Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Tuesday, February 05, 2008

Unusual creatures of the bush

We all know there are spiders in the bush. In the tall Eucalypt forest in East Kangaloon the webs of the leaf-curling spiders, and other spiders really do dominate the bush, as one tries to walk between the shrubbery of the area. The Leaf-curling Spiders form strong webs, in which they include a dried Eucalypt leaf, curled around to make a protective sheath. I seldom photograph these, as there is no chance of getting a good photo of the spider inside, and I figure everyone who knows the Aussie bush is familiar with these things. But the way they dominate the bush in high summer is something new to me. You can hardly walk any distance without having to break through webs, in this part of the tall Eucalypt forests of East Kangaloon.

Anyway, there was one striking Spider which I did manage to photograph the other day. This Spider had a near perfect web - in general terms, its overall shape is circular (known as an "orb"), with each panel adjusted at an appropriate angle, as it intersects each radiating line coming out from close to the centre. At the real centre of the web, where the spider waits, there is a small gap, with few of the fine "arc" lines (the web lines which make up the circular pattern of the main section of the web). Remarkably I managed to find an identity for it. It is Cyrtophora moluccensis, which tells me that this Spider's range extends to the Moluccas islands, in Indonesia, from where the "type specimen" was collected. In fact they range from India, to Japan and Australia.
Apparently the Spider may use a web for several weeks, repairing it as necessary, until she rebuilds it completely. This spider is very colourful. Web photos of this species show great variation between individuals, but the image linked here shows one with very similar markings to my specimen. The back of that specimen is nearly black, but the patterns on the side are virtually identical. Another internet site refers to these Spiders having a rusty red mark on the back of the abdomen - which fits my specimen nicely.

Here is a wonderfully bizarre Stick Insect
  • I had thought that it was the Tesselated Stick Insect  Ctenomorphodes tessulatus.
  • EDIT 13 Feb 2012: I have been contacted by Paul Brock, from the Natural History Museum of London, an internationally recognised expert on Phasmids. He has advised that the correct name for this insect is in fact Podacanthus wilkinsoniMany thanks for that Paul; I always welcome getting good advice on correct names. 
I was thrilled to find this specimen, as I have not seen one of these creatures, for many many years. It was about 12 centimetres (more than 6 inches) long. Its main feature is its wonderful camouflage. It has a habit of rocking back and forth slowly, seemingly to resemble a leaf, blowing in the wind.

This specimen had been damaged (lost its second and third leg on the left hand side), presumably as a result of an encounter with a predator. Similar injuries are reported in the discussion of the life cycle of these insects, on the Chew Family's wonderful website "Brisbane Insects and Spiders Home Page". The apparent ability to "lose a leg" is speculated on as a survival tactic, as a way of dealing with predator attacks.
This insect had very large "leaf-like" appendages on its rear. These are called "cerci", and apparently are tactile, sense organs. I had assumed that they were "claspers" as in Dragonflies, but apparently not. Indeed, you can see in this close-up photo, they do not have any clasping mechanisms, but look almost like flat "paddles".Stick Insects are generally creatures of the tree tops, and so we seldom see them. But apparently females descend to lower levels, presumably to lay their eggs. This one was clinging to the rough bark of a Eucalypt tree, at about one metre from the ground.
This is a top-down view of the head of the Stick Insect. You can clearly see its eyes. Its mouth is apparently designed for leaf-eating (it is not a carnivore). The antennae are not particularly long (compared to the large size of this insect). Male Stick Insects apparently have relatively long antennae, presumably to help them find mates. (Paul Brock says mine is a male.)

2 comments:

Anni said...

In other words I have been giving a whole lot of misinformation here ?

Denis Wilson said...

Hi Anni.
Don't feel bad - the natural history of Robertson had not been well researched at that time! I am working on it, as you know. Such a mistake would be unforgivable from now on. OK?

St Andrew's Cross Spider was illustrated on 19 January. One of these days I will learn to make hotlinks in the comments as you have done.

Your Spider was a really nice match with mine. It must be the local colour form. Nice to know mine was not a "one-off" specimen.

Cheers

Denis