Imps of Darkness

“The iguanas are small, and of a sooty black, which, if possible, heightens their native ugliness. Indeed, so disgusting is their appearance, that no one on board could be prevailed upon to take them as food.”

—Captain James Colnett of the British Royal Navy, 1798

Grooved teeth act like rakes. They scrape algae off rocks.

Black scales absorb heat.

Sharp claws help with climbing and holding on to rocks.

A short, square snout makes eating easier.

While the iguana swims, its back spines
balance its body.

Partially webbed feet
help it swim.

Marine iguanas made an impact on some of the islands’ earliest visitors. When naturalist Charles Darwin first saw them, long after Captain Colnett, he found them unappealing, too. He described them as “imps of darkness.”

These are the only lizards in the world that can live and forage at sea. They are endemic to the Galápagos Islands. Scientists believe that they are descended from land iguanas. They probably floated out to the islands from the continent on logs or vegetation.

Salty Sneezes

Marine iguanas swallow saltwater with their food. Then they need to get rid of salt from their systems. Glands in their noses remove salt from their blood. Then they sneeze it out!

Heat‑Seeking Lizard

Marine iguanas can’t control their body temperatures. They rely on a source, like the sun, to do it for them. If you read last month’s edition of Explorer magazine, you’ll know what the word for this is: ectotherm— a cold‑blooded animal.

Marine iguanas will lose an average of 10 degrees of heat in the cold water. So, before they dive in, they try to soak up enough heat to raise their body temperatures.