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Most sharks need to constantly swim in order to breathe and cannot sleep very long without sinking (if at all). However, certain species, like the nurse shark , are capable of pumping water across their gills, allowing them to rest on the ocean bottom.
All sharks need to keep water flowing over their gills in order for them to breathe; however, not all species need to be moving to do this. Those that are able to breathe while not swimming do so by using their spiracles to force water over their gills, thereby allowing them to extract oxygen from the water.
Some species of sharks use this system. When they swim, water flows into the mouth and across the gills. Because these sharks rely on this technique, they must keep swimming in order to respire. Bony fish use countercurrent flow to maximize the intake of oxygen that can diffuse through the gill. Countercurrent flow occurs when deoxygenated ...
Sedentary, bottom-dwelling sharks generally use buccal pumping to move water over to their gills compared to more active sharks, who will use ram ventilation and swim to force water to their mouth and gills. Most sharks can switch between these mechanisms as the situation requires depending on the abundance of oxygen in the water.
Most sharks rely on ram ventilation, forcing water into the mouth and over the gills by rapidly swimming forward. In slow-moving or bottom-dwelling species, especially among skates and rays, the spiracle may be enlarged, and the fish breathes by sucking water through this opening, instead of through the mouth.
But a world without sharks isn't an impossible reality: Over 100 million sharks are currently removed from oceans each year due to overfishing and bycatch. Kinsler says sharks may be an apex ...
While at rest, most sharks pump water over their gills to ensure a constant supply of oxygenated water. A small number of species have lost the ability to pump water through their gills and must swim without rest. These species are obligate ram ventilators and would presumably asphyxiate if unable to move. Obligate ram ventilation is also true ...
Without sharks, the ecosystem would be thrown off, triggering changes to the ocean as we know it. Awareness and support of the overfishing problems and the risk of extinction are critical for ...