How far can marine iguanas swim?

Zoologist Amy MacLeod answers your wild question.


Marine iguanas are an iconic species of the Galápagos Islands © Juan Gabriel Ortiz / Getty


Marine iguanas are found on the Galápagos Islands and feed by grazing on the algae on underwater rocks. The animals are confident swimmers, with powerful legs and a specially flattened tail that enable them to tackle the rough conditions of the Pacific Ocean.

Exactly how far a marine iguana can travel is not known for sure, but these lizards appear able to move between relatively distant islands.

Using genetic data, scientists can determine the island that an individual is from, and have discovered that some have relocated.

Iguanas from Santa Cruz, for example, were found on San Cristobal, more than 65km away. This is surprisingly far, given that the water around the archipelago is rather cold, cooling the lizards and limiting their swimming time.


Other sea-going reptiles, such as saltwater crocodiles, are known to ride oceanic currents – we suspect marine iguanas might be doing the same.