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How Do Sharks Pee

How do sharks pee

You may be wondering – how do sharks pee if they live in water? Unlike land mammals, sharks have a unique way of excreting waste products from their bloodstream. In this article, we’ll dive into the shark’s specialized pee process.

See also: How do sharks poop?

Osmoregulation in Sharks

Osmoregulation is the process that marine fish like sharks use to maintain proper levels of water and salt in their bodies. Since seawater contains much higher salt levels compared to the fluids inside a shark, they are constantly at risk of dehydration.

To counteract this, sharks have an organ called the rectal gland that filters out excess salts, minerals, and urea from their blood. Located near the cloaca, the rectal gland removes these substances and passes them into the intestines to be expelled.

Unique Pee Strategy

Instead of releasing a concentrated stream of urine like mammals do, sharks excrete urea and other wastes diffusely through their skin and gills in a process called urea flux.

Here’s how it works:

  • Urea is produced by the liver as a waste product of protein metabolism
  • The high urea concentration in the blood allows it to diffuse through the shark’s dermal layers
  • Urea exits the shark’s body through the skin’s surface into the surrounding seawater

Since sharks do not have sweat glands or salivary glands, urea flux serves as their version of sweating to prevent dehydration.

Benefits of Urea Release

Releasing urea directly through their skin allows sharks to:

  • Maintain appropriate water and salt balance in the body
  • Quickly excrete nitrogenous waste products from protein digestion
  • Avoid large losses of water into the hyperosmotic seawater environment

Urea also helps increase buoyancy which reduces the energy sharks need to swim and stay suspended.


So next time you see a shark, remember that its skin is doing the job of a kidney! A shark’s multifunctional dermal layers allow it to urinate in this unique diffusion-based manner.

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Steve Momot

Steve is an accomplished professional photographer and marketer who specializes in the Fishing, Yacht, and Boating industry. With a strong presence as an influencer and marketing expert in the Marine Industry, he has made a significant impact in the field. Additionally, Steve is the original creator and co-founder of Sportfishtrader. Prior to his career as a marine photographer, he gained extensive experience as a licensed boat and car dealer in South Florida.

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