Thick fur, heavy under coat, thick layer of fat or blubber but not necessarily all of these.
they would get very cold and then freeze after a long time
That depends on whether the vertebrate is warm or cold blooded. Animals such as fish and amphibians have to be able to survive with a body temperature similar to their surroundings, because they are cold blooded and they can't leave the water long enough to really warm up. Reptiles are cold blooded, but they can warm up by basking in sunlight. Mammals and birds are warm bloded, so they generate heat internally from the energy they get from food.
Of course camels swallow their food, as all mammals do- they have no other way of ingesting it. However, they are able to store the water they drink in tissue within the humps on their backs, which is why they are able to survive in desert conditions for so long, where water is scarce.
Dugongs are aquatic mammals, they spend their whole life in the water.
yes,most species do.otherwise,the would not be able to tolerate cold water for long,and they would get water logged,making them easy prey.
most of them
We have body hair and can survive for long durations away from water. Safe to say we're mammals.
3 to 5 days.
Hypothermia
Hypothermia.
yes a brown bear can hold their breath under water, it might sound kind of impossible, but their able to do it
It will certainly not stay cold as long as if it were capped.