Spider's body is mainly composed of three parts: head, chest and abdomen. There are 8 eyes in the head, which are distributed in two rows; The two claws can easily catch the prey, and the spider completes the swallowing process of the prey through the mouthparts and chewing muscles; The chest is the main motor organ of the spider, 6 pairs of legs and 1 pair of big teeth are connected with the chest, and the nerve centers of the spider's vision, touch and taste are concentrated in the chest; Inside the abdomen are the digestive system, reproductive organs, respiratory organs and fixed organs.

2. The growth process of spiders

Spider is a kind of arthropod, so its growth process is different from that of vertebrate. Spiders grow by molting, and the time interval and frequency of molting each time are related to spider species, growth environment and other factors. Most larvae can molt 5- 10 times, while adult spiders generally don't need to molt or molt very few times. Every time after molting, the spider's skin will harden into a shell, and the new spider's body surface will gradually harden in a short time.

In addition, spiders need to absorb enough nutrients to meet the growth and development of the body during their growth. Therefore, on the one hand, spiders are looking for nutrition, on the other hand, they also play the role of being hunted by food to meet the balance of the food chain.

3. Composition of spider venom

Spiders kill prey by injecting venom into their teeth. Its venom is mainly composed of protease, neurotoxin and other components. Protease acts on the internal tissues of prey and breaks them, destroying the cellular structure of prey, making prey unable to escape the subsequent attacks of spiders; Neurotoxins act on the nervous system of prey, making its muscles stiff and unable to move, so that spiders can easily swallow their prey.

Different kinds of spiders have different venom components. For example, the venom of some spiders contains ingredients related to pain, which makes their prey suffer greatly; There are also some spiders whose venom contains low concentrations of preservatives, which can keep the carcasses of their prey fresh for a long time.

4. Characteristics of spider silk

Spider silk is their defense and hunting weapon. Spider silk is mainly composed of protein. Spiders have four pairs of spider silk glands, and the spider silk secreted by each pair of glands has different components and uses, such as weaving webs, nesting and wrapping prey. Spider silk of different glands also has different characteristics, for example, some spider silk is tough and can resist strong pulling force; Some spiders' silk becomes more viscous when exposed to water, and it is easier to catch nutrients in the water.

Spider's spider silk structure is also very fine, and the fiber content and shape of spider silk can be adjusted according to the environment and needs to adapt to different scenes. Spider silk is a very magical substance, which is not only used in textile and medical fields, but also provides us with a key to understand the mysteries of nature.