Pisaura mirabilis

Nursery web spider
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Arachnida
Order:	Araneae
Family:	Pisauridae
Genus:	Pisaura
Species:	P. mirabilis
Binomial name
Pisaura mirabilis (Clerck, 1757)

The nursery web spider Pisaura mirabilis is a spider species of the family Pisauridae.

It was described in chapter 5 of the book Svenska Spindlar by the Swedish arachnologist and entomologist Carl Alexander Clerck.

Striking characteristics of the Pisaura mirabilis are its long legs (the fourth one being the longest) and its slender abdomen (opisthosoma). The male is between 10–13 mm, while the female is 12–15 mm. After final ecdysis the male spiders weigh on average 54 mg and females 68 mg.

The prosoma is variable in color, ranging from light to reddish brown and from gray to black. A lighter stripe is visible down the middle of the prosoma. The opisthosoma is long and narrow and tapered towards the rear end.

Female spiders have a dark patch (epigyne) on the underside of their abdomen that includes the copulatory organs. Male genital openings can be found at the same location, but remain inconspicuous.

Patterning and coloration varies due to polymorphism. These patterns, which can be caused by hair and pigments, change with the growth of the spider (ontogenesis).

Male spiders are stronger in contrast than females and look black, especially in comparison to the white nuptial gifts. Females tend to get paler towards the end of summer. The stripe along the back of the body can be found in all spiders and can be seen as crypsis, a protective measure against predators.

The pedipalps in nymphs and females look similar to legs. In males, this structure gets thicker towards the end and is used to store sperm until reproduction (bulbus). The outer chelicerae segment consists of three teeth. They catch their prey during the day and at night and are also active on warm winter days.

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Wikipedia