Purse-web spider (Atypus affinis)
| Kingdom | Animalia |
|---|---|
| Phylum | Arthropoda |
| Class | Arachnida |
| Order | Araneae |
| Family | Atypidae |
| Genus | Atypus (1) |
| Size | Male length: 7-9 mm (2) Female length: 10-15 mm (2) |
This widespread species is not threatened. It is not listed under any conservation designations (3).
This spider belongs to the same suborder (Orthognatha) as tarantulas, funnel web spiders and trap-door spiders. Just one genus belonging to the family Atypidae is found in Britain, and it is represented by this species alone (2). The name of the suborder Orthognatha means ‘straight jawed’. This name refers to the chelicerae, a pair of appendages on the ‘head’ of the spider which are used to kill prey. In this suborder, the chelicerae project forwards from the carapace(2). This species is easy to identify, it has a squarish carapace and large, stout chelicerae, and the legs are stocky (3). Males are similar in appearance to females, but have longer legs and a thinner abdomen(2).
This spider is found mainly in southern England, but has been found in Scotland and Wales (2). In Europe this species has a wide range, reaching as far north as Denmark (3).
Inhabits rough grassland and heathland (2) on sandy or chalky soils (3).
The web of this spider is more like a sock than a purse. The web forms a tube, part of which lines a burrow; the remainder lies along the surface of the ground, disguised with soil particles (3). When insects land on this tube, the spider grabs them with its fangs and drags them inside where they are eaten. The remains of the meal are later thrown out of the tube and the hole is repaired (2). The spider spends most of its life inside this tube; only young spiderlings and males in search of females actively wander (3).
Mating occurs in autumn. When a male finds a burrow occupied by a female he will tap on the silk tube. If the female is receptive, she allows the male to enter the burrow where they mate. They live together in the female’s burrow for a time until the male dies. The female eats the male, and the nutrients contained within his body contribute to the developing eggs. The female produces an egg sac which she suspends within the tube. The eggs hatch the next summer but the young spiders will not disperse until the spring of the following year. It takes around 4 years for individuals to reach sexual maturity. Males die following mating, but the females live for several years more (3).
This species is not threatened.
Conservation action has not been targeted at this widespread species.
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/
Information authenticated by Dr Peter Merrett of the British Arachnological Society:
http://www.britishspiders.org.uk/index.html
- 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’.
- Chelicerae: pair of appendages on the ‘head’ of an arachnid (spiders, scorpions, mites, harvestmen etc). In spiders and harvestmen these appendages are jointed and are used to kill prey, and in defence. In spiders there is a poison gland at the base of each chelicera, from where a duct leads to the tip of the fang.
- 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.
- National Biodiversity Network Species Dictionary (September 2003) http://www.nhm.ac.uk/nbn/
- Roberts, M.J. (1993) The spiders of Great Britain and Ireland Part 1- text. Harley Books, Colchester.
- Roberts, M.J. (1995) Spiders of Britain and northern Europe. Harper Collins Publishers Ltd. London.