also help them dive into the sea to feed on algae and seaweed. The noses of marine iguanas are also much shorter than those of land-lizards, which helps them get their mouths on rocks to scrape off some algae for dinner with their short, razor sharp teeth. These iguanas typically forage for food in shallow waters, but can dive as deep as 80 feet in search of a snack.

Each sub-species may vary in color, but in general Galapagos marine iguanas are dark gray to black in color, which helps them absorb sunlight to stay warm. This is useful for these cold blooded creatures, as the waters around the islands are typically pretty cold. Larger iguanas are able to retain heat longer and therefore tend to be active for longer stretches. Smaller lizards need to spend more time in the sun to stay warm. When the sun goes down, the marine iguanas retreat underneath large boulders for protection while they sleep.

During mating season, the iguanas' will change color, adopting brassy green and red splashes of color across their bodies. Scientists believe this is associated with eating seaweed that only blooms during the summer months. The correlation of this color change and mating season could either be a coincidence or one may have influenced the other. The mating season of Galapagos marine iguanas lasts for three months each year. Females will lay one to six eggs and then bury them in sand or volcanic ash to incubate for about three months.

While these lizards may not be the most beautiful animals on the Galapagos Islands, they are certainly some of the best-known creatures roaming the archipelago. During daily excursions on your Galapagos cruise, IE’s naturalists will point out both the cute and the not-so-cuddly creatures of this diverse archipelago.


For the latest travel trends and exciting discoveries., visit our Galapagos Islands Travel News section.