# Scientists Solve the Mystery of Why Snake Embryos Coil to the Right

*2026-09-02 06:01 UTC · Science · 2 min read*

> A CT-scan study of 900+ embryos reveals that snakes coil right inside the egg because their fast-growing bodies buckle around a tethered gut and left-positioned yolk.

Researchers led by Dr. Tetsuto Miyashita at the Canadian Museum of Nature, with lead author Alexandra Weber of the University of British Columbia, have worked out why snake embryos curl into a distinctive right-handed spiral inside the egg. The team analyzed more than 900 embryos from 39 species of snakes and limbless squamates, combining archival photographs with CT scans to map the hidden anatomy behind the coil.

The answer is mechanical, not genetic. In the first weeks after egg-laying, before the embryo has functional muscles, its body grows faster than its gut, which stays tethered in place. As the lengthening body buckles under that constraint, it twists — and because the yolk consistently sits to the embryo's left, the buckle is pushed to the right, producing the signature right-handed coil. The researchers compare it to tightening one side of a loose strap: the longer, slack side is the one that buckles and twists.

The findings, published in Current Biology, help explain how snakes achieve the longest body plan of any vertebrate: coiling lets a rapidly elongating embryo fit inside a fixed-size egg. Interestingly, the bias fades as hatching nears — once embryos can move on their own, left- and right-coiled individuals become roughly equal in number.

## Sources

- [sciencedaily.com](https://www.sciencedaily.com/releases/2026/09/260901070516.htm)
- [eurekalert.org](https://www.eurekalert.org/news-releases/1141750)

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TechTools News · https://techtools.cz/tools/news/article/2298-scientists-solve-the-mystery-of-why-snake-embryos-coil-to-the-right
Česká verze: https://techtools.cz/tools/news/clanek/2371-vedci-vyresili-zahadu-proc-se-hadi-embrya-staceji-doprava