What are the characteristics of the three wavy lines in the short article Snail and the Weather?

There is a new member in my family - a snail. It is very small and black, so I call it "Little Snail". It goes to bed early and gets up early every night. Every night, before I fall asleep, it is already "sleeping soundly" in that narrow little house; in the morning, I get up in a hurry to visit it, but I don't expect that it is already carrying a heavy weight on its back. The thick shell is "fitting out".

I remember one time, the science teacher asked us to observe a snail. I was so excited that I didn't even bother to take off my shoes. I went straight to the "little snail", picked up the magnifying glass and started observing. I looked at the head first and found that there are two pairs of tentacles, one pair long and one pair short. I heard from the teacher that the long tentacles of snails can sense changes in the surrounding environment, and the eyes are on the long tentacles, but they can only see in the dark. The place can be seen clearly. The short tentacles are used to find food. I carefully put some leaves in. Sure enough, I saw the snail touching it three times with its short tentacles. It was so interesting. I looked at the abdomen again and turned the snail over. I saw only white flowers and nothing. I checked the science book and realized that the snail's abdomen has gastropods that can help the snail crawl. Then I looked at the snail's tail. At this time, I saw mucus where it crawled. I quickly asked my mother where the mucus came from. What does it do? Mom said the mucus comes out of the tail, and the snail can move faster by following the mucus. Putting down the magnifying glass, I checked the primary school student encyclopedia to see if there was more relevant knowledge about snails.

Through observation, I know many secrets of snails. Students, as long as you observe carefully and carefully, you can discover more secrets!