by Greg Mayer

Matthew sent me and Jerry this Tweet from PADI, of a wonderful video clip by Turtle & Ray Productions in Curaçao. It reminded Matthew of mosasaurs, an extinct group of giant marine lizards from the Mesozoic.

It's not everyday you spot a land iguana roaming the reef in Curaçao 🦎. 🎥 : IG user turtleandray_photography pic.twitter.com/RzoNE5fZJ3

— PADI (@PADI) April 1, 2019

The common green iguana (Iguana iguana iguana) is widespread in Central and South America, and has also been introduced to a number of other places, including South Florida, where it is flourishing. It’s long been known that they readily take to water, both fresh and salt. I saw and photographed one in the harbor at Charlotte Amalie on St. Thomas in the Virgin Islands, but I’ve never gotten to see one from an underwater perspective! My friend and colleague James D. “Skip” Lazell, Jr., published this field sketch he made of a swimming iguana in his monograph on the genus Iguana in the West Indies. (This is Iguana delicatissima, a species endemic to the northern Lesser Antilles).

I immediately thought of the marine iguana, Amblyrhynchus cristatus, endemic to the Galapagos, where it lives along the coasts, and feeds on algae in the sea. Like the green iguana, in person I have only seen them from above the water. The following video, from Scuba Hank NYC, shows them underwater, both swimming and feeding. Upon seeing these lovely beasts lining the shores of the Galapagos, Darwin is said to have leaned over the the bow rail of the Beagle and exclaimed, “Wow, lizard city!”

In looking for an appropriate marine iguana video, I came across this intriguing video, of a kayaker rescuing a green iguana four miles at sea off the Florida Keys. Besides being a wonderful story, and a testament to the kayaker’s humanity and, the iguana’s tenacity and ingenuity in figuring out that staying with the boat and jumping on, despite the presence of a man, was a good move, it helps to show how iguanas may have gotten to the Galapagos: they readily enter into, and can survive for some time, in the sea. Though not capable of directed swimming over great distances, this would make it more likely than landlubbing lizards that they could be carried off to a distant landfall, by what Darwin called “occasional means of transport.”

Lazell, J.D. 1973. The lizard genus Iguana in the Lesser Antilles. Bulletin of the Museum of Comparative Zoology 145:1-28. BHL

Neill, W.T. 1958. The occurrence of amphibians and reptiles in saltwater areas, and a bibliography. Bulletin of Marine Science of the Gulf and Caribbean 8:1-97. pdf