Tube web spider; cellar spider

This spider was brought in to the museum after it bit a member of the public on the ankle in his sleep. At just under 2 cm long this is only a juvenile female tube-web spider (Segestria florentina); the patterning on her grey abdomen indicates she is not yet mature as usually adults of both sexes are almost entirely black. Adult females are among the largest spiders found in England. As the name suggests these spiders make a tube-shaped web often in tree bark or holes in walls. The web has lines of silk radiating out from the edge that will alert the spider to the presence of small moving prey - wasps and flies are a particular favourite. When the prey triggers the trip wire the spider will dash out of the tube and capture the tasty snack with its large chelicerae (fangs). If you look closely at the chelicerae you will notice that each has a stunning stripe of iridescent green down its length. Fancy meeting this green-fanged fiend? If so have a look in the south-facing outer walls of Exeter Cathedral. These spiders have found the perfect home in cracks and crevices where the limestone has been worn away but weathering and acidic pollution. This tube web spider is native to western continental Europe and was introduced to Britain via ships and seaports to towns such as Exeter, Bristol and Dover about 150 years ago and are gradually spreading inland. In some walls they are so abundant that every hole is plugged with spider in its silken web. Unlike our native tube web spiders S. florentina much prefers to live in human constructions. Yet it is normally secretive and nocturnal and it will be easily frightened by human presence. However, if accidentally disturbed it will give a nasty nip that can cause pain and swelling for several hours or days.