What are the characteristics of insects? A comprehensive analysis of the main features of insects

Insects are not only numerous in species, but the number of individuals within a single species is also astonishing. The distribution of insects is so wide that no other class of animals can compare with them, covering almost the entire Earth, and they are divided into different species. Do you know what characteristics they all have? Let us take a look at the characteristics of insects together!

Characteristics of insects

1. The body has a shell-like structure on the outside, so it is usually relatively hard.

2. Externally, segments can be clearly identified.

3. The head, thorax and abdomen can be clearly distinguished as three parts.

4. The head usually has a pair of antennae, a pair of eyes (compound eyes) and a mouthpart.

5. The upper part of the thorax usually has two pairs of wings, while the lower part usually has three pairs of legs (feet).

If all the conditions match the characteristics above, we can say: it is an insect! However, this does not mean that all insects possess these characteristics. There are still many insects that lack some of these features. For example, some insects have only one pair of wings or even no wings at all, some insects have no eyes, some insects are missing a pair of legs or have no legs at all, some insects have soft bodies, and so on.

The structure of insects

The body of an insect looks as if it is joined together segment by segment, which is also why they are called arthropods. Now let us observe the structure of insects a little more carefully. First, their bodies can be divided into three main parts: the head, thorax and abdomen.

1. Head

① Antennae: A pair of antennae grows at the front upper part of the head, and their shape varies greatly with the species of insect. The antennae are like a person's nose, mainly used for smelling odours; in addition, the antennae of some insects have the function of sensing air vibrations.

② Compound eyes: A pair of compound eyes grows on the two sides of the head. They are formed by the gathering of many tiny small eyes. The function of compound eyes is the same as our eyes, used for seeing things. Their structure also often changes with the species of insect.

③ Simple eyes: Simple eyes are a very inconspicuous structure, located between the two compound eyes. Although they are a kind of eye, insects do not use them to see things, but use them to help the compound eyes distinguish light and dark objects. In some insects they are even reduced and absent.

④ Mouthparts: Mouthparts are the mouth of an insect, used for eating. The most common mouthparts are of two kinds. One is like the mouthparts of a locust, with two large mandibles used for cutting food into pieces; the other kind, like the mouthparts of a mosquito, is needle-shaped and can pierce the skin to suck blood. In addition, mouthparts may vary with the species of insect.
2. Thorax

The thorax is where the main locomotor organs of an insect are located. Externally it can be divided into three segments, namely the prothorax, mesothorax and metathorax. On both sides below each thoracic segment grows a pair of legs, so the three thoracic segments together have three pairs (six) of legs. In addition, above the mesothorax and metathorax there is usually one pair of wings on each, so insects generally have two pairs (four) of wings.

① Wings: Wings are the structures insects use for flying; however, like other structures, wings also vary noticeably with the species of insect.

② Legs: Legs are what insects use for crawling; however, the legs of some insects have different functions, such as digging, grasping or catching, and so on.

3. Abdomen

Compared with the previous two parts, the structure of an insect's abdomen is relatively simple, without too many appendages. The more obvious structure should be the genitalia located at the end, the male's copulatory organ or the female's ovipositor.

Up to the early 21st century, humans had about 1,000,000 known species of insects, but there are still many species waiting to be discovered. Well, that is all for the introduction to the characteristics of insects!