Scorpions belong to the arachnid group (invertebrates with four pairs of legs and two body parts) along with such animals as spiders, ticks and mites. They are distinguished from other arachnids because they possess a large pair of pincers and a tail with a venomous sting on the tip. They are a very primitive group that has existed with the same basic body plan for some 450 million years.
Scorpion, Urodacus sp.
Photographer: Alan Henderson. Source: Museum Victoria
Some of the interesting biological features of scorpions include:
- nocturnal activity, external digestion of their food (generally other invertebrates)
- a mating dance during which the male deposits a packet of sperm on the ground and guides the female over it to be picked up
- birth of live young that spend their early life on the back of the mother
- relatively slow rates of development (scorpions can live for quite a long time) and
- low metabolic rates.
This latter factor is one of the reasons why scorpions have survived for such a long time – they spend most of their lives resting under rocks, pieces of wood, or in burrows and expend very little energy. This results is the need for only occasional meals.
World-wide there are 1500 known species of scorpions. Australia has about 80 species (although many have yet to be named scientifically), and Victoria has nine known species. They are widely distributed. Many people are under the impression that scorpions are desert creatures, but although there are many more species in the drier parts of Australia, scorpions are found in quite cool and wet regions of Australia.
Scorpions are often feared because of the sting on their tail and the potential lethal nature of the venom. Several thousand people die each year from scorpion stings, but these deaths are from the stings of about 25 species that inhabit northern Africa, the Middle East, India, Mexico and parts of South America. None of these potentially lethal species occur in Australia. The Australian species can inflict a painful sting that results in swelling and pain for several hours, but there have not been any confirmed deaths of people from stings from Australian scorpions. Medical advice should be sought if you are stung by a scorpion.
A Scorpion sting (SEM)
Photographer: Dr Ken Walker / Source: Museum Victoria
Further Reading
Walker, K. L., Yen, A. L. and Milledge, G. A. 2003. Spiders and Scorpions commonly found in Victoria. Royal Society of Victoria: Melbourne.