There is only one kind of lizard in this world who traverses both land and sea…and you’re lookin’ at it. This is the loveable face of the marine iguana, Amblyrhynchus cirstatu. They live only on the Galapagos Islands, an archipelago in the Pacific Ocean about 500 miles west of Ecuador.
Without the need for shelter, shade, or fresh water, marine iguanas live solely by the cycles of the sun and moon. They rely on the sun to heat their bodies and the moon’s tides to feed their bodies. Their dark black skin is designed to fully absorb the sun’s rays, so you see large groups of them lying motionless, bunched up together in the chilly early morning light, while they gather heat for their daily adventure. Living on the equator, the sun soon greets them and heats them, and then they can move. The sight of dozens and dozens, sometimes hundreds of these 2-4 foot long iguanas basking on the rocks and lava is so surreal it is almost unbelievable.
Although the islands are equatorial, the overall climate is not necessarily tropical. Located at the intersection of three main ocean currents, some of which originate in Antarctica, the islands’ surrounding water is cold. But it’s nutrient-rich. After they’ve warmed up, the marine iguanas saunter across the hot, rocky lava, their long reptilian tails dragging behind, and they gather along the shorelines to eat. Their long spooky claws are handy for clinging to the rocky surface of the lava.
With a diet of primarily marine algae and seaweed, some iguanas advance beyond the shore and into the water’s depths. The bigger bodied iguanas, like the males, hurl themselves into the water to eat seaweed on the ocean floor and shallow reefs. There is a risk to entering the cold water, for their body temperatures drop fairly quickly rendering them dangerously immobile if they get too cold. Therefore, they’re only in the water for 5 or 10 minutes. The smaller-bodied females and the young stay on land for this reason.
The islands are so far off into the ocean that most of the animal inhabitants are unaccustomed to predators. This is what makes the Galapagos a place of strange sights and unusual experiences. You can get fairly close to these animals because they don’t know the danger of man. But getting close to a marine iguana is not a cozy experience. When they feed, they take in salty sea water; and special glands in their nostrils filter out the salt. The result is water shooting out their nostrils. Not the most charming creatures on this planet.
Marine iguanas don’t all look the same. Some have algae on their short snouts, some have white crystallized sea salt that has accumulated there. Sometimes their bodies temporarily shorten if there is a food hardship (like during El Nino weather patterns). Also, during breeding season and in conjunction with a red pigment in seaweed that blooms in summer, some of the iguanas are bright red and green.
Fortunately, marine iguanas are a protected species. There are a few natural predators like hawks and owls that prey on the young. More troublesome, however, is the growing population of feral cats and dogs. Oil spills polluting their water can also be a problem. At present their conservation status is rated as vulnerable. Estimates of the total population vary and fluctuate, but the count seems to be about 200,000 to 300,000.
One of my fondest memories in the Galapagos—and I have many—is the day we happened to snorkel with marine iguanas. The water was cold and we were in shallow water, rocked about by the forceful waves, looking for fish. At the ocean floor a few feet away we spotted one, then another marine iguana underwater with us. I stared at that crazy sight as long as I could: a large lizard completely submerged underwater, grazing away on the algae. I knew I might never again be eye-to-eye with a lizard underwater…and I was right.