Purse Web Spider

Purse-web spiders are the only known host of Aporus unicolor, a wasp which has a specialized foreleg for breaking into Purse-webs' webs. This wasp stings and paralyzes the web's inhabitant, laying an egg on it. The larvae then use the spider as food while they develop. Purse-web spiders are also prey to some other spider species, as well as birds and small mammals.

Known Predators:

• Aporus unicolor (Family Pompilidae, Class Insecta)

Purse-web spiders are mygalomorphs (fangs point straight downward vs. crossing each other) with two pairs of book lungs and posterior spinnerets with three segments. This spinneret morphology distinguishes it from the closely related Atypus muralis, whose spinners have four segments. Their bodies are light olive-green in color with brown, oval shaped scutums. Purse-web spiders have eight legs and two main body segments, the cephalothorax and abdomen. Their legs are stocky and they have stout chelicerae projecting from square carapaces. The base of each chelicera contains a venom gland with a duct leading to the tip of the fang. Males average 7-9 mm in length and have thinner abdomens and longer legs than females, which tend to be larger, averaging 10-15 mm in length.

Range length: 7 to 15 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; venomous

Sexual Dimorphism: female larger; sexes shaped differently

Lifespan of female purse-web spiders is estimated to be approximately 8 years, with some living up to 10 years. Males often have shorter lifespans because they do not survive mating, which occurs as early as 4 years of age. There is no data available regarding the lifespan of this species in captivity.

Typical lifespan
Status: wild: 4 to 10 years.

Average lifespan
Status: wild: 8 years.

Purse-web spiders are found in a variety of different European habitats. Most individuals are found in dry, sparse woodlands, calcareous grasslands and heathlands, but the species is also found in sand dunes and rocks, screes, cliff, or quarry habitats. This species most commonly uses areas with sparse, vegetative ground cover. They dig vertical burrows that can be up to 90 cm deep, depending on soil conditions.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; scrub forest

Purse-web spiders are distributed throughout southern England and can also be found throughout the British Isles. They are also common on the Iberian peninsula and can be found as far north as Denmark and Sweeden and as far south as Northern Africa.

Biogeographic Regions: palearctic (Native )

This species is known to feed on beetles (Coleoptera), earwigs (Dermaptera), flies (Diptera), woodlice (Isopoda), and bees (Hymenoptera), relying on their webs to capture prey. Webs are disguised with soil particles on the surface of the ground and, when prey lands on them, spiders capture and kill the prey with their fangs and associated venom. The prey is then brought into the burrow and fed upon. Prey remains are thrown out of the tube.

Animal Foods: insects

Primary Diet: carnivore (Insectivore )

There is no specific data available regarding the communication methods used by Purse-web spiders. However, in general, web spiders often emit species-specific vibrational signals during courtship, which identify males. In spiders, the most common mechanoreceptors, used to perceive vibrations, are hair sensillum. All species of Atypus have eight eyes, which can be used to visually perceive their environment.

Communication Channels: tactile

Other Communication Modes: vibrations

Perception Channels: visual ; tactile ; vibrations

This species has not been targeted by most conservation groups, although it has been suggested that humans may adversely affect populations by trampling areas in which colonies have dug burrows and built nests. It is on the Red List in Denmark and Sweden, but not in the British Isles or other areas.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Purse-web spiders undergo the same simple three stage metamorphosis of all spiders: embryonic, larval, and nympho-imaginal, with each stage separated by a molt. Eggs are fertilized in the uterus externus. Sperm moves towards the center of the egg, as does the female pronucleus, and conjugation of the two nuclei occurs 1-2 hours later. The zygote undergoes cleavage, forming a thin blastoderm with a concentrated yolk center (blastula) after 35 hours. The perivitelline, fluid-filled blastocoel is created by the sinking of the yolk granules. The polarity of the embryo emerges after the blastula contracts. The embryonic and larval stages do not possess developed organ systems and the larval stage is unable to feed independently, relying on yolk for nutrition. Once spiders reach the nympho-imaginal period, they are self-sufficient. The nymph (juvenile) and imago (adult) are very similar, differing only in sexual maturity.

Development - Life Cycle: metamorphosis

There is no specific information available on whether or not purse-web spiders affect humans negatively. However, they are a rare and typically shy species, so it is unlikely that they do.

There is no specific information available on whether or not purse-web spiders affect humans positively; however, they do feed on pests that humans generally consider a nuisance.

Positive Impacts: controls pest population

Purse-web spiders act as a predators of insects and serve as a food source to other spiders, birds, and mammals, as well as the only known host of a spider-hunting wasp (Aporus unicolor), which stings and lays its eggs on the spiders.

Commensal/Parasitic Species:

• Aporus unicolor (Family Pompilidae, Class Insecta)

During mating season (autumn, typically), males locate females' burrows and tap the outer silk tube of her web. If the female is receptive, he will be allowed to enter the burrow and they will mate for several hours. Breeding partners will live together in the female's burrow until the death of the male; the female then consumes the male's body which provides nutrients for the developing eggs.

Mating System: monogamous

Female and male purse-web spiders generally do not reach sexual maturity until 3 years of age; average age at sexual maturity is 4 years. After copulation, females produce an egg cocoon the following summer which is suspended in the tube of her web. Juveniles remain in the burrow until after their second instar (approximately 18 months after initial copulation). No information is available on the number of offspring/clutch.

Breeding interval: These spiders breed yearly.

Breeding season: Autumn

Average gestation period: 6 months.

Range time to independence: 8 to 10 months.

Range age at sexual or reproductive maturity (female): 3 to 4 years.

Average age at sexual or reproductive maturity (female): 4 years.

Range age at sexual or reproductive maturity (male): 3 (low) years.

Average age at sexual or reproductive maturity (male): 4 years.

Key Reproductive Features: semelparous ; iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous

Although their bodies are consumed by females, providing nourishment during gestation, males die before their offspring hatch, so females are solely responsible for parental care. Females suspend the egg cocoon within the tube of their web where it can be protected. After the offspring hatch, they remain in their mother's burrow for the better part of their first year of life.

Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)

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).

Conservation action has not been targeted at this widespread species.

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).

Inhabits rough grassland and heathland (2) on sandy or chalky soils (3).

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).

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

This species is not threatened.