Sunday, March 27, 2011

Australian Lace-lid

I was very excited to find my second endangered frog for the week. I have been hoping to see this particular species, Nictimystes dayi, for a long time.

Like the Waterfall Frog, the Australian Lace-lid has declined in numbers over the past 30 years and is now reasonably rare. This species favours clean running rainforest streams, and seems to have suffered as a result of Chytrid Fungus. It is a very distinctive frog - the only Australian species to have an eyelid with distinct venation, hence the common name.

The Australian lace-lid, Nictimystes dayi

While I was photographing it, it suddenly closed its eyes to reveal the amazing lace-lids.

A close-up of the eyes with the lace-like patterns.

Baby snake

Deanna was given a tiny baby snake to identify while dropping Tayen off at kinda last week. She immediately identified the snake as a Brown Tree Snake, Boiga irregularis. The person who brought it in had found her daughter playing with it, and had since found 15 more of them around the house. The snakes had obviously just hatched, and were beginning to disperse.

Brown Tree Snakes belong to the family Colubridae; solid toothed and rear-fanged snakes. This particular species has rear-fangs and mild venom, and although they can be defensive at times, rarely do bites on humans cause envenomation. At this size they are quite harmless, and this little one was not the least bit aggressive.

We released the little snake in a tree on our front lawn. If it is lucky it will find food in the form of small skinks, geckos and frogs. If it survives to an adult it will graduate to small birds and mammals. Like all young animals in the wild, surviving this first period is the toughest. These snakes don't get any assistance from their parents, so from day one they are on their own.

The newly hatched snake on Deanna's hand

The snake resting under leaves in a tree. In the morning it had moved on.

The snake's key sensor; the tongue collects samples from the air and transfers them to a specialised organ on the roof of the mouth.

Saturday, March 26, 2011

Killer fungus

I spotted a spider recently at night; it lit up bright white in the torchlight and at first I was completely bewildered at which species I was looking at. It was in a normal hunting posture facing downwards on a tree but something was a little amiss. On closer inspection I found the entire spider engulfed in fungus. This is the third dead huntsman I have found here in the wet tropics in such a state - over taken by something their incredible leg speed can't outrun.

The fungus seems to attack them in such a way that they end up frozen in a normal posture.  A few years ago I observed a similar fungus in action infesting a small congregation of native bees that resided upon the leaves of a rainforest tree. The bees obviously returned to these same leaves regularly, but at some point the fungus would overtake them and they would remain and ultimately die. There were bees in various states of infection; some were dead and completely covered, and others had a partial covering or traces of the fungus. Some appeared healthy and free to come and go, oblivious to the slowly spreading threat nearby.

What appears to be a Brown Huntsman (Heteropoda jugulans) beneath its death shroud.

A close-up of the same fungus-covered spider.

The bees. A 'healthy' bee sitting in the foreground with infected and dead bees surrounding it. Some nearby leaves had more healthy bees with less fungal activity.

Wednesday, March 23, 2011

A rare encounter

This is a Waterfall Frog, Litoria nannotis, one of several species of frogs from upper rainforest streams that has suffered serious population declines over the last 20 years. One of the factors involved in the decline of these species is Chytrid Fungus.

This species lives in rainforests and wet sclerophyll forests near waterfalls and cascades. They will often sit upon boulders beside or behind waterfalls. I spotted this particular frog's eye shine with my head-torch. It was sitting beside water cascading down a large rock face. Females deposit their eggs under rocks in the stream bed, and their algae-eating tadpoles are well adapted to swimming in strong currents.

Litoria nannotis, the endangered Waterfall Frog

Friday, March 11, 2011

That's no ant

A small black ant appeared in our insect rearing room yesterday. Initially I didn't take any notice; after all small black ants are everywhere here. I did take notice however when it jumped and then began lowering itself down from the table on a line of silk.

There are many species of jumping spiders which mimic ants. This one (Myrmarachne sp.) appears to mimic the black Rattle Ants (Polyrhachis spp.) which are common rainforest residents. Whether it feeds on the ants, or just relies on the look for protection I'm not sure.

The spider’s body has evolved to look remarkably like an insect. This is certainly impressive since spiders only have two body parts and insects have three. The spider's cephalothorax (combined head and chest) has a distinct double-hump giving the illusion of a separated head and thorax. The abdomen is glossy and shaped like that of the ant it mimics. Dealing with the issue of an extra set of legs is easy - the spider simply holds them up, and waves them around like an ants antennae. The pedipalps (feelers) are held close to the face in the same position as the ant’s mandibles would be, completing the facade.

The cephalothorax has two peaks giving the impression that the segements are divided.
The front pair of legs are held up and waved around like the antennae of an ant.

Unlike ants, this spider still has eight eyes. Like typical jumping spiders, the two anterior median eyes are huge giving the spider excellent vision.
The spider's exoskeleton even has an ant-like sheen to it.

Thursday, March 10, 2011

Rainforest yabby

This is a young Orange-fingered Yabby (Cherax wasselli) which we found just out of the water beside our local rainforest stream. They are semi-aquatic and burrow along the water line of creeks and water bodies. There are number of very similar species throughout eastern Queensland, however the group has not been studied well.

Most aquatic crustaceans can leave the water for periods of time as long as their gills (under the tail) remain moist.