This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study of shark anatomy suggests the shape of their inner ears is far more variable than expected, and this variation could have more to do with their evolutionary history than where they live or what they eat. The study, published in The Anatomical Record, examined the ears of 10 species of sharks, revealing surprising differences in the shape and structure of an organ that helps them hear and maintain balance.
The research team, led by Cal Poly Humboldt students Kaci Dodd and Isamar Lopez-Argueta and biological sciences professor Allison Bronson, used CT scanning to digitally dissect the heads of 10 species of sharks and examine their inner-ear structures in three dimensions. They studied a wide range of sharks with different habitats, including tiny bioluminescent lantern sharks and deep-sea gulper sharks, the ancient-looking frilled shark, flat ambush predators like the angel shark, and sixgill and sevengill sharks. The researchers expected the inner ears to be shaped by the sharks' ecology, including diet and habitat, similar to what's been found in other groups of vertebrates, Bronson explains.
For example, they wondered whether differences in ear shape might be related to the need to hear certain types of prey or adapt to life at great depths. Instead, they found that sharks with similar diets and habitats had very different ear shapes, so it could be that ear structures are more strongly influenced by evolutionary history. In other words, sharks that are more closely related have similar inner ears, even when they live in different environments.
"The findings are significant because they give us a new way to understand shark evolution and further explore how their sensory system evolved," says Bronson. "This work was possible because we could combine CT technology and a global network of natural history collections." The work required researchers to pore over grayscale CT images for hours, a process Bronson likens to a digital coloring book for adults. Thanks to publicly available specimen data, the Cal Poly Humboldt Fish Collection Database, and collaboration with museums around the world, Bronson's team has been systematically documenting the inner ear anatomy of every living group of sharks and rays.
The lab began this work six years ago, and 15 undergraduates have participated in the project to date. To explore an updated collection of ear models, go to Sketchfab. Kaci Dodd et al, Comparative morphology of the skeletal labyrinth in extant squalomorph sharks, The Anatomical Record (2026).
DOI: 10.1002/ar.70350 BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile → Bachelor's in mathematical biology, Master's in creative writing.
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