The Red-back Spider is probably the most well known and feared spider in Australia and it belongs to the Family Theridiidae. The Red-back also belongs to the same species as the New Zealand's Kapito and America's Black Widow spider (minus the red stripe).
Red-back spiders are easily recognised by the red markings on their pea-shaped abdomens The male Red-backs are significantly smaller than the female Redbacks and have tiny fangs which can't penetrate the skin. In fact the male Redback spiders are often mistaken for baby spiders because they are so small, approximately 3mm long, where as the female Red-back is approximately 14mm.
Gum-Footed Tangle Web
The Red-back tends to gravitate to urban habitats where lights, shelter and food scraps attract their potential prey and are often found in sheds, letterboxes, window sills or under the toilet seat in outhouses. The home of the Red-back is a complicated, yet clever, web system known as a Gum-footed Tangle Web. The spider lives in a funnel-shaped retreat (tangle web) above what is known as a "gum-footed snare". This is one spider we should be grateful it can only grow to 14mm! The spider hangs upside down above the snare, waiting and watching for its prey to walk into it's trap. The snare or trap is made from sticky trap lines. A series of vertical sticky threads run down from the tangle web to the ground. Each vertical line is made up of four dry supporting lines all covered in a sticky substance. The lines are lightly attatched to the ground. The support lines, which are held taut, provide strength. When a insect inadvertantly walks into the threads and begins the struggle to break free, the lines which are weakly attached to the ground, break loose, sending the now unattached lines and the insect upwards. The spider know has a suspended victim, which it pulls up to inflict it's deadly bite.
Food and Predators
The main food source for these spiders are flies, moths, mosquitoes, roaches and the occassional trapdoor or Funnel-web spider . Interestingly, it's the spindly Daddy Long-leg Spider who is a the spider's major predator (another cannibal). Redbacks have also been known to lunch on small lizards if they happen to get caught in their trap.
Friend or Foe ?
Foe ! Fortunately it is only the female Redback spiders which are dangerous to humans. The male Redbacks are significantly smaller than the female Redbacks and have tiny fangs which can't penetrate the skin. The female's venom is extremely toxic but because she only has very small fangs the quantity of venom in a bite is quite small. Most Redback spider bites occur during the summer months, when people and the Redbackss are active out in the garden. Redbacks very rarely wander from their web, so the most common way for people to get bitten, is by disturbing the spider's habitat. So whatever you do don't try patting them ! If you are working in the garden or yard it is recommended you wear gloves, especilly if you are moving things. The general symptoms of a Redback bite is pain, sweating, muscular weakness and nausea. If bitten by a female Redback it is important to seek medical help, as the venom, though rarely fatal, attacks the nervous system. Apply an ice pack to the bite area to reduce the pain and get yourself to the doctor or a hospital. All major hospitals in Australia carry antivenom.
Facts About The Red-back Spider
Female Redbacks are known to steal food from other spider's webs.
It is the female who is responsible for building the web, the male spider plays no part in construction.