Mount Gravatt Environment Group

Brushtail Possum

By: Michael Fox

At night in Mt Gravatt Conservation Reserve you see the bush with new eyes … and eyes are what you see.

I knew the eyes of many animals seem to glow in the light of a torch so I was not surprised to find the orange glow of a pair of eyes, was a Brushtail Possum Trichosurus vulpecula, prowling around.

What has been really surprising though are the dozens of sparkling lights on the ground – Wolf spiders Lycosa species. In torch light the eyes of these spiders look like tiny diamonds the reflection is so sharp. When I first saw this the light seemed to flash like Fireflies but that effect was just caused by movement of my torch as I approached. When I held the torch steady the light from the spiders’ eyes was also steady.

Garden Orb Weaver web

Apparently Wolf spiders are one a small number of spider species that have a layer of light reflecting crystals, tapetum lucidum, right behind the retina of the eye. This reflective layer improves night vision for these nocturnal hunters by bouncing light back to the retina.

It is interesting to see the different shape, colour and intensity of the light reflected by the eyes of different species. The Wolf spiders have small crystal clear light, while the Brushtail’s eyes were larger, wide apart and the reflection was softer. Toads have similar reflecting eyes and I am getting good at spotting them at a distance, keeping them sitting still in the light, then scooping them up in a plastic bag ready for freezing. I have removed ten toads from the Reserve from my last couple of night walks.

Garden Orb Weaver spiders, Eriophora transmarina, are another night time creature making huge webs at night which are cleaned up in the morning before they retreat to spend the day in a leaf shelter. This particular spider likes to make a web across the fire trail in the Fox Gully Bushcare site. The web spans an amazing 5 to 6 metres to bridge the trail. A large bug or something has already flown straight through this web so I ducked under to avoid any more damage to this extraordinary construction.