08.09.2025 – Fatty focus

People often ask us whether the weather makes a difference when it comes to encountering cetaceans out at sea. The truth is it does, but only for us (although larger storms can affect the surface time of the animals). When it comes to finding things we rely on our primary sense, which is vision and vision can easily be impaired by different conditions at sea. While toothed whales (Odontoceti) are visual animals, their primary sense is acoustic and relies on a unique organ in their foreheads known as the melon.

The melon is a globular shaped organ that is thought to act as a sound lens, focusing and modifying vocalisations according to their use. The generated bio sonar is basically used for everything, including navigation, hunting and communication.  The melon is made of fats (also known as lipids) and its shape, as well as its constituents depend on the species. While dolphin like Bottlenose dolphins (Tursiops truncatus) and Short-finned pilot whales (Globicephala macrorhnychus) have a melon with an outer and inner core, Sperm whales (Physeter macrocephalus) have two large filled oil sacs that stretch the entire length of their nose known as the spermaceti organ and the junk. Both have a function in modulating sound waves with the junk being homologous to the melon of dolphins but less valuable to whalers seeking out the precious spermaceti oil back in the whaling period (thus the name junk).

It’s difficult to imagine the world of animals with such a different sensory perspective of their world but the challenge of trying to do so makes every encounter with them so much more exhilarating.

By Paula Thake

Sightings of the day

Ribeira Brava

09:00 Bottlenose dolphins

Stenella

09:30 Bottlenose dolphins, Sperm whales

13:30 Bottlenose dolphins, Short-finned pilot whales, Sperm whales

16:30 Bottlenose dolphins, Short-finned pilot whales