Whales and sea otters can hold their breath for a long time. How does this ability help them?
346480
They have breathing holes on their heads.When they need oxygen,they will swim onto the surface of the water and take in the oxygen.
479513
During pregnancy, there is a stage where the human fetus has gill slits, but by the time a baby is able to survive outside it's mother, these have disappeared.  Babies, as we would think of a baby, can NOT breathe underwater- they have air breathing lungs, just like you, and would drown.\n\nThere is something called the mammalian dive reflex, which slows respiration, and can allow someone to survive for a short time (perhaps a few minutes depending on the circumstances) under water just from the oxygen they receive from the water, however this works best in very cold water, which has more dissolved oxygen.  People with smaller bodies, like babies and young children are more likely to survive longer under water.  This is where stories of kids serviving under lakes for long periods (15 min, or so) come from.
171929
Birds air sacs allow them to have a larger "lung" capacity, therefor if humans had air sacs we would be able to run the mile in a shorter time b/c our bodies would theoretically be able to take in more oxygen.
33179
Sea turtles have low metabolic rates; that is, they have relatively low heartbeat frequency and breathing rate. Both the fact that they are poikilotherms and their usually large size contribute to this condition. The maximum apnea (no breathing) period recorded for a turtle (loggerhead turtle, Caretta caretta) is about 410 minutes (almost 7 hours); the capacity for holding their breath is lowered by stressful conditions or high activity.\nIn addition, at least some aquatic (freshwater) turtles can also breathe through the tegument of their pharynx or cloaca.
140188
I bet you could look this up on the web pretty easily. Why didn't you try?\n\nI bet the diffusivity is pretty good, however, because otherwise, how could fish breathe?
574261
Reptiles breath through thier skin.
621710
I think you can hold it longer underwater cause you have to for servivial. On land you can just breath through your nose.
641211
It's because they can't inhale and exhale at the same time. ;)
871829
Well, first they adjust their body to the pressure, by jumping into the water and staying for a period of time.  I believe the suit also has some effect.\n\nThe pressure of water compacts the body in a way, so I would think smaller lungs for breathing, muscle cramps, etc.
1042549
because they have gills that extract oxygen from the water, much like land animals have lungs that extract oxygen from the air.
375798
the blue whales excedes 4feet long
395427
Your heartrate will slow down as you keep holding your breath. Once you start breathing again, it will increase to above normal for a while and then settle back to normal.\n\n(Assuming you are not exerting additional force, such as swimming underwater)
370609
they react to the situation but dont feel it like mammals do.ask a fisherman they say the fish cant feel the hook but they do react to it
1128906
In a way--when they get beached, however that happens(I'm no scientist), the sheer weight of their bodies suffocates them, gradually.  The whales weigh so much, only water can support their bulk.\nI wish this were  not so, but it happens.
277970
If the baby seal wiggles too much, it is kind of difficult to get the skin off without poking a whole in it. They bop then on the head first. Whether that only knocks them out our kills them, I do not know for sure. Anyway it makes them hold still while they are relieved of their skin, so nice rich women can have a nice seal skin coat.
689395
All use thier kidneys, just as mammals do.\n\nSome seabirds (not all) also have special salt exctreting glands at the base of their beaks that helps them remove excess salt water.
445943
Breathin enables cellular respiration to continue.  Your body tightly regulated level of dissolved blood gases (i.e. CO2 and O2) by regulating your breathing rate.  In doign so it is able to keep these values within acceptable limtis and maintain homeostasis.