An introduction to spiders

  • Updated
    04/04/22

Spiders belong to an ancient group of animals called the Arachnida.

Arachnids include scorpions, ticks and mites, harvestmen and false scorpions.

Spiders - Arachnida

Spiders belong to an ancient group of animals called the Arachnida. Arachnids include scorpions, ticks and mites, harvestmen and false scorpions. The primary source of food for spiders is, and probably always has been, insects. Arachnologists have calculated that every year spiders eat the weight of the whole human population in insects. It has been suggested that insects evolved the power of flight to get away from spiders. Of course spiders then developed new ways of catching them, such as spinning webs. The great diversity of spiders means that, wherever an insect goes - on the ground, under the ground, in the trees, or in the air - there is a spider that can catch it. There is even a rare spider that lives and hunts among rocks in the intertidal zone of Sydney Harbour foreshores.

  • Worldwide there are about 70,000 species of arachnids of which 36,000 are spiders.
  • Approximately 2,900 species of spiders are found in Australia.
  • Only a few species, including the Redback Spider and some funnel-web and mouse spider species, can inflict bites that are potentially fatal to humans.
  • One of the most dangerous of all is the Sydney Funnel-web Spider. There have been no fatalities from Sydney Funnel-web bites since the development of effective antivenom.

You can see spiders by day and especially by night in just about any habitat. The forests, woodlands and heathlands of our national parks (such as Royal National Park, Lane Cove River National Park, Kuringai Chase National Park) are good places to see a wide variety of species, but most gardens and parks will have a spider population. A night-time search of your backyard is a good place to start.