Unlike most other arachnids, harvestmen do not have a sucking stomach or a filtering mechanism. Although parthenogenetic species do occur, most harvestmen reproduce sexually. Currently, no fossil harvestmen are known from the Triassic. Some fossils from the Permian are possibly harvestmen, but these are not well preserved. The largest known harvestmen are gonyleptids. There have also been possible examples of harvestmen and daddy long-legs. The trident is a small group of (usually three) spines found in harvestmen exclusively. Some of these defenses have been attributed and restricted to specific groups of harvestmen. Cyphophthalmi differ from other harvestmen in a number of key ways. The Phalangiidae are a family of harvestmen with about 380 known species. Armored harvestmen in Laniatores can often use their modified morphology as weapons. In harvestmen, it may have the ornament of spines. Harvestmen (order Opiliones) also use autotomy as a first line of defense against predators. Eupnoi individuals, more specifically sclerosomatid harvestmen, commonly use this strategy in response to being captured. Harvestmen are well known for being chemically protected.