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Insects

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My favorite TV channel is the Shanghai Documentary Channel because I can always enjoy watching the graceful creatures it features. Today, I'd like to introduce one type of creature: insects.

First, let’s think about what an insect is. Is a butterfly an insect? Is a spider an insect?

nsects belong to the Arthropoda phylum. Therefore, an insect must have all the characteristics of an arthropod. An arthropod has the following features: First, its body is divided into several segments. Second, it has legs that are also segmented. Now we know neither the earthworm nor the snail is an arthropod because they lack legs. Are humans arthropods? We have legs, but no! An arthropod has an exoskeleton, meaning their bones are on the outside of their bodies, whereas our bones are inside. Let's count how many arthropods we know: shrimps, crabs, spiders, butterflies, bees, ants—all of these are arthropods. But only some of them are insects.

So, what sets insects apart?

An insect’s body has three parts: the head, the thorax, and the abdomen. The head is the sensory center, equipped with a pair of antennae and eyes. Some insects have one or two pairs of eyes, while others have thousands of eyes. Another function of the head is to consume food. The thorax is the locomotive center of an insect, with three pairs of legs attached. The abdomen is responsible for reproduction and metabolism. Metabolism involves absorbing food and excreting waste from the body.

From this, we know a spider is not an insect because it has four pairs of legs. However, butterflies, bees, ants, dragonflies, and mosquitoes are insects. Have you ever observed caterpillars? Some have thousands of legs, while others don’t have any. Yet they are still considered insects because these characteristics describe the imago, a mature insect. Caterpillars are only larvae and will metamorphose into butterflies eventually.

Do you know how many species of insects exist on Earth? Some believe there are more than 10 million species. Considering only the discovered species, if all species of creatures on Earth were represented in one pie, about 1 million species, three-fourths of the pie would be occupied by insects. One-third of these insects are beetles. One-sixth are butterflies, another sixth are bees and ants, another sixth are flies and mosquitoes, and the remaining sixth are other insects.

You may be curious why there are so many kinds of insects. I know some of the reasons:

  1. For hundreds of millions of years, insects were the only creatures on Earth that could fly until birds emerged. They could easily migrate to other habitats or escape their enemies with the help of their wings. Insects exploit every possible niche once they arrive on Earth.

  2. The size of an insect is usually tiny. The largest insect is about the size of an egg. For the smallest ones, 10 million of them together weigh about as much as one egg. This means an insect requires only a minimal amount of food to survive. For example, a cockroach can live for two months without eating anything. Additionally, they can hide almost anywhere.

  3. Almost anything can be food for insects. A cockroach can live its entire life inside a television set by eating the wax on the circuit board.

  4. Insects have an incredible reproductive capability. On average, an insect can lay hundreds of eggs at a time, and some can lay millions of eggs.

  5. The first insects appeared 350 million years ago. Over this vast period, insects have adapted perfectly to the world. They have evolved various capabilities to protect themselves, some of which are hard to imagine. For example, some insects can live in deserts where temperatures exceed 50°C (122°F), while others can survive in environments as cold as -50°C (-58°F). Some flies can live in pure salt, pure oil, or even pure carbon dioxide.

Insects are truly remarkable creatures. Their diversity, adaptability, and resilience have allowed them to thrive for millions of years. Whether you’re fascinated by their biology, their role in ecosystems, or simply their beauty, there’s no denying that insects are an essential part of our world. Next time you see a butterfly, a beetle, or even a humble ant, take a moment to appreciate the incredible complexity of these tiny wonders.