Why do fish rub up against sharks? • Earth.com

Why do fish rub up against sharks?

11-07-2021

Today’s Video of the Day from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science explains why fish often take the risk of rubbing up against sharks. The researchers have discovered that this surprising behavior, which is referred to as chafing, is much more widespread than what was expected. 

“While we don’t exactly know why it’s happening, we have a few theories. Shark skin is covered in small tooth-like scales called dermal denticles, which provide a rough sandpaper surface for the chafing fish,” said study co-author Professor Neil Hammerschlag. 

“We suspect that chafing against shark skin might play a vital role in the removal of parasites or other skin irritants, thus improving fish health and fitness.”

Based on the analysis of underwater images, drone videos, and witness reports, the team documented 47 instances of fish rubbing themselves against the skin of a shark. 

Taking place in 13 locations around the world, the chafing events varied in duration from eight seconds to over five minutes. The experts believe that chafing could play an important and underappreciated ecological role for aquatic animals.

“While chafing has been well documented between fish and inanimate objects, such as sand or rocky substrate, this shark-chaffing phenomenon appears to be the only scenario in nature where prey actively seek out and rubs up against a predator,” said study co-lead author Lacey Williams.

Video Credit: Great white and Leerie by Lacey Williams and Alex Anstett Great white and Pacific jack mackerel by Jesus Erick Higuera Rivas Silky shark and rainbow runner by Victor Bach Munoz Whale shark and silky sharks by Jonathan Green

By Chrissy Sexton, Earth.com Staff Writer

News coming your way
The biggest news about our planet delivered to you each day