Penguins spend almost half of their lives in the water. Observations and studies from New Zealand and the US scientists have shown that emperor penguins can spend longer periods of time under water in their search for food than was previously known. The researchers recorded that one of the animals was under water for more than 32 minutes. The previous record was just under 28 minutes. The dives were up to 450 meters deep.
Researchers are now puzzling over what drives the penguins to make such long dives. They suspect that foraging may have become more difficult. It is also possible that the penguins were off course and could not find an ice hole to surface. In their study, the researchers also wanted to know what enables penguins to hold their breath for so long.
It turned out that their special blood helps them in their excursions into the depths. This contains more hemoglobin than that of other birds. The protein takes up oxygen from the lungs and releases it to various tissues. The researchers wanted to find out more about the penguins’ haemoglobin. That’s why they recreated the protein of the last common ancestor – the original penguin, so to speak – in the laboratory and subjected it to various tests. This revealed two peculiarities: The penguins’ haemoglobin absorbs oxygen very easily in the lungs and also releases it easily in the acidic environment found in hard-working muscles. Thanks to this efficiency, the more than 30 minutes long dives of the emperor-penguin are possible, with which it holds the record among the birds.
Diving record of 514 meters
Another study recorded the behavior of emperor penguins in relation to diving depth. A team from Fukuyama University in Hiroshima, Japan, led by Shinichi Watanabe, succeeded in tracking the activities of ten emperor penguins. The survey took place at a colony on Cape Washington in the Ross Sea. With the help of special equipment, the researchers electronically recorded how the animals move and to what depths they dive.
They found that the penguins spend an average of just under five hours on the move after setting out to hunt. More than two thirds of the time they dived deeper than five meters, often to very great depths. The record of a penguin was 514 meters. Almost one third of the hunting phase the animals stayed on ice surfaces during short breaks. The longer the previous dive, the more time the penguins spent on the ice. Since the birds did not travel any significant distance on the ice floes, the researchers conclude that the animals use them primarily as recreational islands. At the same time, they also serve as protection against predators such as leopard seals.
Heiner Kubny, PolarJournal
Signore A, Tift M, Hoffmann F, Schmitt, T, Moriyama H, Storz J (2021) Evolved increases in hemoglobin-oxygen affinity and the Bohr effect coincided with the aquatic specialization of penguins, PNAS March 2021 118 (13). DOI: 10.1073/pnas.2023936118
Cassondra L. Williams, Max F. Czapanskiy, Jason S. John, Judy St Leger, Miriam Scadeng, Paul J. Ponganis; Cervical air sac oxygen profiles in diving emperor penguins: parabronchial ventilation and the respiratory oxygen store. J Exp Biol 1 January 2021; 224 (1): jeb230219. doi: https://doi.org/10.1242/jeb.230219