Seals Don't Shiver in Chilly Waters

Animals pick different strategies for survival above and below the sea.

Diving headfirst into a tank of chilly water would cause even the most stoic of us to shiver, but not the hooded seal (Cystophora cristata). Although the plucky marine mammals shiver on cold, dry land, they stop as they plunge into nippy waters — a strategy that probably helps them to conserve oxygen and minimize the brain damage that could result from long dives.

Researchers have spent decades trying to fathom the seemingly impossible diving physiology of seals. The animals, which can spend up to 2 hours underwater in one dive, don't seem to be able to hold enough oxygen to allow them to survive this feat.