If critters with lots of legs make your skin crawl, the video that Lake Clark National Park and Preserve posted to their Facebook page on Halloween probably looked like a nightmare come alive. In the 45-second clip, a silent camper shines their light around the interior of their tent; through the translucent fabric, you can see hundreds of spider-like creatures crawling across the exterior and gathering in huge clumps. Also known as daddy longlegs, harvestmen are members of a group of arachnids called Opiliones, which are related to but distinct from their better-known eight-legged relatives...