For many people scuba diving is a passion that draws them into the world of amazing wildlife. You can meet sharks, puffer fish, sea turtles, clownfish, blue tangs, and plenty of other iconic sea creatures at close range. But every now and then you see something that takes you by surprise as it looks as though it could be from another planet.
The Galapagos Islands are most often associated with Charles Darwin, as they were the source of inspiration for his groundbreaking theory of evolution. Located off the coast of Ecuador, they are an archipelago of nineteen islands that are tips of volcanoes that began emerging from the ocean some five million years ago. The limited number of plants and animals that exist there today are said to be descended from castaways that arrived by sea or air.
One of those species is the rather otherworldly looking Galapagos marine iguana. Scientists believe that it descended from South American land-dwelling iguanas that must have drifted out to sea on logs or other debris, eventually landing on the Galapagos.
These unique iguanas are the world’s only marine lizard and can only be found in these islands. At first glance the marine iguanas resembles large lizards with a similar form and scaly skin. But actually they are very different, having developed traits to adapt to their harsh environment. They have evolved blunt noses so that they can graze on seaweed underwater, laterally flattened tails for swimming, and powerful limbs with strong claws to assist in clinging to the volcanic rocks. They also have obelisk-shaped dorsal scales running from the head to the tail.
Fierce-looking but gentle
Their famously unattractive features made even Charles Darwin describe them as “hideous-looking” and “most disgusting, clumsy animals” in his work. Their wide-set eyes, smashed-in faces, punk-like spiky dorsal scales, and knotty salt-encrusted heads makes them look quite menacing, but don’t be fooled. Whereas they look fierce, they are gentle herbivores that survive on underwater algae and seaweed. They are also dark in color (ranging from dark gray to black) to better absorb sunlight after being in the icy Galapagos waters. However, during mating season they have blotches of coppery green and red on their scaled body. They also have special glands that clean their blood of any extra salt that they ingest and razor-like sharp teeth so that they can scrap algae off rocks.
When cornered by an attacker the iguanas actually squirt water at their enemy, which shoots out of their noses. It could be said that this behavior resembles the dragons of fairy tales often described with steam snorting through their nostrils.
Can they survive?
Experts are wondering just how long the marine iguana can survive on the islands, which are becoming increasingly populated by people. Today it is estimated that there are about 250,000 of them distributed on all the islands. They don’t face mammalian predators themselves, but they are under constant pressure from non-native predators such as rats, feral cats, and dogs, which feed on their eggs and young. It is said that humans on the islands are also a big threat, albeit unintentionally. This is because since the marine iguana developed over time in a relatively safe environment, it does not have strong immune systems. This leads to a higher risk of the iguanas’ catching infections to which they are not accustomed. In addition, as their environment didn’t have many natural predators, the marine iguanas have never developed the defenses that are needed to help protect them against new enemies.
Darwin’s theory of the survival of the fittest would seem to suggest that the iguana could be the loser in this battle for life. Today the iguanas are well protected throughout the archipelago and are considered to be threatened with extinction, as their population has been gradually decreasing. Let’s hope that the inhabitants of the Galapagos make sure that these unique and remarkable creatures will not face additional threats so that they can thrive and live peacefully in their beautiful habitat.