Revealing the special abilities of Sea King, how do aquatic organisms breathe underwater?

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 Revealing the special abilities of Sea King, how do aquatic organisms breathe underwater?


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Fish, jellyfish, starfish and sea cucumbers can absorb oxygen underwater. Hundreds of millions of years ago, humans and all the ancient ancestral species of terrestrial organisms with spines and limbs had the ability to breathe underwater, but when they completely began to live on land to absorb oxygen from the air, they gradually lost their ability to breathe underwater. Nowadays, people can only breathe underwater with special equipment, or people with special underwater survivability like the newly released sci-fi movie The Sea King.

Sea King tells the story of a half-human, half-Atlantic hybrid Sea King (played by Jason Moma) and how human-like Atlantis cousins breathe freely in the deep sea. The movie mentions gills. Although the story does not describe the structure of gills in detail, it impresses the audience. How do underwater organisms breathe in the water in real life?

In fact, there is a lot of dissolved oxygen in the earths oceans, lakes and rivers, but our lungs cant handle it at all. However, aquatic organisms in the world have evolved several ways of obtaining oxygen in water.

Ancient technology

Some organisms, such as jellyfish, absorb oxygen directly from water through their skin. Rebecca Helm, an associate professor at the University of North Carolina in the United States, says that the gastric circulation in jellyfish has a dual role in digesting food and handling the surrounding oxygen and carbon dioxide.

In fact, like jellyfish, the earliest oxygen-using microorganisms on Earth also gained oxygen by diffusion. According to marine scientist Juli Berwald, author of Invertebrate Life: Jellyfish Science and the Art of Spine Growth, this ancient underwater breathing may have occurred about 2.8 billion years ago.

Because they have only one outer cell layer and one inner cell layer, and their bodies are jelly-shaped and have no cells, they dont need cells, unlike other aquatic organisms, which need excessive oxygen to maintain the actual body tissues.

However, this underwater breathing through diffusion also has its drawbacks. This is slower than using a circulatory system to transport oxygen to the distal end of the body, which may mean that jellyfish growth is limited.

Backdoor approach

Echinoderms are marine organisms, including starfish, sea urchins and sea cucumbers, that breathe through oxygen diffusion on the surface of the body. According to Christopher Mah, an invertebrate zoologist at the National Museum of History, starfish can get oxygen when seawater flows through the protuberances and grooves in the skin called papulaes.

However, some sea cucumbers in shallow waters have different types of special adaptation to breathing - the respiratory dendritic cavity near the porta cava can absorb oxygen. When the rectal opening of sea cucumber sucks water into the body, the breathing tree extracts oxygen and expels carbon dioxide. Its just breathing on its butt, Mach said.

Breathing principle

According to the Northeast Fisheries Science Center, gill is a successful respiratory system for fish. It uses a network of blood vessels to inhale oxygen from running water and then diffuse through the gill membrane.

Solomon David, an associate professor in the Department of Biological Sciences at Nicholas State University, said: Most fish have the same working principle in their gills.

David said: They use the gills for reverse gas exchange - pumping oxygen out and releasing exhaust gas. When a fish opens its mouth, a stream of water flows through its gills, where reddish, highly vascularized tissues absorb oxygen and then emit carbon dioxide. Its kind of like capillaries in the human alveoli.

However, the gill does not absorb oxygen in all situations. The gill structure can vary among different species, and its ultimate goal is to meet the oxygen demand. For example, the gills of fast-swimming tuna differ greatly from those of less active and ambushing alligator eels. If an active predatory fish, they will always need different gills to adapt to high oxygen demand.

David adds that the shape of gills can even change between individuals of the same species, depending on the oxygen conditions in the waters they live in. Recent studies have shown that when fish aquatic environment is polluted, they adjust the gill shape. Over time, gill filaments become tighter, thus repelling pollutants in water. Some aquatic amphibians also have gills - branching structures extending from the head to the outside. Kirsten Hecht, an aquatic ecologist at the School of Natural Resources and Environment, University of Florida, says this is a larval feature of amphibians that will gradually disappear as most species mature, but some aquatic salamanders retain external gill structures. Until adulthood. Lung fish are fish that use modified swim bladders to get oxygen in water. Interestingly, when they are young, they have external gills, which disappear before all pulmonary fish species reach adulthood, Hector said. Source: Liable Editor of Netease Scientist: Qiao Junyi_NBJ11279

David adds that the shape of gills can even change between individuals of the same species, depending on the oxygen conditions in the waters they live in. Recent studies have shown that when fish aquatic environment is polluted, they adjust the gill shape. Over time, gill filaments become tighter, thus repelling pollutants in water.

Some aquatic amphibians also have gills - branching structures extending from the head to the outside. Kirsten Hecht, an aquatic ecologist at the School of Natural Resources and Environment, University of Florida, says this is a larval feature of amphibians that will gradually disappear as most species mature, but some aquatic salamanders retain external gill structures. Until adulthood.

Lung fish are fish that use modified swim bladders to get oxygen in water. Interestingly, when they are young, they have external gills, which disappear before all pulmonary fish species reach adulthood, Hector said.