Tuesday, 15 September 2015

Gustav Tornier and his tortoise, the Pancake Tortoise

Gustav Tornier
Mentioning what would now be regarded as completely crazy ideas of how a dirty environment induced the appearance of fancy goldfish in China and his hypothesis of 'plasma weakness' in my post on Dorothy Sladden and Ernest MacBride, I should note that Gustav Tornier (1859-1938) is best remembered for two things. The first was his incorrect representation of Diplodocus, a sauropod dinosaur, as a crawling, sprawled-leg reptile. The second is Tornier's Tortoise, now usually called the Pancake Tortoise, from rocky areas of East Africa, named after him by Siebenrock in 1903.

Siebenrock named the species Testudo tornieri; it is now Malacochersus tornieri. It was once commonly imported for the specialist reptile collector. Largely now protected, it is now commonly bred in captivity. It lays a single egg at a time—there isn't room for a clutch inside the flattened body.

This is the title page of Siebenrock's paper:

The start of the description of the new species:

The dedication to Tornier:

And the drawing:

And here is the nice short title of the Journal:

It was published in volume 112, pages 439-445.

We wrote about a then new finding in 1973 in an article in the Aquarist and Pondkeeper (38, 237-238):

The Pancake or Soft-shelled Tortoise...must be the oddest of all the land tortoises. The shell, which has the consistency of thick parchment, is thin and flat and entirely lacks a domed carapace. The bony plates which underlie the shell have large apertures so that the whole arrangement gives virtually no protection against predators. Early collectors found that these tortoises are extremely difficult to extricate from the crevices into which they run when disturbed, and suggested that not only do they wedge themselves in but actually inflate the body in order to press the shell against the walls of the crevice.
     In fact the ability to inflate was never checked although the story has been repeated from book to book since the 1920s with greater emphasis on the inflation than on the wedging action of the legs, even though Dr Robert Mertens had failed to find any evidence for inflation during the early 1940s. Drs L.C. Ireland and C. Gans of the State University of New York realised that the respiratory mechanism of tortoises probably would not allow the lungs to be inflated in order to distend the soft shell. Therefore they tested the response of Pancake Tortoises to being forcibly pulled from an artificial crevice they had been allowed to enter. Direct measurements of pressure in the lungs (reported in Animal Behaviour volume 20, pages 778-781, 1972) during this procedure clearly showed that there is no sustained inflation and that the tortoises depend on the wedging action of the fore- and hind-limbs to hold tightly in the crevice...

Later studies have suggested another mechanism. Richard Moll and Michael Klemens (Chelonian Conservation and Biology 1996 2, 26-35) looked at tortoises in the wild and reported that they could expand their bodies. They showed the presence of an extremely flexible diamond-shaped region on the plastron that protrudes when the legs are drawn in. This finding suggests that the lowered plastron region constitutes an important second type of wedge, and one that could easily have been interpreted as inflation of the body with air.

This is a photograph of captive Pancake Tortoises from Wikipedia. I have not been able to find one taken in the wild.

By Dave Pape (Own work) [Public domain], via Wikimedia Commons