Argiope keyserlingi

Here is a spider most people in Sydney will recognise, the St Andrews cross (Family: Araneidae, Genus: Argiope). 

The female is very distinctive with yellow stripes on her abdomen and a cross in the middle of her web, so I assumed this ID would be simple.

But then I came across these two. 

At first glance I assumed they belonged to another, smaller species of Argiope (there are a number of Argiope species in Australia) because they didn't have any stripes.

But on closer inspection (and a little help from: www.arachne.org.au) I found out that this is a juvenile male (left) and female. 

Just goes to show how careful you have to be not to make assumptions! I have a few other revelations like this one that I'll post over the next few weeks :)

Here are a few more photos of Argiope in action (they do look a lot nicer when they haven't been in ethanol for a few months like the ones above!)

Female and smaller brown male

Female with a very nicely made cross