What helps a whale float and swim to the surface of the water?
First, let's talk about buoyancy or 'floatibility'. Let's think of what
happens when we drop a cork into water -- it floats. This means it is
positively buoyant. Something that sinks in the water is negatively buoyant.
Does that make sense? So, without getting too technical (since I don't know
how old you are or what grade of school you're in)...
The large layer of body fat that whales have is called blubber. It insulates
whales (keeps them warm), but is lighter in weight than water, and helps
whales float. But, whales cannot have too much of it. Too much positive
buoyancy would prevent these mammals from diving far below the surface.
Additionally, buoyancy of whales is affected by the volume (amount) of
gas-filled (air-filled) cavities (e.g., lungs). To counteract this buoyancy,
whales is a delicate balance of heavy muscle and bone. Bone and lean muscle
is heavier than water, sinks, and is therefore 'negatively buoyant'. The
gas-filled cavities (e.g., the lungs) change in volume with water pressure.
So, as a whale dives, the volume or space in the lungs compresses (becomes
smaller), which helps the whale become heavier, so to speak.
Now the really tricky part. Some whales conserve energy while diving by
gliding (or coasting) by using their tail, while right whales (a certain
species of whale) actually do the reverse and glide while they are ascending
There is a really cool experiment you can do to learn more about buoyancy.
Perhaps you can suggest it in school. See:
Hope this helps,
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