The metaphorical ink had hardly dried on my post (22 March 2019) about salt glands in Galapagos Marine and Land Iguanas and their hybrids when my attention was drawn to a recent video of a common South and Central American iguana, the Green or Linnean Iguana (I. iguana), swimming along a reef off Curaçao.
It's not everyday you spot a land iguana roaming the reef in Curaçao 🦎. 🎥 : IG user turtleandray_photography pic.twitter.com/RzoNE5fZJ3— PADI (@PADI) 1 April 2019
The question raised, of course, is: was it was feeding on the reef. I am sure that iguanas could swim for hours in sea water without taking in any sodium chloride but eating is a different matter since, like the Galapagos Marine Iguana it is difficult to see how ingestion of sea water could be avoided.
Fundamental questions about the salt gland of a number of iguanid lizards, which appear to be able to swap between a high sodium to a high potassium secretion according to diet or salinity of water ingested, remain unanswered. Some of the questions may be basic, for example, do high sodium and high potassium secretions come from the same gland in the head, or the same cells of one gland? We need some proper physiology and cell biology to find out. And more observations from divers of the type shown in the video.
For more information on the sighting of iguanas in the sea, see Greg Mayer’s post on Jerry Coyne’s WEIT here.
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