What’s at Play: Humpback Whale Interaction with Seaweed Is a Global Phenomenon

Abstract

The use of objects by cetaceans is well known, and their ability to interact with their environment in complex behaviours has been demonstrated previously. However, baleen whales, including humpback whales (Megaptera novaeangliae), are less often observed to perform object use, but this behaviour might be more common than previously thought. Only a few isolated observations of interactions with seaweed have been reported in the scientific literature to date. The recovery of humpback whale populations, as well as the rise of technology such as unmanned aerial vehicles (UAVs) and the use of social media, allow for a new assessment of this object interaction. Here, we describe in detail three instances of “kelping” on the east coast of Australia derived from aerial observations. A summary of over 100 separate and unrelated events drawn from social media, documented by photographs and videos, suggests that this form of interaction with seaweed is observed across different populations. The form of interaction with seaweed is similar between regions, predominantly displayed between the rostrum and dorsal fin. This behaviour may be playful but could also serve additional benefits in the context of learning and socializing, as well as ectoparasite removal and skin treatment by utilizing brown algae’s antibacterial properties. Establishing this type of behaviour as distributed across different populations is important to better understand the species’ habitat preferences.

Keywords

• whales
• seaweed
• kelping
• humpback whales
• novel behaviour
• self-medication