the Harbor seal
- Challenge: cold
- Strategy: wrap up well
- How? with a good layer of blubber
Seals have a 5cm layer of blubber under their skin, which keeps them feeling nice and warm, even when the water is ice-cold. With fat being such a good insulator, hardly any of their body heat escapes through this blubber at all, since fat is a poor energy conductor.
But what about newborn seal pups, who have no blubber under that highly desirable white fur? They have to make do with an internal ‘heater’: a reserve of brown fat between the shoulder blades, which generates a great deal of heat as it burns up. This is how a seal pup survives its first few days of life, until it builds up a healthy layer of blubber from its mother’s fat-rich milk. Of course, staying out of the water is extremely important too!
