Aarhus University Seal / Aarhus Universitets segl

Behaviour

Harbour porpoises and prey capturing


The harbour porpoise hunts 24 hours a day
Photo AU
Porpoise released after being tagged
Porpoise tagged and released. Photo by Esteban Iglesias Rivas
Diving profile from a porpoise. Red colour indicates echolocation.
This is a porpoise diving profile. The black and white color illustrates day and night and red marks the depth were the echolocation clicks were made. Animation made by Wisniewska et al., 2016

This is the story about a world class hunter

 

The harbour porpoise is the smallest cetacean in Danish waters. It costs a lot of energy for a tiny whale to live in cold water, especially in the wintertime when it has to build up an isolating layer of blubber. This is why it is so important for the porpoise to get enough to eat, and data recorded from acoustic data loggers and tags tell us that the harbour porpoise hunts almost 24 hours a day. Scientists found that the porpoise is a world-class hunter with a success rate of 90% of all hunted fish. With high energy loss in the cold water and the amount lost during foraging and social interactions, this success rate is highly important for the porpoise health, fitness and survival.

Read the scientific paper at:

This animation shows data recorded from a tagged harbour porpoise. It begins with the porpoise breathing at the surface, followed by it diving and starting to echolocate. During the dive, you hear a series of loud clicks with a high repetition rate, this indicates prey interaction. The animation ends with another trip to the surface and breathing. Wisniewska et al. 2016.

Potential sleeping behavior

Harbour porpoises (Phocoena phocoena)


Harbour porpoise with tag
Harbour porpoise with tag photo AU

Like many other cetaceans, harbour porpoises have developed a way to sleep without drowning. They actually only sleep with one half of the brain, while the other side keeps them breathing. Scientists here at the section of marine mammal research have tagged seven wild porpoises in 2010-2011 and found a very specialized diving pattern that could be connected to sleep. 

Access the full scientific article at ScienceDirect: