All spiders have eight legs. Like insects, which have six legs, spiders belong to the phylum Arthropoda but are members of a different class, Arachnida.
There are about 40,000 species of spiders. All species have two body segments instead of three as insects do, and all are carnivorous and venomous. All spiders also have the ability to make silk from their bodies and have specialized body parts called spinnerets that shape the silk as it is pushed out. Spiders use their silk to make traps for prey, to line burrows, to make safety lines, to make egg sacs and to fly through the air using the wind, a practice called "ballooning."