Science Tips Chapter 2

1. Why can't ostriches fly? Ostrich is a kind of bird with a huge body, but they can't fly into the sky! This is not because their wings are useless, but because their feathers are too soft and their wings are too small, which is not suitable for flying at all. In addition, the muscles of ostriches are not well developed and the sternum is flat, which is not helpful for flying. Ostrich lives in Africa. Because they have lived in desert areas for a long time, their bodies have gradually evolved into their current appearance in order to adapt to the environment.

2. Why don't canned foods spoil easily? Luncheon meat, salted fish with black beans, beans in tomato sauce... are all delicious canned foods, and they can be stored for a long time without spoiling easily. This is because the cans are sealed and bacteria cannot enter. When people make canned food, they extract all the air in the cans and then seal them. In the absence of air, even if the food inside is contaminated with a little bacteria, they cannot survive or reproduce!

3. Why do babies cry non-stop when they are just born? Babies cry loudly when they are just born. This is not because they are unhappy, but because they are breathing in their first breath of air! When babies leave their mothers' bodies and are born, the first breath of air they take in will rush to the throat, which will violently impact the vocal cords, causing them to vibrate and then make a sound similar to crying.

4. Why does the lizard's tail continue to bounce after it breaks off? In order to protect themselves, many lizards also use protective colors to hide their presence; and when some lizards are attacked, their tails will break off due to violent muscle contraction. Since some nerves are still alive in the broken tail, it will continue to bounce, thereby distracting the enemy's attention and escaping. Don't think that their lives will end like this. In fact, it only takes a few months for the tail to grow back and continue to live.

5. Why do squirrels have particularly large tails? Don't underestimate the squirrel's tail! While the squirrel is jumping around in the tree, its tail is playing a big role. It can keep the squirrel balanced when jumping on the tree and avoid falling and getting injured. In addition, this big tail can also play a protective role in winter, tightly surrounding the squirrel's body, which is both convenient and practical.

6. Why can't a person's thumb have one or three joints? Most people have five fingers, and the lengths of their fingers vary. But has anyone noticed that, in addition to the thumb, the other fingers also have three joints, but the thumb has only two joints? It turns out that the number of joints is just right for the other four fingers. If it had three joints, the thumb would appear weak and unable to lift heavier objects; if it had only one joint, it would not be able to freely cooperate with the other four fingers to hold things tightly!

7. Why don't you feel itchy when you scratch yourself? When others scratch ourselves, we feel itchy and laugh constantly; however, when we scratch ourselves, we not only don't laugh, but also don't feel itchy. Because we are mentally prepared, the brain will send a message of "no danger", and the nerves will relax accordingly, so we won't laugh and feel itchy!

8. Why is the sea water mostly blue and green? Looking at the sea, we often find that the sea water is blue and green. However, when you scoop up the seawater, you can only see that it is transparent and colorless like the water of the past. It turns out that the seawater itself is not much different from the water we come into contact with in our daily lives, and it is also transparent. The green color we see is actually a phenomenon caused by the seawater's ability to absorb light. Only green light can be absorbed by the seawater and then reflected; when the seawater is deeper, the green light is also absorbed, and the seawater looks blue.