Fish that can live without water

Fish rely on their gills to breathe oxygen dissolved in the water, so they cannot live without water and will die quickly once they leave the water. Species with larger gill openings usually die faster than those with smaller gill openings. But there are a few fish that can live out of water for a long time, because in addition to their gills as their main respiratory organs, these fish also have accessory respiratory organs to assist in breathing, so they can leave the water without dying.

As we all know, fish such as climbing bass, fighting fish, snakehead, and bearded catfish can stay out of water for a long time without dying. In addition to their strong vitality, these fish mainly have two organs called epibranchial organs on the left and right sides of the gill chamber. The structure of the accessory respiratory organs and epibranchial organs varies from species to species. The epibranchial organ has a well-developed air breathing function. As long as the organ remains moist, it can absorb air from the air and maintain the life activities of the fish.

There is a group of cystobranchial fish in India. Its epibranchial organs turn into a pair of long tubular sacs, which pass from the gill openings back through the muscles near the spine to the tail. There are abundant blood vessels on the inner wall of the sacs, and the sacs are filled with air, so they can Live away from the water for a while.

The skin of eels, catfish, mudskippers, eels, loaches, etc. has a respiratory function. The skin of these fish is rich in blood vessels, and gas can penetrate the skin and enter the blood.

In addition to the eel's skin being able to breathe air, the epithelial cells on the inner wall of its oropharyngeal cavity are covered with blood vessels and can directly breathe air. The eel's gills have degraded and cannot complete water respiration independently. It can only survive by relying on this air-assisted respiratory structure. Therefore, eels always lift their heads out of the water to breathe.

In addition to the ability of the loach to breathe air through its skin, its intestines have a strong ability to breathe. The intestinal wall of the loach is very thin and densely covered with blood vessels. When there is insufficient dissolved oxygen in the water, it will surface and suck in air from its mouth. Gas exchange occurs in the tube, and waste gas is discharged from the anus. Normal intestinal respiration accounts for about 1/3 of the total oxygen intake. When the weather is hot, the atmospheric pressure is low, and there is a lack of dissolved oxygen in the water, loaches in the water will rise to the surface to inhale, one after another, so loaches are called "climate fish" in Europe.

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