Harvestman, Leiobunum sp., in McCurtain County, Oklahoma. Harvestmen are also known in America as daddy longlegs. Although frequently confused with spiders, they belong to a different arachnid order, the Opiliones. Unlike spiders, opiliones have a broad attachment of the cephalothorax to the abdomen so their body appears as a single unit. Additionally, they have no silk or venom glands. It is thought that there many be close to 10,000 species.