G-day, mate! Up for some seaweed footy?

Meynecke, J.-O.; Kela, H. What’s at Play: Humpback Whale Interaction with Seaweed Is a Global Phenomenon. J. Mar. Sci. Eng. 2023, 11, 1802. jmse11091802

Whales and dolphins are known to be extremely intelligent, not only demonstrating tool use, self-awareness, but also social engagement. All these skills are steadily acquired from birth onwards, on grounds of a very strong mother and calf bond, to ensure survival in an ever-changing environment.

This study has recorded many incidences were humpback whales (Megaptera novaeangliae) and other baleen whales have become cognitively engaged with floating kelp and seaweed patches off the coast of North America and Australia.

In the past humpback whales have rarely been spotted in the act of performing tool use or engaging with any foreign objects, but with social media platforms speeding up and various people posting their whale experiences with the rest of the world, this has become a very valuable source of information to mammalogists to complement their scientific research.

Tool use in animals is defined as the act of using any kind of tool to achieve a higher goal, as to acquire food or water, for grooming, combat, defence, communication, play, or construction. Regarding playful behaviour in animals, no clear definition has been put forth to explain what “play” needs to look like and is therefore very much debated.

Nevertheless, many mammalogists have described dolphins and whales playing. In the wild, dolphins have been spotted engaging with sponges, seaweed, shells, and marine debris, describing this behaviour as playful, consequently reinforcing social interactions to optimise hunting techniques. Dolphins in the Red Sea also rub their rostrums against corals and sponges to treat or prevent microbial infections.

In Australia and North America “kelping” or “kelping play” shows whales rubbing and rolling their body against seaweed, which scientists suspect to be either “playing”, stimulating sensory hairs attached along the jaws and head, “doctoring” skin infections or socialising.

To clarify, why whales interact with seaweed Dr Meynecke and his colleagues carefully searched through Facebook, Instagram, and Flickr for media posts capturing “kelping” behaviour. Additionally, Wild Ocean Tasmania, Prolightmedia and A.E. Saner, provided drone recordings of three separate events of Australian humpback whales engaging with seaweed.

A total of 105 social media posts were carefully viewed to understand whether whales intently or coincidently interacted with seaweed. Most posts (67) derived from the northern hemisphere (Canada, US), and the remainder from Australia. Figure 1 illustrates the global distribution of kelp and where each interaction took place. 51% of all social media posts were published by whale watch companies, 41% by the public and 4% by citizen scientists.

Figure 1. Map of kelp distribution and locations of whale and seaweed interaction.


Nearly all seaweed interactions captured, were with humpback whales, but also grey (Eschrichtius robustus), northern (Eubalaena glacialis), and southern right whales (Eubalaena australis) were seen “kelping”. 53% of all documented interactions were carried out by adult whales, 14% by calves and unfortunately 32% could not be associated with any designated age group.

Whale and seaweed interaction was classified present if whales flexed their body towards the seaweed touching any of the three specified body parts (1-3) illustrated in Figure 2. Part one would extend from the tip of the rostrum to the base of the pectoral fin. Part two would continue to the base of the dorsal fin and part three would end at the fluke.

Figure 2. Body parts of a humpback whale, as well as the body sections (1-3) used to categorise the contact with seaweed.

Whales displayed a preference in touching the seaweed with their rostrum, but also with their pectoral fins and central body (Table 1).

Drone videos showed humpback whales lifting seaweed pieces onto their rostrum and dorsal fin, wrapping it around the fluke, swimming through or moving their pectoral fins through the seaweed (Figure 3). All three incidences displayed humpback whales actively and intentionally swimming towards the seaweed and maintaining a continuous and repetitive contact.

Figure 3. Humpback whale seaweed interaction showing different body parts, namely rostrum (a), fluke (b), dorsal fin (c), and pectoral fin (d) in contact with seaweed.

Humpback whales engaging with seaweed and explicitly addressing areas like rostrum, pectoral and dorsal fin suggests that their intention is solely to remove ectoparasites and to treat microbial infections. Paradoxically, neither of the whales showed any skin deterioration nor aimed for seaweed species with characteristic antibacterial properties.

For “kelping” to be acknowledged as a playful behaviour all criteria proposed by Burghardt (2005) need to be met. Accordingly, whales need to enjoy the activity, show an exaggerated and often incomplete display, without signs of stress, hunger, or illness. Such playful behaviour humpback whales have already shown in connection with driftwood and rope, as well as with jellyfish, dolphins, seals, and conspecifics.

Regardless, of what truly drives whales to interact with seaweed, this study has shown that social media can be a reliable source of information and complement scientific research. Social media posts can indeed help scientists unfold some of the great mysteries hidden in the “Big Blue”!

Cover image: humpback whale placing seaweed on rostrum (Meynecke & Kela, 2023).

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