Can a Shark Survive Without Swimming?

Quck answer

No, a shark will not drown if it stops moving because sharks use their gills to extract oxygen from water. Unlike humans, sharks do not need to constantly move to breathe. However, some species of sharks do need to swim continuously to keep water flowing over their gills in order to extract oxygen. These species include the great white shark, mako shark, and whale shark. Even then, these sharks can slow down or rest on the ocean floor without drowning as long as they are able to keep water moving over their gills.

Wild Animals

A sicklefin lemon shark swims over a coral reef on Jan. 21, 2021 in Moorea, French Polynesia, Pacific Ocean.
Alexis Rosenfeld/Getty Images

Sharks use their body to swim by waving it in side-to-side curves. This movement ripples down their torpedo-shaped body, pushing the water away and providing forward propulsion. However, it is a common myth that sharks will drown if they stop moving. This idea came about by comparing sharks to bony fish, which have many more muscles around their breathing apparatuses.

To breathe, sharks must remove oxygen from the water around them. The water enters the shark’s mouth and flows over the gills where the blood vessels absorb the oxygen. The excess water flows back out the shark’s body through gill slits. Sharks can extract about 80 percent of oxygen out of the meager 1 percent of oxygen that’s present in the water. To maintain a steady flow, the shark constantly needs to be taking in water. However, scientists have discovered that not all sharks have to stay moving to breathe.

Shark Breathing: Buccal Pumping and Ram Ventilation

There’s nothing wrong with this Port Jackson shark; it’s just buccal breathing.
Fred Bavendam/Minden Pictures/Getty Images

The oldest sharks, the modern sharks’ ancestors, all pumped water through their mouth and over their gills. This method is known as buccal pumping. Many sharks retain this method today, such as nurse sharks, angel sharks, and carpet sharks, also known as wobbegongs. Skates and rays, the shark’s cousins, also breathe this way. These species tend to spend most of their time lying on the bottom of the ocean floor.

Certain sharks have a unique way of breathing called buccal pumping, which involves using their face muscles to pull water into their mouth and then forcing it out through their gill slits. This method is commonly used by dorsoventrally flattened sharks such as the angel shark, which have a more prominent spiracle that acts as a mouth when they are buried at the ocean floor. However, as sharks evolved and became more active, ram ventilation became the primary method of breathing. This involves taking in water while swimming, which is more energy efficient. Some sharks have completely lost the ability to breathe by buccal pumping and are known as obligate ram breathers, including the great white shark, mako shark, salmon shark, and whale shark. These sharks must constantly swim and ram water through their gills to survive, and they increase their energy when faced with less oxygen. It is unclear how or when these sharks rest, but it is possible that their swimming is coordinated by their spinal cord rather than their brain. Despite the challenges of this constant movement, it is more work for these sharks to remain still than it is to swim, and they are able to alternate between breathing methods depending on their activity level.

Sharks have a unique way of getting rest by taking advantage of various factors that affect the oxygen level in water, such as salinity, temperature, and even the time of day. In Isla Mujeres, Mexico, researchers discovered the Caves of the Sleeping Sharks in the 1970s, where reef sharks were found motionless. The water in the caves had a high concentration of oxygen and reduced salinity, which made breathing easier for the sharks without having to move. Although they are not completely asleep like humans, many reef sharks have been observed resting at the bottom, even outside of caves. Scientists still do not fully understand how they are able to do this. Unfortunately, human activities such as illegal finning and getting caught in fishing nets can be fatal for sharks, especially for obligate ram ventilators. To learn more about the fascinating world of sharks, check out the links below. This article was originally published on June 9, 2008.

Additional Information

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• How Great White Sharks Work
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• Do whales and dolphins sleep?

