Early visitors to the Galapagos Islands were far from impressed by the appearance of the marine iguana, a thickset reptile with short but strong limbs and spines along its back and tail.
In 1798, Captain James Colnett of the British Royal Navy called them “small, and of a sooty black, which, if possible, heightens their native ugliness.” A little later, in 1835, Charles Darwin also expressed his revulsion, calling them “disgusting clumsy lizards” and “imps of darkness.”
But this strange creature certainly deserves some respect, if only as an evolutionary phenomenon. Land and marine iguanas likely evolved from a common ancestor that arrived on the Galapagos millions of years ago, probably via natural rafts. Researchers believe they diverged between 4.5 and 8 million years ago, after which the marine iguana developed the ability to forage in the sea. No other lizard that exists today has this ability, making the marine iguana a truly unique creature.
Marine iguanas feed almost exclusively on red and green algae. Females and some smaller males feed only during low tide, staying close to shore and mainly near the surface. But most adult males can dive to depths of almost 100 feet when necessary, and can stay underwater for up to an hour, although most dives only last a few minutes.
At least eight subspecies of marine iguana are recognized, spread across the various islands of the archipelago. Younger iguanas are black in color, but further coloration tends to develop as they age, depending on the island. Adults range from red and black to black and green with some shades of red and grey. The most colorful marine iguanas are found on Española Island, and are often referred to informally as “Christmas iguanas.”
The territory of marine and land iguanas sometimes overlaps, giving rise to unlikely amorous parings. Despite having diverged millions of years ago, the two species can still interbreed. This results in what are known as hybrid iguanas. Hybrid iguanas are very rare, however, and have only been recorded a handful of times on South Plaza, a small island where the two species consistently overlap.
Read more about the Marine Iguana at Galapagos Conservation Trust.
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