14 June 2005

Escher’s sinistral snail

The Dutch artist M. C. Escher (1898-1972) frequently incorporated birds, fishes and insects into his works. In addition, marine mollusks were the sole subjects of two of his drawings (Sea-shell, 1919/1920 and Sea-shells, 1949) and a marine gastropod was depicted on the bottom of the sea in The Fifth Day of the Creation, 19261.

A closer scrutiny of his works revealed three appearances of land snails. The first example, a detail from Castrovalva, 1930, shows a snail shell, perhaps an empty one, on an Italian hillside.

The second example is from Verbum, 1942, where a land snail is crawling in the company of other creatures.

The vast majority of snail shells are dextral (the coiling of the shell is right-handed). This means that when the shell is held with its aperture facing the observer and its apex pointing up, the aperture will be on the right. Nevertheless, there are some genera or even families (for example, the well-known land snail family Clausiliidae) in which the normal shell coiling is left-handed or sinistral.

The two examples above both depict dextral shells. But, Escher’s third land snail, in the lower lefthand corner of Plane Filling II, 1957, is sinistral.

Escher, who was very much into symmetry, was probably keenly aware of the fact that shells can be dextral or sinistral. Note that in Escher's print the sinistral snail's shell fits into the curvature of the fish's tail, while its tentacles fit into the spaces between the turtle's feet. The placement of a dextral snail into the same position, however, would have required the rearrangements of most, if not all, of the other creatures (and the guitar) in the picture. Escher’s sinistral snail was tailored to fit into a “niche” that was created for it in a special universe.

Occasionally, one may chance upon a freak snail specimen in the wild whose shell is coiled in a direction opposite to that of its conspecifics. Such shells are unique finds that offer us clues towards understanding the intricacies of evolution2. Can such individuals fit into the niche of their otherwise oppositely coiled conspecifics and get along just as fine? Or, unlike Escher’s snail, are they misfits in an opposite universe who are doomed to fail in the struggle for life?

1. Locher, J.L. (Ed.). 1971. The World of M. C. Escher. Harry N. Abrams, New York.
2. Örstan, A. & Welter-Schultes, F. 2002. A dextral specimen of Albinaria cretensis (Pulmonata: Clausiliidae). Triton, No. 5, pp. 25-28.

All M.C. Escher works © 2005 The M.C. Escher Company - the Netherlands. All rights reserved. Used by permission. www.mcescher.com

Text Copyright © Aydin Örstan 2005


Henry said...

This reminds me of the human condition, Situs Inversus, in which all the internal organs are in a mirror image position in the body. This is frequently associated with Kartagener syndrome, which involves situs inversus and ciliary dysmotility. The ciliary dysmotility usually expresses itself as chronic sinusitis, chronic lung problems and immotile sperm.


Interesting. I didn't know there was such a condition. Are people with Situs Inversus otherwise healthy if they don't Kartagener syndrome?

Henry said...

In cases of situs inversus totalis, where there is complete reversal of the organs, individuals generally do well, even with the Kartagener's syndrome, as long as the bronchiectasis is treated appropriately. Sometimes there will not be a complete reversal where some organs are switched and some are not, this can cause problems especially when the heart is involved. By the way, Keats' Telescope has a link to some animated tesselations that are pretty neat