Sources

• Bennetta, William J. “Deep Breathing.” The Textbook Letter. July-August 1996. (May 28, 2008)http://www.textbookleague.org/73shark.htm
• Bright, Michael. “Jaws: The National History of Sharks.” (May 28, 2008)http://www.fathom.com/course/21701777/session1.html
• Carlson, John K. and Glenn R. Parsons. “The effects of hypoxia on three sympatric shark species: physiological and behavioral responses.” Environmental Biology of Fishes. 2001.
• Carlson, John K., Kenneth J. Goldman and Christopher G. Lowe. “Metabolism, Energetic Demand, and Endothermy.” In: Carrier, Jeffrey C., John A. Musick and Michael R. Heithaus (eds.). “Biology of Sharks and their Relatives.” CRC Press. 2004. (May 28, 2008)http://web.bio.umassd.edu/dbernal/Coursedl/Carlson_et_al_2004.pdf
• Dingerkus, Guido. “The Shark Watchers’ Guide.” Wanderer Books. 1985.
• “Exploding Myths.” Nova. June 2002. (May 28, 2008)http://www.pbs.org/wgbh/nova/sharks/masters/myths2.html
• Knickle, C., L. Billingsley and K. DiVittorio. “Basking Shark.” Florida Museum of Natural History Ichthyology Department. (May 29, 2008)http://www.flmnh.ufl.edu/fish/Gallery/descript/baskingshark/baskingshark.html
• Lowe, Christopher G. and Kenneth J. Goldman. “Thermal and bioenergetics of elasmobranchs: bridging the gap.” Environmental Biology of Fishes. 2001.
• Martin, R. Aidan. “40 Winks Under the Sea.” ReefQuest Centre for Shark Research. (May 28, 2008)http://www.elasmo-research.org/education/topics/b_40_winks.htm
• Martin, R. Aidan. “How Do Sharks Swim When Asleep?” ReefQuest Centre for Shark Research. (May 28, 2008)http://www.elasmo-research.org/education/topics/b_sleep.htm
• Morrissey, John F. and Samuel H. Gruber. “So Excellent a Fishe.” Earthwatch. October 1989.
• Parker, Steve and Jane. “The Encyclopedia of Sharks.” Firefly Books. 2002.
• “Respiration.” Shark-Info.com (May 28, 2008)http://www.shark-info.com/shark-anatomy/shark-respiration.htm
• “Shark finning mystery.” Greenpeace International. Oct. 4, 2006. (May 29, 2008)http://www.greenpeace.org/international/news/shark-fin-mystery
• “Sharks and Rays.” SeaWorld InfoBook. (May 28, 2008)http://www.seaworld.org/Animal-info/info-books/sharks-&-rays/index.htm
• Young, Forrest A., Stephen M. Kajiura, Gerard J. Visser, Joao P.S. Correia, and Mark F.L. Smith. “Notes on the Long-Term Transport of the Scalloped Hammerhead Shark (Sphyrna lewini).” Zoo Biology. 2001. (May 27, 2008)http://www.flyingsharks.eu/literature/Notes_Long-term_Transport_S_lewini.pdf

FAQ

1. Can sharks breathe without moving?

Yes, sharks have to keep moving in order to breathe, but they don’t have to swim constantly. They can stay stationary by pumping water through their gills, which extracts oxygen from the water. So, sharks can breathe without moving as long as water is moving over their gills.

2. Do sharks sleep?

Yes, sharks do sleep, but not in the same way as humans. They have a state of rest called “tonic immobility,” in which they become still and relaxed, but still able to move and breathe. Some sharks have even been observed resting on the ocean floor.

3. What happens if a shark stops moving?

If a shark stops moving, it will not drown as it can still extract oxygen from the water through its gills. However, some species of shark do need to swim in order to keep water flowing over their gills. These sharks are called obligate ram ventilators, and if they stop moving, they will suffocate and die.

4. Can sharks swim backwards?

Most sharks cannot swim backwards, as their fins are not designed for that kind of movement. However, some species, such as the nurse shark and the lemon shark, are able to swim backwards by moving their fins in a different way.

5. Are sharks dangerous to humans?

While sharks are often portrayed as dangerous predators, they actually pose a very small risk to humans. Most shark attacks occur because the shark mistakes the human for its natural prey, such as a seal or a fish. However, it is important to exercise caution when swimming in areas where sharks are known to live.

6. How long can sharks live?

The lifespan of a shark varies depending on the species. Some can live for only a few years, while others can live for several decades. The oldest known shark was a Greenland shark that lived for over 400 years.

7. Can sharks get cancer?

Sharks have the ability to resist cancer, and very few cases of cancer have been found in sharks. Scientists are studying the immune systems of sharks in order to learn more about how they are able to resist cancer, with the hope of developing new treatments for humans.

8. What is the biggest shark in the world?

The biggest shark in the world is the whale shark, which can grow up to 40 feet long and weigh over 20 tons. Despite its massive size, the whale shark is a filter feeder and feeds mostly on plankton.