Humpback whales have been filmed for the first time ever enjoying a ‘spa day’ by rubbing their bodies against the seafloor.

Incredible footage captured in Gold Coast Bay, Queensland, Australia, shows the massive marine mammals performing full and side ‘sand rolls’ up to 50 metres below the ocean surface.

Dr Olaf Meynecke who led the research for Griffith University believes the process was to remove parasites from the whales’ skin which can make them less hydrodynamic.

For the research – published in April 2023 - Marine ecologist Dr Meynecke used suction cup tags to track southward migrating whales between August 2021 and October 2022.

Dr Meynecke said: “We believe that the whales exfoliate using the sand to assist with moulting and removal of ectoparasites, such as barnacles, and specifically select areas suitable for this behaviour.

“On all occasions of sand rolling, the whales were observed on video to be slowly moving forward with their head first into the sand followed by rolling to one side or a full roll.

“During the different deployments, the sand rolling was observed in the context of socialising. The behaviour was either following courtship, competition or other forms of socialising.”

In tropical and subtropical waters, barnacles attach to the whales in their early life stages, but they need to be frequently removed to avoid excessive growth that leads to drag and energy loss.

Dr Meynecke said: “Humpback whales host diverse communities of skin bacteria that can pose a threat for open wounds if bacteria grow in large numbers.

“Removing excess skin is likely a necessity to maintain a healthy bacterial skin community.

"Humpback whales can remove some barnacles and skin through surface activity such as breaches but not all.”

Skin from the whales was observed to be falling off during the process of all identified rolls, and fish such as juvenile silver trevally were seen to be actively feeding from the whales’ skin during this behaviour similar to cleaning stations at coral reefs.

The research Exfoliating Whales–Sandy Bottom Contact Behaviour of Humpback Whales has been published in Marine Science and Engineering.

The research was assisted by Sea World Research and Rescue Foundation and supported by funding to the Whales and Climate Research Program.