Characteristics of insects (are spiders insects?)

      Insects are a type of arthropod with a body divided into three parts: head, thorax and abdomen. They have six legs and a pair of antennae. They are often called "bugs". Insects are widely distributed in various ecosystems on the earth. They are numerous and diverse, with about 1 million known species. They are the most abundant group of animals on the earth. Insects play an important role in the ecosystem, serving as herbivores, carnivores, decomposers, pollinators and pest control.

Speaking of insects, perhaps we are already familiar with them. Colorful butterflies, bees visiting flowers and making nectar, silkworms spinning silk cocoons, singing cicadas, aggressive crickets, starry fireflies, agile dragonflies that look like airplanes, simple and cute little ladybugs , a mantis holding a pair of big knives with angry eyes, annoying flies, mosquitoes, cockroaches, etc. So, what other insects are there? Are silk-spinning spiders and stinging scorpions insects? What about millipedes and centipedes? You may not be able to fully answer these questions. Now let’s take a look at what kind of insects are considered insects?

Insects, like other organisms, have their own special classification position. It belongs to the class Insecta in the phylum Arthropoda in the animal kingdom. Its main features are as follows (imitation color Wanzhi picture):

(1) The links of the body are assembled into three body segments: head, thorax and abdomen;

(2) The head is the sensory and feeding center, with mouthparts (mouth) and a pair of antennae, and usually compound eyes and a single eye;

(3) The chest is the center of movement, with 3 pairs of legs and usually 2 pairs of wings;

(4) The abdomen is the reproductive and metabolic center, which contains the genitals and most of the internal organs;

(5) Insects must undergo a series of internal and external morphological changes during their growth and development before they can transform into adults. This change in body shape is called metamorphosis.

Therefore, the basic characteristics of insects can be summarized as follows: "The body has three segments: head, thorax, and abdomen, 2 pairs of wings and 6 legs; 1 pair of antennae are born on the head, and the bones are wrapped outside the body; the shape changes throughout the life, and is found in prosperous families all over the world. "

With the concept of insects, you now know the answer to the previous question: the bodies of spiders and scorpions are divided into two sections, the cephalothorax and abdomen, and they also have 8 legs, so they are not insects. Centipedes and millipedes have even more legs, with one or two pairs of legs on almost every link (segment), and of course they are not insects.

animal tags： Insects dragonflies butterflies arthropods Insecta