the spider is a type of animal with two body segments, four pairs of legs, no wings, and no chewing mouth. All types of spiders are classified into the order of Araneae; and along with scorpions, ketonggengs, mites-all eight-legged-were put into the Arachnida class. The field of study of spiders called arachnologi.


Araneae is the largest order in arachnids and ranks seventh in total species diversity among all organism order. Spiders can be found all over the world on every continent except inAntica, and have survived in almost all habitats with the exception of air and sea colonization. As of February 2016, at least 45,800 species and 114 spider tribes have been recorded by taxonomists. But there has been a schism within the scientific community about how all these tribes are classified because since 1900 there have been more than 20 different classifications have been proposed.


Spiders are predators (carnivores), sometimes even cannibals. Its main prey is insects. Almost all types of spiders, with the exception of about 150 species from the Uloboridae and Holarchaeidae tribes, and the Mesothelae suborder, are able to inject through a pair of fangs to their enemies or prey. However, out of tens of thousands of species, only about 200 species have bites that can harm humans. Not all spiders make a net to catch prey, but all are capable of producing silk threads-a thin but powerful strand of protein fiber-from a gland (called a spinneret) located at the back of its body. These silk fibers are very useful for helping the movement of spiders, swinging from place to place, trapping prey, making egg bags, protecting holes, etc.

Sense

The eyes of the spider are generally single eyes (single-lensed eyes), and not compound eyes as in insects. Most spiders have poor vision, can not distinguish colors, or are only sensitive to darkness and light. The spider of the cave is even blind. The exceptions are in some types of spider hunters who have sharp and good vision, including in recognizing the colors.

To mark the presence of its prey in general the spider relies on vibration, both on its sail net and on the soil, water, or place it occupies. There are also spiders that can feel the difference in air pressure. The spider's feelings lie in the hairs on his feet.

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