Autumn in Japan is a time when we can see orb spiders everywhere in parks busy weaving their orb webs. Orb webs are the classic structure with concentric circles joined by radiating spokes.
Orb spiders are just one group among the many species of spiders. Other kinds of spiders weave tangled webs or jump on their prey. By the way, spiders don’t hunt or attach in groups, so the scene in Harry Potter with the swarms of spiders in the cave isn’t accurate.
Spiders have a huge impact as predators on insect populations (along with birds with bats).
Scientists have found from recent studies of amber specimens that orb spiders evolved much earlier than thought. Spider genetics suggests that orb spiders evolved as early as 136 million years ago during the Cretaceous period. Previously, it was thought that the orb design was an adaptive design that evolved later, but recent studies confirm that not only is this type of orb web design very old, but that it was later lost in certain lineages of spiders. Source: “Amber-preserved web shows early spider evolution” by Maggie Fox, Reuters