“Come here, I need you to help me get this bug off my back.” Photo: Vinesky et al.
Any encounter with a shark is a memorable one, for sure, but for manta rays, it may also carry with it the indignity of being used as a living scrub brush. According to a study published on the preprint server BioRxiv, Galapagos sharks have been observed rubbing up against manta rays to scrape off parasites.
The unexpected behavior was observed in the Revillagigedo Archipelago, located south of the Baja Peninsula in the Pacific Ocean. Researchers captured video footage of three different events in which Galapagos sharks initiated contact with three different oceanic manta rays. They would scrape against the undersides of the rays using their heads, gill regions, and sides – areas where parasites are often found.
“One of the most common ectoparasites found on sharks are copepods. Copepods are small crustaceans that attach to the skin, fins, or gills and feed on mucus and tissue,” lead author Jane Vinesky told BBC Wildlife Magazine. “These organisms are small but mighty. Carrying them in excess can severely impact the health and fitness of the host over time.”
These interactions occurred at or near what are known as “cleaning stations,” meaning areas of the ocean where aquatic life gathers to be cleaned by smaller organisms. The fact that the sharks were resorting to using the manta rays to remove parasites possibly indicates that they are responding to a lack of “cleaner fish,” such as Clarion angelfish, which have seen a decline in population in recent years.
“More sharks may be competing for space at cleaning stations, leading some individuals to seek out less competitive alternatives like mantas,” explained study co-author Mauricio Hoyos to the BBC.
