Oxygen is vital to our survival. We constantly breathe in oxygen from the air to keep us alive. So how do organisms that live underwater survive without air? Read to find out!
Most marine creatures spend their entire lives below the surface of the ocean, surrounded by water. If we were underwater all the time, we would not be able to survive. What makes these organisms different from us?
The answer to this is a different method of breathing. Fish still need oxygen to survive, but they breathe in a completely different way from us!
Have you ever had a pet fish? Maybe you've noticed how fish constantly open their mouths as they swim around. This is actually how they breathe, by taking in oxygen from the water!
Water is made up of hydrogen and oxygen, which is why it's also commonly known as H2O! Since there is oxygen dissolved in the water, fish open their mouths to take in water and the oxygen is pushed through their gills, a special organ that humans don't have. Their gills have many blood vessels, and as the water passes through them, the oxygen enters their bloodstream. The carbon dioxide that is produced as waste leaves their gills and is then released into the water. Besides fish, there are other aquatic animals that also breathe through gills, such as amphibians (like frogs and toads).
What about aquatic animals who don't have gills, such as whales and dolphins? These two organisms are actually mammals, and they have lungs just like we do. They have blowholes on their backs, similar to how we have nostrils. To breathe, they come to the surface of the water and push their blowholes to be out of the water, allowing them to take in fresh air. Sometimes, you can see a spray of water coming out as they reach the surface to breathe!
Sea turtles also come to the surface to breathe. These animals have strong lungs that give them the ability to hold their breath for much longer than we can, from many minutes to even hours, allowing them to live under the sea.
Other animals such as starfish, sea starts, sea urchins and jellyfish also breathe in a different way! They absorb the oxygen in the water through the surface of their bodies.
Each sea creature breathes in oxygen from the water with its own unique system of organs. Even so, many creatures still need to come to the surface for air. It's all part of the amazing diversity of life!
Click on the attachment below for a sea animals coloring worksheet!
References:
“How Do Fish Breathe Underwater? | #aumsum #kids #science #education #children.”YouTube, uploaded by It’s AumSum Time, 14 Apr. 2018, www.youtube.com/watch?v=XEY2A5q1rxw.
“How Do Whales and Dolphins Breathe?”Whale & Dolphin Conservation USA, 16 Apr. 2020, us.whales.org/whales-dolphins/how-do-whales-and-dolphins-breathe.
“Information About Sea Turtles: Frequently Asked Questions – Sea Turtle Conservancy.”Sea Turtle Conservancy, conserveturtles.org/information-sea-turtles-frequently-asked-questions. Accessed 18 June 2020.
Weisberger, Mindy. “How Do Animals Breathe Underwater?”Live Science, 7 Dec. 2018, www.livescience.com/64260-breathing-underwater-aquaman.html.