Main Club 9thApril 2021
Our speaker, Dr Mathew Hourston, describes himself as a marine scientist, photographer, communicator and citizen scientist. He has applied the skills that he developed in the study of marine ecology to the study of these amazing little spiders and their colourful courtship displays, which he does as a hobby rather than as a profession.
Peacock Spiders (mostly Maratus spp.) belong to the family Salticidae or Jumping Spiders. The genus is endemic to Australia. They are all characterised by having a hardened patch on the back of the abdomen called an opisthomal plate. Some have lateral flaps, some raise their abdomen in display, and some use their legs to “dance”. Like all jumping spiders, Peacock Spiders have eight eyes, good vision and depth perception. The males are colourful, but the females are mostly drab. They only live for a year and go through five moults. It is only after the last moult that the males acquire their bright colours. So, to find a male displaying, it is necessary to look during the period of the last moult, and when there is a female close by.
Mat says that identifying a species as a Maratus can be problematical because the classification is partly based on behavioural characteristics, so one has to wait until they display. Each species as its own pattern, dance, period of colour, habitat and geographic range. The number of species described has grown from ten species to more than 100 species in the last decade or so. It has been a “taxonomic goldrush”. Julianne Waldock has led this research in WA, and Joseph Schubert in Victoria. Jurgen Otto in NSW has popularised them with his videos of dancing spiders (see www.peacockspider.org).
The brilliant colours of Maratus species are only partly caused by pigments but have an element of “structural colour” made by microscale structures on the scales. Several species have “super black” patches, with only 0.5% of light reflected. Contrary to popular belief, the females don’t commonly eat the males. Rather, the females have their own dance meaning “not tonight, dear”, and the male has a response, which on the video looked remarkably like a sulk!
Mat talked about several Maratus species from around the South West. Many have a small geographic range, such as one that is probably restricted to two peaks in the Stirling Range. He said that Maratus speciosus, which he has videoed at Hillarys performing its “semaphore” display, is a relatively easy one to find. Look among the first row of plants in the coastal dunes, he said, on strappy plants such as Onion Grass, in the late afternoon of a windless, sunny day in September or October. Get low, stay still, and look for movement or colour. It is 5mm long. “Not in the heat of the day and look low.” (See YouTube video series Look Closer – Finding Peacock Spiders).
Much is yet to be learned about Peacock Spiders, such as how they cope with fire and how they can be conserved. But thanks to people like Mat Hourston, that knowledge is increasing, and the public is learning about these tiny but spectacular creatures.