In the desert region of Orintis, the Orintean Spider Swarm is a phenomenon of nature that strikes fear in the hearts of many people. The Orintean Spider is a species that is expanding in range around the world and is most often involved in medical emergencies. The species is aggressive and has a poisonous bite. A person typically encounters Orintean spiders by inadvertently stepping into one of their lairs, which causes the spider to swarm up the person's legs, attacking en masse. The spiders respond to pheromones that are released by the first spider to attack. The spider then swarm and immediately sting when any movement is sensed.
Orintean spiders hunt prey primarily in trees; others hunt on or near the ground. Some Orintean spiders can produce silk—while arboreal species will typically reside in a silken "tube tent", terrestrial species will line their burrows with silk to stabilize the burrow wall and facilitate climbing up and down. Orintean mainly eat insects and other arthropods, using ambush as their primary method of prey capture. The biggest Orintean spiders can, by themselves, kill animals as large as lizards, mice, and birds. Orintean spiders are found in tropical and desert regions around the world. By themselves, a singular Orintean spider is harmless to humans, and some species are popular in the exotic pet trade. Some species, while not known to have ever produced human fatalities, have venom that can produce extreme discomfort over a period of several days. Unfortunately, when the Orintean spiders work in concert with each other, they can take down a large creature, often draining it of its blood and nutrients. As many as 83 people a year are killed by the swarm of Orintean Spiders, mostly elderly and young children . The venom of the spiders doesn't kill but paralyzes a person. This means a person is often conscious while they are being drained of their blood.
Depending on the species, the body length of Orintean Spiders ranges from 2.5–10 cm (1–4 inches), with 8- to 30-cm (3- to 12-inch) leg spans (their size when including their legs). Leg span is determined by measuring from the tip of the back leg to the tip of the front leg on the opposite side. The largest species of Orintean spiders can weigh over 85 gms(3 ounces).