1. The puffer fish will swell up when it meets something that threatens its life or a predator. In order to scare off predators, puffer fish will quickly suck water or air into its elastic stomach when it is in danger in water, and expand several times in a short time, so as to scare off predators or make it difficult for predators to swallow.

2. Fishermen catch some puffer fish and fall into fish tanks. They often hear the squeaking of puffer fish. Look at the puffer fish in the fish pile. Their bellies are bulging like a ball. Some spiny puffer fish stand upright like hedgehogs.