Mark Harvey, Curator of Arachnids, WAM
17 February 2021
Before telling us about spiders Mark began his presentation with some interesting facts about other local creepy crawlies. We learnt:
- Centipedes have only one pair of legs per body segment while millipedes have two pairs.
- A new species of millipede has been found in the Goldfields which has over a thousand legs.
- Scorpions tend to be nocturnal and show up greenish- yellow under UV light.
- Smaller scorpions (family Buthidae) have a more painful sting than larger species.
- Urodacus species live in spiral burrows which can be up to 2m deep.
- The entrance to Urodacus species’ burrows is elliptical c.f. circular for Trapdoor Spiders.
Mark then moved on to spiders by telling us that there are three major groups but only two, Mygalomorphae and Araneomorphae, are found in Australia. The third group, Mesothelae, are very primitive, ‘living fossils’, and live-in south-east Asia where Mark has had the pleasure of seeing Liphistius burrows while visiting Malaysia.
Also, during his general introduction, we learnt:
- Spiders have wide geographical distribution – from high altitudes to remote oceanic islands.
- They have a very long evolution, but even earliest species had fangs and venom.
- The fangs of spiders in the Mygalomorphae, such as trap door and funnel webs, operate vertically, while in the Araneomorphae, they act sideways.
- Spiders use their silk for many purposes including to capture prey and to make their shelter.
- A single female can spin up to 7 types of silk.
The third part of Mark’s presentation provided more details on specific spider families and genera. We were taken through many of the spiders we encounter in our houses, gardens or the bush; Tarantulas, Mouse Spiders, Red-backed Spiders, Daddy-long-legs, Wolf Spiders, Huntsman Spiders, Orb-weaving Spiders, White-tailed Spider, Black House Spiders, Crab Spiders, Bird-dropping Spiders, Triangular Spiders and finished with the Peacock Spiders.
Mark highlighted some of the myths about several of these species and added personal anecdotes of amusing enquiries and reports from the public. Trapdoor Spiders are closely related to Funnel Web Spiders, but there are no Funnel Web Spiders in Western Australia. Trapdoor Spiders are a very diverse group and can live for a long time (as many of us know, a giant spiny Trapdoor Spider, Gaius villosus, monitored by the late Barbara York Main died in 2018 after she had studied it for 43 years) but some Western Australian species are threatened, particularly those found in the wheat belt. It is possible that only the females of some species are left.
While the venom of the Red-back Spider is very toxic, it is slow acting, and fatalities are very rare. Similarly, the introduced Daddy-long-legs, has very poisonous venom, but because its fangs are so short, they cannot penetrate human skin. A few decades ago, White-tailed Spiders received a lot of attention in the press. However, they are not considered deadly although their bites have been known to cause necrosis, but this may be from bacteria living on the spider rather than from its venom. In conclusion, Mark reminded us how important spiders are as insect regulators.
While the audience couldn’t agree how long it was since Mark’s last presentation, there was unanimous agreement that he remains a raconteur par excellence.