All sharks obey the same hidden geometric rule, study reveals

A new study has uncovered a striking pattern in shark biology: despite their vast differences in size and shape, all sharks follow the same geometric rule. Researchers examined 54 species, from tiny lanternsharks to enormous whale sharks, and found they obey the 2/3 scaling law almost perfectly. This rule predicts how surface area and volume change as an organism grows larger. The research was led by Joel Harrison Gayford, a PhD candidate at James Cook University. His team analysed sharks of wildly different sizes—some small enough to fit in a hand, others as long as a city bus. Even after accounting for factors like ancestry, lifestyle, and life stage, the sharks showed only minor deviations from the 2/3 law.

The study suggests that breaking from this geometric rule would come at too high an energetic cost for sharks. Their findings imply that evolution has constrained shark bodies to follow this mathematical pattern, regardless of their environment or behaviour. Beyond sharks, the research could have wider applications. It may help refine conservation models or inspire the design of underwater vehicles and robotic swimmers. The team also sees potential for similar investigations across other animal groups.

The discovery confirms that sharks, despite their diversity, adhere to a fundamental biological principle. This consistency could now shape future studies in marine biology and engineering. The findings also highlight how geometric rules govern life, even in creatures as varied as sharks.