Galapagos Sharks Use Manta Rays as Living Scratching Posts

Recent observations off Mexico’s Revillagigedo archipelago have revealed a fascinating behavioral adaptation among Galapagos sharks: they are utilizing manta rays as makeshift scratching posts. Researchers documented sharks rubbing their snouts and gills against the rough, sandpaper-like skin of manta rays to dislodge parasites. This behavior, observed on eight separate occasions, suggests that sharks have developed creative, opportunistic methods to manage skin irritation when traditional "cleaning stations"—areas where smaller fish typically remove parasites—are unavailable or overcrowded.

The interaction appears to be largely non-hostile, though the manta rays' reactions vary based on the size of the shark. While mantas seem to tolerate juvenile sharks, they actively flee from larger adults, likely due to the perceived threat of a bite. Marine biologists note that the rough texture of the manta’s skin, composed of tooth-like dermal denticles, makes them an ideal surface for exfoliation. This discovery highlights the complex, often overlooked social and ecological interactions occurring between large marine species.

This behavior provides valuable insight into the adaptive intelligence of sharks. Rather than relying solely on symbiotic relationships with cleaner fish, sharks are demonstrating trial-and-error problem solving to address their physiological needs. As competition for resources at traditional cleaning stations increases, these alternative strategies may become more prevalent. This study underscores the importance of protecting diverse marine ecosystems, as the health of one species—like the manta ray—can play an unexpected role in the hygiene and well-being of another, such as the Galapagos shark.