Certainly the most recognizable of all arachnids, spiders are ubiquitous little predators on every continent except Antarctica. Their lineage stretches back 380 million years, with some of the oldest known fossils such as Attercopus fimbriunguis dating from the Devonian period and still having segmented abdomens.
Pre-Devonian in origin, the Pseudoscorpiones are one of the oldest extant lineages and over the past 392 Ma have diverged into more than 3400 known species in 26 families. Most are less than five millimetres in length, though they range from less than one millimetre in some Chthoniidae to just over ten millimetres in females of Garypus titanius Beier, 1961. They superficially resemble true scorpions, but lack the elongated tail and sting.
The 11 orders of Arachnids
The class Arachnida contains some of the most fascinating and enigmatic arthropods on earth, many of which are completely unknown to the general public. To remedy this, this article provides information covering each of the 11 different groups or orders of arachnids.
Hitchhiking is a time-honoured tradition for many a backpacker, and is an inexpensive way of covering the distance between destinations. Nature, of course, has its own version called phoresis or phorecy. In this case a phoront (the hitchhiker) attaches itself to a host and travels along until said host reaches a suitable destination, where the phoront will then detach again.
Pseudoscorpions have mastered this art to the extent that some species even require phoresis to survive. Pseudoscorpions themselves are an ancient order of tiny predatory arachnids, usually no more than 3mm in size, that superficially resemble true scorpions but lack the elongated tail and sting. Many species possess venom which they can inject into prey from small venom teeth at the ends of their pincers. This makes the Pseudoscorpiones one of only three arachnid orders that possess venom, the other two being true spiders (Araneae) and true scorpions (Scorpiones). Pseudoscorpions occur in almost every part of the world, though most species are found within the tropics and subtropics.
Arachnology is the scientific study of spiders and their kin, with particular emphasis on the identification of new species, the study of their biology and how they interact with their environment. Humans have had a fascination with these organisms since ancient times, with many early societies having myths with prominent spider figures.