Photo courtesy of Nuala Moore, inside the Arctic Circle in Murmansk.

When scientists discovered the first warm-bodied fish [see below], it reminded us of the selected representatives of mankind who are willingly subjecting themselves to unprecedented distances in nearly ice cold water without protection.

It is a new world.

When fish are found to be warm-blooded and mankind is found to flourish in frigid waters, it is a world that we did not grow up in and we could never imagine as a child in elementary school.

It is an entirely brand new world.

The opah can keep its body warm similar to mammals despite living in cold deep waters of the oceans. The opah generates heat from its pectoral muscles and conserves its warmth due to body fat.

This opah sounds like the human-like ice swimmers who manage to keep their bodies relatively warm despite competing in the cold waters of frozen lakes. Like the opah, the ice swimmers generate heat from their muscles. We wonder if in the course of the human’s acclimatization to the cold water, these swimmers develop specific physiological adaptations like the opal’s evolved blood vessels in its gills.

“It’s a remarkable adaptation for a fish,” says Diego Bernal, a fish physiologist.

Years ago, we were taught that fish are cold-blooded and people would die in water under 5°C over extended periods of time. But we now know that neither of these are true.

It is for certain that not only will scientists continue to learn more about the marine world, but we expect that swimmers in the future will continue to push the boundaries in the cold water.

Copyright © 2015 by World Open Water Swimming Association