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Your World Heritage...

Spiders

Australia leads the world in its number of resident venomous spiders as well as the strength of their toxicity. However, of almost 9,800 species (only about 3,100 species are named) of spiders in 70 families throughout the country, most are perfectly harmless and interesting.

As with other animal types, spider diversity in the Wet Tropics is broad and many fascinating species occur here that range from the ominously large to the tiny and hardly noticed, from the dullest browns or black to the vibrantly hued or deceptively shaped.

 

Classifying spiders

Spiders can be roughly classified according the strategies they use for feeding. Spiders which appeared earlier in the evolutionary scale feed by waiting in a burrow for food to come along before grabbing it. Following them were spiders which actively wandered looking for food and which caught it by ambush or chasing it down. The evolution of flying insects generated an incentive for spiders to evolve new ways of catching food which couldn't be chased and so the earliest aerial web weavers arose.

The Wet Tropics spiders on these pages are discussed under primitive spiders, open range hunters, ambush predators and weavers.

 

Fascinating facts

Here are some fascinating, and sometimes gruesome facts, you may or may not know about spiders:

  • Most spiders feed on insects and other arthropods but some have larger prey. For instance, the whistling spider or bird-eating spider has been documented taking and feeding on frogs and small birds. The golden orb spider also regularly traps small birds in its strong web and usually kills them.
  • Spiders cannot eat solid food - they suck out their victim's body fluids and softer tissues using powerful stomach muscles.
  • A spider periodically sheds its skin (exoskeleton) so that it can grow (called moulting). Immature stages in between moults are called moults. Each species has a particular number of moults that it will go through before reaching its final adult stage.
  • The silk used to create webs or wrap up caught prey is made mostly of proteins and amino acids. There are at least seven different types of spider silk created for specific uses (such as web construction, anchor lines, wrapping prey and lining nests) and most spiders possess at least three types of spinnerets. These extensions at the end of their abdomen exude a liquid under pressure which becomes the threads, some of which may be very sticky.
  • Usually, once male spiders have mated, they no longer have any interest in eating and die shortly after. But, even in death, redback males often serve a purpose. The already engorged and gravid redback females always kill their suitors and, in most cases, also eat them. This provides them with a small reproductive advantage.

Allowing spiders to take up residence around dwellings can be beneficial in that they catch other annoying insects such as mosquitos and flies. If you find a spider in your home that you don't want there, you can use a large drinking glass to trap it by gently placing the open glass over the spider as it sits on a wall or flat surface; slide a sheet of paper under the rim so that the spider is trapped inside when you move the glass. Take it outside and toss it into a shrub or let it escape onto a tree trunk. Avoid using insecticides to kill spiders as these chemicals also kill other animals like frogs.

Rest assured that while you might see some large spiders, and perhaps even some venomous ones, none will actually behave like the Australian spider, Delena cancerides, when wrongly portrayed as a dangerous villain in the horror film Arachnophobia!

A good rule of thumb is to look and admire but don't touch any spider you find. Even those without venom could still have a nasty bite.

After you've had a read through our spider profiles pages, you can visit some of the museum web sites around Australia. Here are a few handy links:

 

News and Events

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News and Events

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