Spiderlings are cannibalistic, more active ones sometimes eating their less active siblings. They also consume sticky silk as well as small midges and flies. Baby spiders also steal food from their mother, which she tries to prevent. If a male redback is accepted by a female, it is permitted to feed on the victims snared in the female's web. When they encounter other spiders of the same species, often including those of the opposite sex, they engage in battle, and the defeated spider is eaten. Redback spiders do not usually drink, except when starved.Ĭommonly, prey-stealing occurs where larger females take food items stored in other spiders' webs. Once it has trussed the prey, the redback takes it to its retreat and begins sucking out the liquefied insides, generally 5 to 20 minutes after first attacking it. Unlike other spiders, it does not rotate its prey while wrapping in silk, but like other spiders, it then injects a venom that liquefies its victim's innards. It then bites its victim repeatedly on the head, body and leg joints and wraps it in sticky and dry silk. Once alerted to a creature becoming ensnared in a trap line, the redback advances to around a leg's length from its target, touching it and squirting a liquid glutinous silk over it to immobilise it. Food scraps and lighting attract insect prey to areas of human activity, which brings the redbacks. Developing spiderlings need size-appropriate prey, and laboratory studies show that they are willing to consume common fruit flies, mealworm larvae, muscoid flies and early nymphs of cockroaches. The woodlouse is a particularly common food item. One web was recorded as containing a dead mouse. Redbacks usually prey on insects, but can capture larger animals that become entangled in the web, including trapdoor spiders, small lizards, and even on rare occasion snakes. The female spends more time in the funnel and less time moving around during cooler weather.įemale with a lizard it has captured Prey These webs are usually placed between two flat surfaces, one beneath the other. They also snare and haul prey into the air when weaker horizontal strands that hold them down, known as guy lines, break when prey thrash around. The vertical strands act as trip wires to initially alert the spider to the presence of prey or threats. This area has vertical, sticky catching threads that run to ground attachments. The rear portion of the web forms a funnel-like retreat area where the spider and egg sacs are found. Although the threads seem random, they are strategically placed for support and entrapment of prey. Classified as a gum-footed tangle web, the web is an irregular-looking tangle of fine but strong silk. The redback is mainly nocturnal the female remains concealed during the day, and spins her web during the night, usually remaining in the same location for most of her adult life. Small compared to the female, the male redback is 3–4 mm (0.12–0.16 in) long and is light brown, with white markings on the upper side of the abdomen and a pale hourglass marking on the underside. Each spider has a pair of venom glands, one attached to each of its chelicerae with very small fangs. The bright scarlet red colours may serve as a warning to potential predators. Juvenile females have additional white markings on the abdomen. Redback spiderlings are grey with dark spots, and become darker with each moult. The cephalothorax is much smaller than the abdomen, and is black. Females with incomplete markings or all-black abdomens occasionally occur. The round abdomen is a deep black (occasionally brownish), with a red (sometimes orange) longitudinal stripe on the upper surface and an hourglass-shaped scarlet streak on the underside. The adult female redback has a body around 1 centimetre (0.4 in) long, with slender legs, the first pair of which are longer than the rest. A juvenile female, showing typical white banding
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