Swim bladder

Internal organ contributing to the buoyancy of the fish.

The natatory bladder is an organ which is in certain fish and which allows them to control their buoyancy and their position in the water. It is filled with air and is generally found in the abdominal region, near the spine.

The natatory bladder can be inflated or deflated thanks to specialized muscles and secreting channels that allow the air volume it contains to be regulated. When swollen, the natatory bladder allows the fish to stay on the surface of the water or to rise to the surface if it plunges too deeply. When deflated, the fish can descend more deeply into the water.

In addition to controlling buoyancy, the natatory bladder also plays an important role in regulating the internal pressure of the fish. Indeed, when the fish plunges to larger depths, the water pressure increases and can cause damage to the fish body if it is not properly offset. The natatory bladder helps to regulate this pressure by inflating or deflating according to the needs of the fish.

Some species of fish have a more developed swim bladder than others. For example, fish that live mainly in shallow waters and spend a lot of time on the surface generally have a very well developed birthday bladder. This allows them to stay on the surface without spending too much energy. Other species, such as predatory fish, have a less developed natatory bladder because they spend less time on the surface and must be able to dive quickly and maneuver in the water effectively.

In summary, the natatory bladder is an essential organ for the survival and well-being of fish. It allows them to control their buoyancy and their position in water, as well as regulate the internal pressure of their body when they plunge at significant depths.