A new genomic study is challenging one of the most familiar labels in marine biology: the shark.
Scientists analyzing the genomes of dozens of ocean predators have discovered that animals commonly grouped together as “sharks” may not form a single, unified evolutionary group.
Instead, the research suggests that several species traditionally called sharks are more distantly related than previously believed, shaking up the long-standing family tree of these iconic marine hunters.
For centuries, sharks have been classified based largely on physical traits such as body shape, gill slits, and skeletal structure made of cartilage.
These characteristics seemed to place them neatly into a single branch of the evolutionary tree. But modern genetic tools are revealing a more complicated story.
Using advanced genome sequencing, researchers compared large sections of DNA across numerous species of sharks, rays, and other cartilaginous fish.
Their analysis found that some animals commonly labeled as sharks share closer genetic ties with rays and skates than with other shark species.
This means the term “shark” may be more of a convenient description than a precise scientific category. In evolutionary terms, it may not represent a single lineage descending from one common ancestor.
Instead, the study suggests that the group known as sharks may consist of multiple evolutionary branches that split apart far earlier than scientists once believed.
The findings could reshape how scientists understand the evolution of cartilaginous fish, a group that has existed in Earth’s oceans for more than 400 million years.
Researchers say the new genomic data may also help clarify how different species adapted to a wide range of marine environments—from deep ocean waters to coastal ecosystems.
Beyond revising textbooks, the discovery could have practical implications for conservation. A clearer understanding of evolutionary relationships can help scientists identify which species are most unique genetically and may therefore require greater protection.
Despite the scientific shake-up, researchers say the word “shark” is unlikely to disappear from everyday language anytime soon. But the study serves as a reminder that even the ocean’s most familiar predators can still hold evolutionary surprises hidden within their DNA.
By Mary Munywoki
