Bottom contact behavior has been documented with a CATS camera. Screenshots showing a companion whale on its back while sand-rolling (A1) and a companion whale moving its pectoral fin over the substrate from Marker A (A2). Sand-rolling is performed by a companion whale while posting the marker (b) and the tagged individual using its pectoral fin before rolling onto its back from the marker (c). Credit: Olaf Meinecke
A new study by Griffith University finds that humpback whales will use shallow, sandy bay areas to ‘roll’ in sandy substrates to remove dead skin cells on their return trips south to cooler waters.
Marine ecologist Dr. Olaf Meinecke, of Griffith-led Whale and Climate Research Programme and the Center for Coastal and Marine Research used sticky notes to track whales migrating south between August 2021 and October 2022.
The CATS tags are equipped with integrated high definition video, magnesium firing system, VHF loopback transmitter, magnetometers, microphone, light, pressure and temperature sensors, and GPS.
Using data and footage collected from the tags, whales have been observed performing full and lateral rolls in up to 49 meters deep of water on the sea floor lined with fine sand or rubble.
“On all sand-rolling occasions, whales have been observed to move slowly forward with their head first in the sand and then roll to one side or a full roll,” said Dr. Meeneke.
“During the various propagation processes, sand-rolling was observed in the context of socialization. The behavior was either following courtship, competition, or other forms of socialization.
“So we think the whales are molting using sand to help moult and remove ectoparasites like barnacles and specifically identify areas suitable for this behavior.”
In tropical and subtropical waters, barnacles attach themselves to whales in their early life stages, and whales need to remove barnacles frequently to avoid overgrowth that leads to drag and energy loss.
“Humpback whales host diverse communities of skin bacteria that can pose a threat to open wounds if the bacteria grow in large numbers,” said Dr. Meinecke.
“Removal of excess skin is likely a necessity to maintain a healthy skin bacterial community. Humpback whales can remove some barnacles and skin through surface activity such as stomata but not all.”
Whale skin has been observed shedding during the process of all identified coiling, and fish such as juvenile silverfish have been observed actively feeding off whale skin during this behavior similar to cleaning stations which are corals.
The research was published in Whale Peeling – Sand Bottom Contact Behavior of Humpback Whales Marine science and engineering.
more information:
Jan-Olaf Meynecke et al, Exfoliating Whales-Sandy Bottom Contact Behavior of the Humpback Whales, Journal of Marine Science and Engineering (2023). DOI: 10.3390/jmse11030600
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