[填空题]
Spiders
Spiders can be distinguished from other arachnids because the prosoma (combined head and thorax) is only separated from the opisthosoma (abdomen) by a narrow waist, in other arachnids the whole body appears to be much more of a single unit. All spiders produce silk, but only some construct webs to catch their homes and to protect their eggs.
All spiders possess poison glands but very few of them are dangerous to humans, of the 600 species in Britain only 12 (at least one of these is a recent human assisted colonist) are strong enough to pierce the human skin, and apart from allergies, none are more dangerous than a common wasp. Most spiders have 8 eyes (though some have 6,4,2 or 0), as well as 8 legs. (By the way if you count the claws as separate leg section( which you shouldn’t really)then their legs have 8 parts as well( coxa, trochanter, femur, patella, tibia, tarsus, metatarsus, claws). There are more than 32 000 kno
