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The class Arachnida is made up of spiders, scorpions, ticks, mites, solifuges and harvestmen[2]. While most arachnid species are terrestrial, some are wetland dependent, or even inhabit marine and freshwater environments.


Quick facts

Water mites
are quite distinct from spiders. Their cephalothorax and abdomen are completely fused while spider bodies are divided into two parts—the head/thorax (cephalothorax) and abdomen[1].


Arachnids have eight legs and fused body segments. This phylum includes spiders and mites. Spiders have two main segments, a cephalothorax and an abdomen. They are predatory animals which are mobile hunters or web-spinners. Some spiders live in wetland habitats, hunting by the waters edge or surface. Mites have a single fused body segment. They can be free-moving, but many species live as parasites on plants and animals. Aquatic mites, although a major component in benthic and hyporheic communities, can often be overlooked or left unidentified due to their small size.

Additional information

Australian freshwater invertebrates

Atlas of Living Australia


  1. ^ Murray Darling Freshwater Research Centre. Acarina / Acari (mites). [online] Available at: [Accessed 24 February 2016].
  2. ^ Cracraft, J & Donoghue, MJ (2004), 'Assembling the Tree of Life: Where We Stand at the Beginning of the 21st Century', in J Cracraft (ed.), Assembling the Tree of Life, Oxford University Press, Oxford, pp. 553-561.

Last updated: 12 April 2017

This page should be cited as:

Department of Environment, Science and Innovation, Queensland (2017) Arachnida, WetlandInfo website, accessed 18 March 2024. Available at:

Queensland Government
WetlandInfo   —   Department of Environment, Science and Innovation