How do fishes withstand the high pressure under the sea?

Question

What is the science behind the fishes that lets them withstand such high pressures under water

Answer 1

Their bodys have an equal pressure inside. Bring them up too fast, & they will blow up.

Answer 2

It's only a pressure differential that causes damage to an object. These fish are born, live and die at high pressure. Their internal body pressure is the same as the external water pressure. So they simply do not feel it at all. When these fish are brought up to a lesser depth, they may suffer the effects of low pressure, since their internal pressure is now higher than the external pressure. Something like a human being exposed to a vacuum. But as long as the internal and external pressures are the same, they don't have a problem.

Answer 3

The third answer is correct. The pressure inside a fish equals the pressure outside the fish. Only the difference between the two is of importance. The fish, as long as it is not changing depth, does not have to do anything and won't even notice.

What is amazing, though, is that many fish and many marine mammals can dive hundreds of meters in minutes and not suffer from the change in pressure. Humans would be injured and likely die if they tried to change their internal pressure so fast.

Answer 4

It is different for different animals.

One thing to remember is that fish don't need to breathe - they take oxygen directly from the water via their gills. One reason why humans cannot go too deep is because they cannot expand their lungs against the massive pressure, and so cannot breathe - even with SCUBA gear. Fish don't have this problem, and air-breathing oceanic animals like whales actually *collapse* their lungs and "hold their breath" while diving deep (this is called the "diving reflex").
Fish (and whales and humans) are mostly made of water - and water is non-compressible, so (breathing issues aside), they don't actually get crushed when under pressure.

Bony fish (ie - not sharks, rays, etc.) have a swim bladder that they can control the amount of gas in (by making it themselves). This allows them to regulate their buoyancy, and control the depth they stay at; if you bring a fish up too quickly, you can burst its swim bladder as the gas in it expands too quickly for them to compensate for.

Another problem - not from going down, but from coming back up - is "The Bends". High pressure forces gasses in your lungs to dissolve in your blood. This is normally fine, but when you come back up, they can come back out of solution - like a coke bottle fizzing when you release the pressure by opeing the lid. If humans don't come back up slowly enough, the gasses form air bubbles in your blood vessels, and can block them. This leads to severe muscle cramping, and can cause a heart attack or a stroke, if it happens in your heart or brain.
Fish, not having lungs, and exchanging across their gills, don't have this problem.
Whales collapse their lungs, so there is no "extra" gas to dissolve in their bloodstream.

That said - there are some deep bethnic (bottom-dwelling) animals that will die if you bring them up to the surface, and many near-surface animals will die if you put them under extreme pressure. This is usually due to minute air-bubbles within the animal, normally too small to be of concern, either expanding or contracting.

Answer 5

They adjust gradually to the pressure. If the are brought to the surface quickly, their swim bladders rupture.

Answer 6

their bodies are incredibly dense as well. they dont notice the pressure. we notice it because our bodies are so much less dense. the ocean water would crush us but their bodies are so dense, that their bodies actually push back on the water with the same force. so they dont feel any pressure at all.