The seal instead of choosing something?
1992/10/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria
Why don't seals lie on the beaches? A Canadian biologist claims that it is not for not being in the sun, but for protecting yourself from predators and repairing skin...
Peter Watts, from British Columbia University, has just conducted three years of research on the common seal (Phoca vitulina). One result is that the risk of other seals feeding at sea until the first year ranges from 50% to 80%.
But living in the sea is more than living threatened, it is both good and bad, according to Watts. Combating waves and marine currents means a great energy expenditure. Water cools the skin from the focus and reduces the risk of disease.
Being on land also has its danger. For example, with excessive heating they can die. The heat conduction capacity of the air is 4% of the water capacity and also has a layer of fat to not lose heat in the water. The grease layer has a width of several centimeters and hinders the heat flow.
The color of the seal is dark, it does not have the ability to sweat and the fins do not expel more than 30% of the body heat, so the heat accumulates easily. On sunny days they can heat more than 15ºC in half an hour.
Watts has discovered that seals, when they are on the beaches, have many ways to combat overheating. He quantified the existing seals in the Puget Sound islands of Seattle and calculated for each island the “heat flow index”, a combination of solar radiation, air speed and air temperature.
He discovered that seals avoided the islands with the highest heat flow. He found that the hours of disembarkation vary according to the time of year. In spring, although they go to the beach at noon, in summer they usually go to the afternoon.