Uncovering the Mystery of the Sneezing Galápagos Iguana

On my recent trip to the Galápagos, I could hardly contain my joy at seeing some of the animals that, until then, I had only seen on TV. The marine iguanas were one of my favorites, blending in with the lava rocks, not giving a care in the world about the human activity around them. But I noticed them doing something interesting -- every few minutes, an iguana would let out a big old sneeze, spraying out water up to several feet.

But why are these lava-looking reptiles firing out snot rockets?

To start, it's interesting to note that the marine iguanas, Amblyrhynchus cristatus, are the only lizards in the world to adapt to a marine lifestyle, as they swim out into the ocean to forage on algae.

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Adult marine iguana on Floreana Island.

Due to this feeding behavior at sea, understandably the iguanas ingest not only algae, but also a lot of extra salt (mainly sodium chloride along with some potassium). In order to deal with this excess amount of salt, the marine iguanas have a unique solution. A book on iguana biology summed it up pretty nicely:

To cope with this high-salt diet, the marine iguana uses large cranial salt glands that excrete most of the sodium, potassium, and chloride ingested; forceful expulsion of the secreted fluid is the cause of the dramatic snorting and sneezing observed in these animals.

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Front view of the marine iguana. The flat nose is an adaptation to help them feed on ocean algae growing on rocks.

So it turns out that violent sneezing is actually a pretty clever evolutionary adaptation to dealing with what would otherwise be a fatal salt overload! Not only did we get to see the world's only marine lizards, but I got to learn something new by getting iguana snot sprayed on me.

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Baby Galápagos marine iguana.

Thanks to Destination Ecuador for hosting Jason Goldman and I during our trip throughout several of the Galápagos Islands. I cannot wait to return! I know the iguanas will be right where we left them, blasting out salt water through their schnozes.

Additional reading and sources can be found here, and you can follow for more on my Twitter and Instagram.

See more from Aaron on his YouTube Channel.

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