Scientific name: Araneus diadematus
Other names: Garden Spider, Orb Spinner
There are about 600 species of spider in the British Isles, all of which are carnivores. The Garden or Orb Spider is the one which spins the large vertical web often highlighted by mists or morning dew. The female is bigger than the male, and with a larger abdomen in proportion to her body. Their colour can range from almost black to pale ginger, as with this specimen, and there is a characteristic pattern of white dots on the abdomen (opisthosoma) - usually in the form of a cross.
The typical arachnid four pairs of legs are relatively short compared to other species and they are covered with hairs or spines. They are attached to the front (prosoma) of the two sectioned body behind the mouth parts (chelicerae) and pedipalps which are used for holding prey and in the male, for holding the female when mating.
A female Garden Spider
They have six different types of silk glands or spinnerets located at the rear of the abdomen. Four of them produce different silks depending on purpose and the other two produce a sticky liquid to aid entrapment of the prey. The individual threads of silk are about 0.02 mm and have a similar strength to an equivalent strand of steel.
The spider waits in the centre or at the edge of the web until the vibration of the ensnared prey is picked up by sensors in its front pair of legs; it dashes to the prey and quickly wraps it in silk. Unable to comsume its food directly, the spider injects digestive juices into the immobilised creature via its mouth parts and sucks out the resulting liquid, leaving a crumpled mass of undigested pieces still wrapped in silk.
At mating time the male approaches the female carefully as it can easily be mistaken for food. The male has a pair of palps which pick up and store the sperm after it is secreted onto a special sperm-web. When a suitable mate is encountered the palps are inserted into the epigastric furrows on the abdomen of the female and the sperm is released, it is then stored in seminal receptacles until the eggs are layed. The male dies a short time later.
The female leaves her web and finds a suitable place - usually a crevice in bark or under a windowsill - to attach the egg cocoon which she makes from her silk as she lays the eggs. She remains close to the cocoon to repair any damage, but after a few days she too dies. The eggs undergo several stages of development before the larvae emerge and these change and grow through more stages before the small spiderlings appear. These quickly disperse as cannibalism is common in the confined space of the cocoon. They climb to an open perch and produce strands of silk which are caught by passing wind and they 'fly' away - known as ballooning.
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