Wednesday, 19 November 2014

Salt Glands in Iguana iguana. Somebody got there first

After Knut Schmidt-Nielsen described his discovery of salt glands in marine birds in 1957, other scientists and naturalists realised that they had seen the phenomenon earlier but had no appreciated what they were seeing. In the early 1960s, salt glands were discovered in terrestrial lizards (the salt gland in the Galapagos Marine Iguana was described by Schmidt-Nielsen and his friend Ragnar Fänge in 1958).

In 1963 Knut, with Arieh Borut, Ping Lee and Eugene Crawford in a paper in Science (142, 1300) reported:

A specimen of the tropical lizard Iguana iguana which was kept in the laboratory was occasionally found with white incrustations around the nostrils. The material was water soluble and preliminary analysis showed large amounts of potassium as well as sodium. Closer observation of the lizard while kept in a glass-walled terrarium revealed that the animal had the habit of pushing its nose against the wall thereby leaving a salt deposit on the glass.

A few weeks ago I was looking for information on Mrs Kathleen Pickard Smith for my other blog on the history of keeping reptiles and amphibians. She wrote a popular book on her experiences during the 1950s, Living with Reptiles, which was published by Thomas Nelson & Sons of Edinburgh in 1961. I read the book in 1962 and eventually gave it to the Zoo library. On reading bits again while I was scanning it,  I find she noted the following about her iguana, 'Ig':

Never a fast or a hunger strike to alarm us—true, he sneezes quite a bit in cooler weather, which leaves a chalky deposit on his nostrils and on the glass of his cage, but this is quite natural.

So, again we have an observation of salt glands in action, this time in a terrestrial lizard, before the observer could appreciate what had been observed.