How many legs does a spider have?

Eight legs, and that count is the quickest way to settle the argument about whether a spider is an insect. It is not. Insects have six legs, three body sections, usually antennae and often wings. Spiders have eight legs, two body sections, no antennae and never wings - they are arachnids, alongside scorpions, mites and ticks.

Rather more surprising is how the legs work. A spider has muscles to fold its legs inwards but very few to push them out again. It extends them hydraulically, by pumping body fluid into the limb under pressure. This is why a dead spider curls up: the pressure fails and nothing is left to hold the legs open.

Most spiders also have eight eyes, arranged in patterns that specialists use to tell families apart, and most produce silk from spinnerets whether or not they build a web - for wrapping prey, lining burrows, protecting eggs, or spinning a line to drift away on the wind.