Rainforest Revelations

Archive for January, 2008

The Bleeding Heart (Homalanthus novoguineensis) is the preferred food plant of the caterpillar (above), which attains a length of 12 cm and produces Australia’s largest moth: The Hercules (Coscinocera hercules).

The female moth has a slightly paler and larger wing area than the male (below), whose wingspan reaches up to 27 cms.

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This dominant 4.5metre male Estuarine Crocodile (Crocodylus porosus) resides a kilometre or so downstream from my own abode on Cooper Creek; a proximity that we never forget!

It has long been known that crocodile gender is determined by temperature. If the temperature of egg incubation is cool, around 30 degrees C, the hatchlings are all female. Warmer temperatures, around 34 degrees C, hatch all males. There is also strong population bias towards females; often as high as 10 to 1.

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Like most birds that I see at night, this Azure Kingfisher (Alcedo azurea) was roosting strategically on the distal end of isolated vegetation, to forecast the vibrations of predators.  In this instance, the climbing bamboo (Bambusa moreheadiana) provided safe harbour.

What was most unusual, though, was the sighting itself; being only my second of such a species in fourteen years of almost nightly scrutiny. The first, many years ago, was overhanging a section of Cooper Creek, where they are seen frequently throughout the day.   In this sighting, the bird was quite a distance up an officially un-named tributary feeder creek, but perfectly positioned for a photograph.

I find it very significant that such a beautifully conspicuous plumage can remain so well hidden over the years. As an individual species, how can its part in the natural landscape be understood and appreciated when it is so adept at concealment?   Its importance to other species and the interrelationships that define its ecological character are even less accessible.

The longer I persevere with my immersion into this ancient and secretive world, the more insurmountable its complexity becomes.  Very clearly, one lifetime will not be enough. I take a degree of comfort from the obvious advantage of my children, benefiting from the contribution of the knowledge that their parents and grandparents are able to impart, but additionally, from the knowledge that they gain from their own observations and interrelationships. With only three generations I can see the growing accumulation of intellectual property.

Just imagine the intellectual insight of two-thousand generations accrued by Australia’s indigenous people, the longest surviving human culture in the world.

These voracious, venomous predators of the night are seldom seen and even more infrequently in pairs, but what can be said of the affairs of the Scutigeromorph heart?

Well first of all, they have a series of trachea originating at dorsal openings that channel oxygen into the pericardium.   They also have a single dorsal heart which pumps oxygenated blood about the tissues of their relatively large and active architecture.

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Take a long look into the face of the world’s largest two-dimensional wheel-web weaving spider: The Golden Orb-weaver (Nephila pilipes).

The red appendages, projecting forward from the head region, are sensory organs called palps. They detect scent, sound and vibration. Between them are the powerful chelicerae; made up of the base segment and the fangs. Above, the cephalothorax houses six eyes with a three-dimensional outlook.

Gigantism in these animals correlates with increased temperature, so I suppose it is inevitable that we should all enjoy a closer familiarity in this anthropogenically-exacerbated interglacial warming period.