Gray whales have been sighted swimming alongside boats, allowing humans to dislodge the parasites from their heads.
Remarkable footage has captured the fascinating interaction off the west coast of Mexico, about 385 miles south of California, USA.
Whale Watching Captain Paco Jimenez Franco has spent the last 20 years spotting the incredible creatures at Ojo de Liebre, a lagoon on the Pacific coast of the Baja Peninsula.
And recently he was filmed removing lice from a whale that was grazing along the side of his small tourist boat.
He told US news outlet The Dodo: “After I removed the first one, it came back to me so I could proceed with it.”
“I’ve done it repeatedly, with the same whale and with others. It’s very exciting for me.”
The lice – also called cyanide amphipods – are tiny crustaceans that live on the rough patches of whale skin and eat algae.
It is not certain if they are harmful to whales. However, some researchers believe they may be of use.
But Franco thinks the fact that the whales have kept coming back to take off gives them some relief — an idea some experts agree with, given that the cyamids are likely to be irritating.
He said the same whale repeatedly approached his boat to “groom” him even more and that she lifted her head out of the sea and stayed there long enough for him to remove many lice.
Franco added, “The whales certainly don’t seem to mind if humans kill them, although it would take hundreds to make a big difference.”
Tourist Jerome Evangelio, who shared the video on Facebook, said the whale voluntarily approached the boat.
The post states, “The trust between the gray whales and boat captains in the Calf Lagoon of Ojo de Liebre in Guerrero Negro is something that has developed through numerous encounters over the years.”
“This whale didn’t object to our captain Paco removing whale lice from his head.”
“Thank you Jordan Lightner for capturing this incredible moment during our adventure.”
Veteran British zoologist Mark Cawardine said he believes gray whales have a “love-hate relationship with their whale lice.”
He told The Guardian: “They have very sensitive skin and thousands of these little creatures holding on or running about with their exceedingly sharp, curved claws must be driving them insane.”
Franco said his lice-collecting exercise began when a whale came very close to his boat, and he suspected it was asking for help removing the crustaceans.
Since then, the same whale and others have continued to return, which only further underscores his appreciation for their amazing nature.
He added, “By observing their behavior, I’ve learned that there’s a certain nobility in them. They’re amazing.”
Whale touching is largely banned around the world, but is permitted in certain regions along the Baja California coast if the whale initiates the interaction.
Gray whales can grow up to 50 feet long and weigh up to 41 tons while they generally live between 55 and 70 years, although they have been known to live up to 80 years.
Orcas – another species of whale – have recently rammed boats across Europe, including in British waters.
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