Bamboo may explode when it is placed on a fire for barbecue. If you step on the swim bladder hard, it will explode.

1. Carbon dioxide is the main gas inside the bamboo joint.

2. The gas filled in the swim bladder is mainly oxygen, nitrogen and carbon dioxide, with the most oxygen content. Therefore, in an anoxic environment, the swim bladder can be used as an auxiliary respiratory organ to provide oxygen for fish.

People used to take the gas out of the swim bladder for experiments. It was found that swim bladder contains O2, N2 and CO2, among which O2 content is very high. When this gas is mixed with H2 and put into a glass tube, the glass tube is blown to pieces by electric spark.

So how is the gas generated in the swim bladder? The red gland, which is composed of microvessels in the inner layer of the swim bladder, secretes, and there is an oval window behind the swim bladder, which can discharge the gas in the swim bladder into adjacent blood vessels, and the gas in the swim bladder of the throat swim bladder can be directly inhaled and discharged from it.