Philip Hoare
Thu, 6 July 2023
Grey whales have learned to approach whale-watching boats to have parasites removed by human beings, it has been claimed.
Video footage documenting the behaviour in the Ojo de Liebre lagoon, off the coast of Baja California, Mexico, shows a grey whale having whale lice picked off its head by the captain of a small boat. “I have done it repeatedly with the same whale and others,” Paco Jimenez Franco told a US news site. “It is very exciting for me.”
Whale lice or cyamids – pale, crab-like creatures that crawl about on the animal’s heads – can be beneficial for whales, eating algae on their bodies and feeding on flaking skin and the sites of wounds. However, it is assumed that they also irritate the animal.
“I think the grey whales have a love-hate relationship with their whale lice,” said Mark Carwardine, a British zoologist with wide experience in the region. “They have very sensitive skin, and thousands of these little creatures holding on tight, or moving about, with their exceedingly sharp, recurved claws, must drive them nuts.”
He added: “It can actually hurt when a whale louse grabs hold of your finger – it feels like tiny pinpricks.”
Franco picked a louse off the head of the whale the first time it came close enough for him to do so. “Once I removed the first one, she approached again so that I could continue,” he said. The same individual whale has returned repeatedly for more “grooming”, according to Franco.
Like many of the relatively slow-moving great whales, including humpbacks and right whales, grey whales – which can grow up to 15 metres (50ft) in length – are particularly susceptible to parasites. They also acquire barnacles as they graze on minute amphipods at the silty bottom of the sea.
The grey whales off Baja California are celebrated for their inquisitive behaviour towards boats, even though they were hunted drastically in the 20th century. They were known to whalers as “devil fish” on account of their ferocity in fighting back against hunters, whose tactics included killing a nursing female’s calf to ensure the adult came close enough to be harpooned. The whale’s only other predator is the orca.
While he could not confirm that approaching humans for delousing help constituted new behaviour in whales, Carwardine said he had not seen it before. “The whales certainly don’t seem to mind when people pick them off, although you’d have to pick off hundreds to make much of a difference,” he said.
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Because the lice eat sloughed whale skin and damaged tissue, he noted that “rather than parasites, they are really what we call symbionts – in other words, each animal benefits from the other”.
The new grooming behaviour could be considered similarly symbiotic. Given that grey whales can live for at least 80 years, it is possible that animals that were alive during the period of hunting have since adapted to benefit from interaction with humans.
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