EDGE Species Spotlight

Marine Iguana

Names: Marine Iguana OR Saltwater Iguana (Amblyrhynchus cristatus)

Size: These dark grey lizards with spikes can grow 4 to 5 feet. At 1 to 3 kilograms they’re relatively light, weighing roughly the same as a big pineapple or a laptop.

Favourite hangout: Sunbathing on a rock to get warm after foraging in the sea around the Galapagos, their forever island home


Favourite Snack: Red and green algae, which they scrape off rocks and dive for in the ocean – it’s the only lizard in the world that swims for its food.

Love language: Land is where these sea lizards get lovey-dovey. Like male species the world over, male marine iguanas want attention when they feel the urge. Colour is the big thing for these dudes, with some becoming more intensely red, green, grey, or black when Cupid holds sway. They males fight it out with other vibrant guys for the rights to quality time with the ladies.

If you see them: With their dorsal spikes, fierce faces, and pale heads, these salty lizards can appear aesthetically challenged. Charles Darwin thought so when he encountered them in 1835, calling them ‘hideous looking’! But even the mastermind of evolution had to admit they were elegant swimmers, and there’s something to be said for physical grace.

Pet peeves: El Niño temperature fluctuations, which warm sea water and kill off their beloved red and green algae. The brown algae that replace them are no substitute and may even be toxic to these critters, who can lose 10-90% of their mates in bad years. Hungry hawks and herons are also a worry, as are non-native cats, and dogs.

Learn more about the Marine Iguana

Growth: Most species get bigger as they mature, but marine iguanas shrink, too. When food is scarce, these critters lose weight, and their bodies shorten by up to 20% in their bid to survive. The smaller they are, the less energy they use to forage, the better their chance of pulling through. When the water cools and food is plentiful again, they regrow – a cycle that repeats throughout their 12- to 60-year lives. But it’s left some wondering: can these unique lizards actually digest their own bone?!

Facts: Landloving ancestors of Galapagos marine iguanas are believed to have drifted over on debris from South America millions of years ago. There are 11 sub-species, all with a special gland near their nostrils to help their bodies remove salt swallowed while feeding. This salt is ‘sneezed’ over their heads, giving them the grey-white air of elder statespeople!

Personality type? The Sizeshifter. The loud sneezer. 

How at risk is it? Vulnerable (VU).


We sent a photographer and two surfers to the Galapagos to explore their connections with nature.