Spiders are predatory and prey mostly on insects. The number and arrangement of these eyes are major considerations in the classification of species. The end segment of each chelicera is fanglike and is connected to a venom gland. The legs have seven segments. At the tip of the opisthosoma are several fingerlike structures, known as spinnerets, which produce viscous droplets of silk from the silk glands, forming threads.
Spiders change little during growth, except in size.
If a leg is broken off during development, it is usually replaced. Spiders exhibit characteristic behaviours during and after courtship and mating, primarily because, unless the male clearly identifies himself, the female of certain species, commonly larger than the male, often kills and eats the male after mating. The eggs usually hatch soon after being laid. Insects, the main diet of most spiders, usually are captured in silken webs. In the webs of some species the strands are covered with droplets of a sticky substance that prevents or delays escape.