Why do sharks need to constantly swim to breathe?

What are spiracles in sharks and what is their function?

Sharks have multiple spiracles located on the top of their heads, which are small openings that allow water to enter the respiratory system.

Answer:

The spiracles in sharks help to draw water into the respiratory system, allowing the shark to breathe efficiently.

Unlike most bony fish, which use their mouth to breathe, sharks have a separate respiratory system that relies on water flowing over their gills to extract oxygen from the water.

Most sharks have to constantly swim, or at least move forward, in order to breathe. This is because they rely on a constant flow of water over their gills to extract oxygen from the water. If they stop moving, water flow over their gills decreases, and they may suffocate.

However, some shark species, such as nurse sharks and whale sharks, are able to pump water over their gills even when stationary, allowing them to rest on the ocean floor without suffocating.

The ability to stop swimming also depends on the species of shark and their individual biology. Sharks that can stop swimming typically have adaptations that allow them to pump water over their gills even when stationary, or they may be able to extract oxygen from the water in other ways, such as through their skin.

Some species of sharks, such as great white sharks, may be able to slow down their swimming or even rest briefly without suffocating, but they still need to keep moving most of the time to maintain a constant flow of oxygen-rich water over their gills.