Expain why deep sea fishes are not crushed by the pressure of all of the water above them.
I think maybe its because their density or mass is higher? Am I right?
You are partially correct! The main reason deep-sea fishes are not crushed by the pressure of water is not solely due to their density or mass, but rather their physiological adaptations. Let me explain.
The pressure at great depths in the ocean increases significantly due to the weight of all the water above. This can reach extreme levels, even as high as several hundred times the atmospheric pressure at the surface. However, deep-sea fishes are capable of surviving in such conditions due to their specialized anatomy.
Firstly, the bodies of deep-sea fishes are highly adapted to withstand pressure. They have sturdy, thick-walled bodies which are less compressible compared to their surroundings, allowing them to maintain their shape under immense pressure.
Secondly, the swim bladder, an organ that helps fishes control buoyancy, is either absent or reduced in deep-sea fishes. This adaptation prevents the swim bladder from being collapsed under the increased pressure, which could be very dangerous for the fish.
Additionally, the composition of deep-sea fishes' bodies plays a role. These fishes tend to have higher amounts of lipids (fats) in their tissues, which are less compressible compared to other organic materials. This helps to maintain their internal structures intact under pressure.
In summary, deep-sea fishes have evolved a combination of sturdy body structures, the absence or reduction of swim bladders, and specific body compositions to withstand the extreme pressure of the deep ocean waters.