What are the characteristics of spiders?

There are about 36,000 kinds of spiders in the world, the smallest is only 0.6 mm in length and the largest is 90 mm in length.

Spiders have no antennae and have six pairs of appendages on their heads and chests. The first pair of appendages, called claw limbs, are located in the front of the mouth, half-pincer-shaped, with sensory function and poisonous gland tubes inside. The second pair of appendages is called touching limbs. Spiders use these two pairs of appendages to bite or sting prey, inject venom and saliva containing digestive enzymes to anesthetize, poison and even decompose food, digest it in vitro, and then suck it. The other four pairs of appendages are walking feet and real moving organs.

Spiders weave webs to catch prey is a unique skill. Silk used to weave webs is secreted by the textile glands in the abdomen of spiders. Among web-forming spiders, their habits are different, and their web-forming shapes are also different, including awning nets, funnel nets, irregular nets, basin nets, etc., among which the most exquisite is the common wheel-shaped circular net, which is radial, just like the ancient gossip array.

Spiders eat a wide variety of insects, and sometimes even prey on birds several times larger than themselves, such as bird-eating spiders. Spiders in the field prey on agricultural pests, so they can play an important role in biological control.