Water Spider's 'Physical Lungs'

Spider is a typical terrestrial animal. But the water spider (also called the silver spider) is the only rebel of its kind - living in the world of water. When they dive into the water, many air bubbles will attach to the waterproof fluff all over their bodies, as if they have entered a sleeve with a closed air layer. This strange gas mask turns the water spider into a mercury ball, which is dazzling. Occasionally, they will use the end of their abdomen to poke out of the water and hold up a large bubble to show off. Water spiders are good at spinning webs among aquatic plants. Due to the storage of air bubbles under the web, the originally unfolded spider web becomes bell-shaped, like a small caisson. They set up camp in the caisson, and the female spider also lays eggs and hatches in it.

The bubble group possessed by the water spider is not only an oxygen storage device, but also an oxygen generator - it can continuously absorb oxygen from the surrounding water. This is what people call the "physical lung" oxygen supply device. During the breathing process, water spiders gradually reduce the oxygen concentration in the bubbles. Once the oxygen content is lower than 16%, the oxygen dissolved in the water will replenish the bubbles on its own. Usually when the spider is in a resting state, the physical lungs are enough to ensure oxygen supply; when the oxygen consumption is too large, the supply of oxygen-containing bubbles in the water will exceed demand, and the proportion of other gases in the bubbles will increase until it greatly exceeds that in the air. to the proportion in .

The result is that nitrogen begins to diffuse into the water, and the volume of the bubbles decreases accordingly (because the oxygen is used up). Eventually, the spider has to emerge from the water again to re-oxygenate the oxygen reservoir.

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