Spiders
Araneae
Spiders have abdominal silk organs, male pedipalps modified into sperm transfer organs, and venom delivered through the chelicerae (secondarily lost in some spiders). Adult body size ranges from less than 1 to 100 mm. They are diverse and abundant worldwide with more than 50,000 described species.
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Whip Spiders
Amblypygi
Amblypygi are a nocturnal group of arachnids, commonly called whip spiders or tailless whip scorpions (not to be confused with spiders in the order Araneae or whip scorpions, also called vinegaroons, that belong to the related order Thelyphonida). The name "amblypygid" means "blunt tail", a reference to a lack of the flagellum that is otherwise seen in whip scorpions.
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Harvestmen
Opiliones
The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, or daddy longlegs. According to the most updated count, over 6,660 species of harvestmen have been discovered worldwide, although the total number of extant species may exceed 10,000.
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Pseudoscorpions
Pseudoscorpiones
Pseudoscorpions, occasionally known as false scorpions or book scorpions, are arachnids belonging to the order Pseudoscorpiones, sometimes known as Pseudoscorpionida or Chelonethida. Pseudoscorpions occur in all terrestrial environments from the seashore to the world’s highest peaks. They are generally rather small, with the largest reaching a body length of 1 cm.
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Mites & Ticks
Mites, including ticks, are traditionally grouped in a taxon called Acari. With more than 54,000 known species and an 10-20x this yet to be described, mites are the most diverse group of arachnids. Their fossil history goes back to at least the early Devonian period. Acarologists (people who study the Acari) have proposed a complex, and frequently changing, set of taxonomic ranks to classify mites.
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Scorpions
Scorpions are predatory arachnids of the order Scorpiones. They have eight legs and are easily recognized by the pair of grasping pedipalps and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger. Scorpions range in size from 9 mm / 0.3 in. to 23 cm / 9 in.
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Short-Tailed Whip Scorpions
Schizomida are commonly called short-tailed whip scorpions. There are over 200 species of schizomids in two families. These tiny arachnids – adults only between 5 mm – 1 cm – are found primarily in the tropics and subtropics but a few species have been reported from under ice and snow covered rocks. They are active, nocturnal predators that can move either forwards or backwards.
Hooded Tick-Spiders
There are between 50 – 60 species of hooded tick-spiders, all in one family (Ricinoididae). They occur in the rainforests of western and central Africa and in caves and forests from Texas to Peru. Fossil ricinuleids date back to the Carboniferous of Euramerica and the Cretaceous Burmese Amber.

The American Arachnological Society

The purpose of the American Arachnological Society is to further the study of Arachnids, foster closer cooperation and understanding between amateur and professional arachnologists, and to publish the Journal of Arachnology. It accomplishes this purpose in three main ways:

Meetings

The society hosts an annual meeting for professional and amateur arachnologists and students interested in arachnology to share research and ideas.

Supporting Graduate Studies

The society promotes undergraduate and graduate studies in arachnology by providing grants for travel to meetings and research, by recognition of high quality student presentations and posters at the annual meetings, and by providing information on graduate study opportunities in the field of arachnology.

Publications

The society publishes a refereed research journal, the Journal of Arachnology, three times a year. It also publishes the Spiders of North America-An Identification Manual, and has provided support for the publication of Common Spiders of North America.

News

2023 AAS Meeting - registration, abstract submission and applications for the AAS 2022 student travel awards open - American Arachnology #90 out now!

2023 American Arachnology Meetings Registration and Abstract Submission Now Open!

The annual meeting of the American Arachnology Society will be held…

Publishing organ