Nursery-web spider  (Pisaura mirabilis)

Female nursery-web spider
Female nursery-web spider
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Facts

Kingdom Animalia
Phylum Arthropoda
Class Arachnida
Order Araneae
Family Pisauridae
Genus Pisaura(1)
Size Male length: 10-13 mm (2)
Female length: 12-15 mm (2)
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Status

This widespread species is not threatened. It is not listed under any conservation designations (3).

Description

This spider is the only member of the Pisaura genus in Britain (2). The abdomen is slender and tapering and there is a light stripe along the middle of the carapace. The colour is variable, and may be grey, yellowish-orange or dark brown. Although males are generally similar in appearance to females, they tend to be darker, with more noticeable markings (2) and have smaller abdomens (3).

Range

This spider is common and widespread throughout Britain, but is scarce in Scotland (4). It is also found in northern Europe (3).

Display NBN Map ButtonYou can view distribution information for this species at the National Biodiversity Network Gateway.

Habitat

Found in woodland clearings, grassland and heathland (3) in long grass, shrubs or amongst hedgerows (2).

Biology

Members of this family of spiders are active hunters with good vision (3). The nursery-web spider hunts amongst low vegetation as well as on the ground. When detecting prey, they characteristically rest on vegetation with the first two pairs of legs together, held out at an angle (3).

During courtship, males present females with a ‘nuptial gift’ in the form of an insect wrapped in silk (3). Until fairly recently, this gift was thought to protect the male from becoming the female’s next meal. Research has shown, however, that the gift entices the female to mate, and what’s more, the size of the gift is related to how long the female will mate with a male. The larger the gift, the longer copulation will last and so more eggs will be fertilised by more ‘generous’ males bringing larger gifts (4).

Female spiders belonging to this family produce very large egg sacs, which they carry around beneath their body. When the time for the spiderlings to emerge approaches, the female deposits the egg sac on a leaf and spins a protective silk ‘nursery web’ around it. She then opens the egg sac slightly, and stands guard until the spiderlings emerge (3).

Threats

This species is not threatened

Conservation

Conservation action has not been targeted at this widespread species.

Find out more

For more on this species see:
Roberts, M.J. (1995) Spiders of Britain and northern Europe. Harper Collins Publishers Ltd, London.

For more on British spiders see The British Arachnological Society:
http://www.britishspiders.org.uk/

Authentication

Information authenticated by Dr Peter Merrett of the British Arachnological Society:
http://www.britishspiders.org.uk/index.html

Glossary

Abdomen: in arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (e.g. crabs) some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen. In vertebrates the abdomen is the part of the body that contains the internal organs (except the heart and lungs).
Carapace: the top shell of a turtle. In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head) also known as ‘cephalothorax’.
Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

References

  1. National Biodiversity Network Species Dictionary (September 2003)
    http://www.nhm.ac.uk/nbn
  2. Roberts, M.J. (1993) The spiders of Great Britain and Ireland Part 1- text. Harley Books, Colchester.
  3. Roberts, M.J. (1995) Spiders of Britain and northern Europe. Harper Collins Publishers Ltd. London.
  4. Merrett, P. (February 2004) Pers. comm.
  5. Stalhandske, P. (2001) Nuptial gift in the spider Pisaura mirabilis maintained by sexual selection. Behavioural Ecology 12: 691-697.
    http://beheco.oupjournals.org/cgi/content/abstract/12/6/691