Study finds fish rubbing up in opposition to their predators—sharks

While rubbing up in opposition to a shark feels like a dangerous transfer in the event you’re a fish, a collaborative analysis crew led by the University of Miami (UM) Shark Research and Conservation Program on the Rosenstiel School of Marine and Atmospheric Science discovered that this habits is frequent, widespread, and will play a beforehand unappreciated essential ecological function for aquatic animals.

Although cases of fish chaffing in opposition to sharks has beforehand been noticed, this examine finds this cross-species habits to be extra pervasive than beforehand understood. The analysis crew examined underwater pictures, video, drone footage, and witness experiences to search out 47 cases of fish rubbing themselves in opposition to a shark’s pores and skin. The chafing occasions, which have been documented in 13 places around the globe, various in length from eight seconds to over 5 minutes. They recorded 12 fin fish chafing in opposition to eight totally different species of shark, together with nice whites. The crew even documented silky sharks chafing on the top of a whale shark. The variety of fish chafing in opposition to sharks ranged from one to over 100 people at a time. 

“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,” stated UM Rosenstiel School graduate scholar Lacey Williams, who co-led the examine with fellow graduate scholar Alexandra Anstett. 

Using aerial drone surveys in Plettenberg Bay, South Africa, Williams and Anstett documented 25 occurrences of a leervis fish turning to chafe in opposition to a passing great white shark.

“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,” stated UM Rosenstiel School analysis affiliate professor and examine co-author 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.”

The accepted article was printed within the journal Ecology.