Scientists discover why snake embryos twist into spirals

Snake embryos begin life curled into a distinctive right-handed spiral, and scientists may finally know why. Their bodies grow faster than their guts, creating a tether that forces the lengthening embryo to buckle and twist inside the egg. Researchers reached the conclusion after studying more than 900 embryos and using CT scans to reveal the hidden anatomy behind the coils.

Scientists discover why snake embryos twist into spirals. This coiling behavior appears to help snakes accommodate the exceptionally long bodies that distinguish them from every other vertebrate. The findings, published in Current Biology, suggest that the spiral forms as the embryo’s body rapidly lengthens while its gut acts as a tether.

That physical constraint causes the growing body to buckle and twist into a right-handed coil. "It’s like when you adjust the length of a strap and the longer, buckling side of the loop twists," explains senior author and team leader Dr. Tetsuto Miyashita, evolutionary biologist at the Canadian Museum of Nature.