Saturday, June 25, 2011

Costa we come!

Hola! Our posts will come from Costa Rica over the next four months. We are about to embark on a trip to produce another series of the predatory bug TV program that we worked on last year and early this year. We will be spending a great deal of time looking through the rainforest for all sorts of invertebrates, and no doubt making many surprise encounters along the way. 

The invertebrate diversity is enormous in Costa Rica, as too is the wildlife diversity in generally, so hopefully we'll be able to regularly post some of the amazing encounters we have.

We'll be living and working on the edge of the rainforest on the Osa Peninsula; a peninsula on the southern (Pacific) side of Costa Rica. For the first 3 weeks we'll focussing on collecting invertebrates, and getting our sets prepared. We'll be setting up a small studio in a little town nearby and shooting the majority of the sequences in there.

Friday, June 24, 2011

More camouflage magic

This time the master of disguise is reptilian. This is a Leaf-tailed Gecko (Saltuarius cornutus) pictured in our backyard. They are the largest geckos in our region, growing to around 220mm in total length.

Like the Lichen Huntsmen in the previous post, these geckos have lichen-like patterns and colours all over their bodies and a rough outline to break up their shape, but they also have the ability to alter their shade of colour.

Also like the spiders, they sit head-down on rainforest trees both day and night, relying on their camouflage to conceal them. They feed at night upon tree dwelling invertebrates, a diet which most likely includes huntsman spiders. Occasionally they will leave the trees to find a mate or a new feeding territory, and I have occasionally encountered them crossing roads.

The remarkable eye of Saltuaris cornutus, complete with its own camouflage.

Wednesday, June 22, 2011

Masters of camouflage

I've just finished putting together a presentation about huntsman spiders for the upcoming Australian Invertebrates Conference in Melbourne. One of the species featured in the presentation is the Lichen Huntsman, Pandercetes gracilis. It is the sole member of the genus in Australia, and up close, a very spectacular animal. I needed a few extra photos for my presentation so I had a quick look in the yard and to my delight found 5 no more than 10 metres from the house.

These spiders sit on the tree trunks both day and night, unlike most other huntsman which hide by day to avoid predation. Pandercetes get away with it due to their superb camouflage. Their bodies are coloured and patterned to match the patchwork of lichens that occur on the tree trunks. They also have clusters of hairs on their legs which fan out and effectively break up their outline. To the untrained eye, they are almost impossible to see until they move.
These huntsmen are fast moving hunters, and in a blink of an eye they will have caught a passing insect.
There s a great deal of individual variation in the colour forms of this species. The five I photographed in the yard are all different. Some predominantly green, others shades of brown.

Wednesday, June 15, 2011

Velvet Assassins

In the last couple of weeks we have encountered several velvet worms (Onychophora); primitive predatory invertebrates which are though to have originated over 500 million years ago. They are believed to be the forerunners to arthropods, but unlike today's arthropods, the velvet worm has no hardened exoskeleton.

This velvet worm is about 30mm in length

Its skin is composed of a membrane of dead cells covered in tiny hairs, which are in themselves covered in tiny scales that give it the appearance and feeling of velvet. These hairs function in a sensory capacity and respond to touch. This covering is also water-repellent, which makes it perfect for living in a very moist environment – seconded by its inability to regulate water loss. It is therefore very easy for a velvet worm to succumb to desiccation, and as such, it is only found in tropical and temperate rainforests.

A close up of the face; a 'nozzle' for spurting the sticky liquid can be seen just beneath the eye.

One of the most remarkable things about this minute predator is its method of attack. It shoots twin streams of a sticky liquid at its prey from nozzles either side of its mouth. The liquid transforms to a bonding gel on contact with the prey as a chaotic mix of proteins within the substance combine and react. The result is dramatic, the prey is usually securely bonded to the surface it is on, and all the velvet worm needs to do is wander up and consume it at its leisure.  The one in the photo below actually shot glue on my finger when I first picked it up. I noticed an immediate chilling sensation as the liquid hit and reacted; I then spent a minute or so picking off all the sticky material!