Will a shark drown if it stops moving?

Question

Will a shark drown if it stops moving?

Answer 1

yes, because they are denser than water.

whats funny about that question is that we did that in science. thats another story, though.

Answer 2

a great many species of shark, especially their cousins the skates and rays, spend long periods of time stationary and motionless on the bottom, not swimming at all. Many elasmobranchs pump water over their gills during respiration by the contraction of gill muscles sucking water into their mouth. Some species have small openings behind each eye called "spiracles," which work like a non-respiratory water pump drawing water into the oral cavity and over the gills. Those species, which have to swim forward to force water into and through their mouth to breathe, are called "ram ventilators." Ram-ventilating sharks will suffocate if trapped in nets or restricted from swimming when caught on a long line. The white shark is a ram ventilator and must remain swimming to ensure adequate water flow over the gills. Since bony fish possess a gas-filled swim bladder, they can remain stationary, or even move backward, by contracting their bony gill-plate cover (called the "operculum"), which they use to pump water over their gills.

Answer 3

NOT NECESSARILY. When it comes to oxygen intake, sharks use one (or both) of the following. One is 'buccal pumping' the other is 'ram ventilation'. Buccal pumping means that the shark draws water into its mouth and pumps it out through the gills, this is done using its 'buccal' or cheek muscles. This method requires NO forward movement and the shark can therefore be stationary and still breath. Examples of sharks that employ this method regularly are Angel sharks and Nurse sharks. The other method is one most of us are familiar with (although perhaps not in name). The majority of sharks employ 'ram ventilation' as the primary method of extracting oxygen from the water. This simply means that the shark swims along with its mouth partially open, the water rushes in and out over the gills extracting oxygen in the same way. Now as I have said the majority of sharks use ram ventilation as their primary method of breathing and indeed most 'ram ventilators' CANNOT perform buccal pumping as their facial muscles are not developed or adapted for this function. With these sharks it is ESSENTIAL that either they keep moving forward OR they must position themselves into a current sufficient to maintain a suitable amount of water flow. However, this all said sharks that use either method are both still able to rest. In the case of buccal pumping sharks, this function is maintained subconciously much like we breath subconsciously ALL the time and so these sharks can remain motionless for many hours. An experiment with a spiny dogfish (an obligate ram ventilator) indicated that swimming is coordinated by the spinal cord, not by the brain, so sharks may be able to shut down their brain and rest while still swimming. Moreover, it is actually more difficult for a ram ventilator to remain still and less efficient for oxygen extraction to do so. It is also well known that if a ram ventilator needs/wants to rest it will slow to the minimum speed necessary to maintain sufficient water flow and slow down all non-essential activity, this state may be referred to as 'sleep'. So if obligate ram ventilators are stationary and water flow (e.g. a current) is insufficient to extract the required amount of oxygen, then they will indeed drown. An example of how this can and does happen is getting caught in fishing nets.

Answer 4

Sharks move to flow water over the oxygen exchange membranes in the gills but, that is not the norm in the shark world ... there are some species that can actively pump water over their gills (buccal pumping and ram ventilation) when at rest.  Only about two dozen of the 400 identified shark species are required to maintain forward swimming motion to breathe (also known as obligate ram breathers).  Even those who must maintain forward motion can survive in external conditions that have higher concentrations of oxygen in the water and lower salinity (makes for more efficient oxygen exchange over the lamellae).  So, it varies depending on species (and how evolved they are) as to whether they will die if they stop swimming.

Answer 5

Yes

Answer 6

Yes in a way, but sharks expend more energy staying still than they do moving, so "laying down" for most species would be impractical. Scientists say that sharks swimming is not controlled by the brain, but the spinal column. So a shark can be swimming along and its brain can shut down and take a rest. While water is continuously passing over the gills.

Remember some sharks only take in about 1% of the available oxygen in the water around them, so moving is very important.