The Opiliones are an order of arachnids colloquially known as harvestmen, harvesters. Since the 1990s, study of the biology and ecology of harvestmen has. Up ^ Kury, Adriano B. 'Classification of Opiliones'. Jump up to: Machado, G., Carrera, P.C., Pomini, A.M., Marsaioli, A.J., 2005. A phylogenetic classification of jumping spiders (Araneae: Salticidae) A Protocol For Digesting Internal Soft Tissues And Mounting Spiders For Scanning Electron Microscopy THE NEGLECTED COUSINS: WHAT DO WE KNOW ABOUT THE SMALLER ARACHNID ORDERS?
Recent A male, showing the long legs Kingdom: Phylum: Class: Subclass: Order: Opiliones, 1833 Suborders • • • • Diversity 4 suborders, > 6,500 species Opiliones (formerly Phalangida) are an order of commonly known as harvestmen. As of December 2011, over 6,500 species of harvestmen have been discovered worldwide, although the real number of species may exceed 10,000. The order Opiliones can be divided into four suborders:,,. Well-preserved fossils have been found in the 400-million-year-old of Scotland, which look surprisingly modern, indicating that the basic structure of the harvestmen has not changed much since then. Phylogenetic position is disputed: their closest relatives may be the mites () or the (the, and ). Although they belong to the class of, harvestmen are not, which are of the order rather than the order Opiliones. In some places, harvestmen are known by the name ' daddy longlegs' or ' granddaddy longlegs', but this name is also used for two other unrelated arthropods: the (Tipulidae) and the (Pholcidae).
Tropical harvestman These arachnids are known for their exceptionally long walking legs, compared to body size, although there are also short-legged species. The difference between harvestmen and spiders is that in harvestmen the two main body sections (the with ten segments and, or prosoma and ) are broadly joined, so that they appear to be one structure; they also have no or silk glands. In more advanced species, the first five abdominal segments are often fused into a shield called the, which is normally fused with the. Sometimes this shield is only present in males. The two most posterior abdominal segments can be reduced or separated in the middle on the surface to form two plates lying next to each other. The second pair of legs are longer than the others and work as.
This can be hard to see in short-legged species. The feeding apparatus () differs from other arachnids in that ingestion is not restricted to liquid, but chunks of solid food can be taken in. The stomotheca is formed by extensions from the and the first pair of legs.
They have a single pair of eyes in the middle of their heads, oriented sideways. However, there are eyeless species, such as the Brazilian () from nests, () from caves, and all species of. A harvestman (a male Phalangium opilio), showing the almost fused arrangement of abdomen and cephalothorax that distinguishes these arachnids from. Harvestmen have a pair of prosomatic defensive () that secrete a peculiar smelling fluid when disturbed, confirmed in some species to contain noxious. Harvestmen do not have and do not possess, posing absolutely no danger to humans (). They do not have, and breathe through only.
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