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notes biology

The Spiral

The Spiral
The snail Littorina angulifera (photo by Alvaro E. Migotto). Cifonauta marine biology image database http://cifonauta.cebimar.usp.br/media/9396/

Here’s a personal view about body symmetry and body openings from someone who lived through the evolution of bilateral symmetry.

Form? I didn’t have any; that is, I didn’t know I had one, or rather I didn’t know you could have one. I grew more or less on all sides, at random; if this is what you call radial symmetry, I suppose I had radial symmetry, but to tell you the truth I never paid any attention to it. Why should I have grown more on one side than on the other? I had no eyes, no head, no part of the body that was different from any other part; now I try to persuade myself that the two holes I had were a mouth and an anus, and that I therefore already had my bilateral symmetry, just like the trilobites and the rest of you, but in my memory I really can’t tell those holes apart, I passed stuff from whatever side I felt like, inside or outside was the same, differences and repugnances came along much later.

Excerpt from The Spiral, a tale in the delightful Cosmicomics collection of science-inspired short stories by Italo Calvino.

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