Spiders (order Araneae) are air-breathing arthropods with eight limbs, venom-injecting fangs, and silk-spinning spinnerets, found on every continent except Antarctica, with over 53,000 species recorded. Unlike insects, they lack antennae and extend their limbs using hydraulic pressure, and their lineage dates back to the Devonian period (~386 million years ago), with true spiders appearing in the Carboniferous. They are primarily predators, using strategies like sticky webs, bolas, and active hunting to capture prey, collectively killing an estimated 400–800 million tons of prey each year—though Bagheera kiplingi is a notable herbivorous exception. To avoid being eaten by their larger mates, males perform complex courtship rituals, and females often care for their young in silk egg cases. While most are solitary, a minority of species are highly social, building communal webs that can house up to 50,000 individuals.