Whale sharks found to slow down to allow researchers to scrape off parasites

Three marine scientists from The University of Western Australia discovered that certain whale sharks may slow down when researchers ask them to gather copepods from delicate regions by hand-scraping. Brendon Osorio, Grzegorz Skrzypek, and Mark Meekan observed in their study, which was published in the journal Fishes, that whale sharks have grown more cooperative in recent years when scientists have tried to obtain parasite samples from them.

Whale shark skin and/or parasite samples have long been collected by marine biologists. The sharks are the biggest known living fish and the largest vertebrate that is not a mammal. They are sharks, not whales, and their vast size—the biggest verified size is 18.8 meters in length—is how they received their moniker. Since the sharks are filter feeders, there is minimal chance that they will bite. However, due to their size, approaching creatures run the chance of being hurt. They are investigated by scientists to understand more about them and the ocean habitat in which they reside.

For almost a decade, scientists have been researching sharks and gathering skin and tissue samples to understand more about what the sharks may be consuming and how deep they may dive. In more recent years, scientists discovered that collecting copepods, a type of microscopic parasitic crustacean that adheres to the sharks' skin, allowed them to obtain nearly the same data. They also observed that suckerfish, which attach to sharks, do so in order to consume copepods, however they typically only clean copepods from flat, accessible areas of the skin. The copepods that are attached to the regions near the mouth and fins are unharmed. The researchers started focusing on specific regions using a tiny plastic knife to remove and bag the parasites.

As time went on, the researchers repeatedly collected samples from the same shark, and the sharks appeared to enjoy the interactions as they began to slow down and, in some cases, stop swimming when the researchers approached, making the researchers' work easier. They contend that getting rid of the parasites lessens discomfort and improves swimming performance.