Marine Iguanas spend much of their lives sunbathing on the islands’ dark rocky shores. These are the only true marine or sea-going iguanas in the world. They dive into the ocean to feed on algae and can stay underwater for up to forty-five minutes. Sometimes at low tide they can be seen chomping on green algae growing on rocks close to shore. Due to an excess of salt in their diet, while resting and warming up in the sun, marine iguanas periodically sneeze salt from their nose. As cold-blooded reptiles they can’t stay in the cold ocean too long and must climb out of the water and lay on the land to warm up. The marine iguana has a blunt nose, which is well shaped for feeding on algae and a flat tail to propel itself through the water.
The total population of marine iguanas in the archipelago is estimated to be between 200,000 and 300,000. Marine iguanas vary in size, depending on their diet and the islands they inhabit. The largest iguanas are found on the Islands of Fernandina and Isabela where upwelling brings nutrient-rich water to the surface and supports abundant algae growth. They also vary in color depending on their age and location. The young marine iguanas are usually black, while the adults range in combinations of black, green, red, and grey depending on the island. The most colorful iguanas can be found on the shores of Española. Their red and green colors have given them the nickname of the Christmas Iguanas.