July 11, 2013 — Scientists at the Universities of Liverpool, Plymouth, and Radboud, Netherlands, have challenged the view that giant animals are found in polar seas because of a superabundance of oxygen in cold water.
It is thought that giant insects and other creatures hundreds of millions of years ago evolved due to a superabundance of oxygen and that this could also explain the existence of giant sea creatures today. The new research, published in Functional Ecology, however, suggests that this may not be the case.
Survive despite low oxygen supply
The research suggests that large animals survive in polar oceans despite there being low oxygen supply. They showed that giant body sizes have an advantage in the cold conditions by being better able to regulate how much oxygen they take up.
Dr David Atkinson, from the University's of Liverpool's Institute of Integrative Biology, explains: "It is true that cold water holds more oxygen than warm water, but the speed at which it diffuses is so slow that cold water actually lowers oxygen availability.
"To understand why animals reach gigantic proportions in cold oceans, we looked at how oxygen-containing water moves over the body surfaces of animals. We noted that as water is much denser than air, it is much harder for animals to move oxygen-containing water over the body surfaces that take up this essential fuel. This is crucial as this movement prevents a thick layer of stagnant water clinging to the body and asphyxiating a water-breathing animal."
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