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Behavior

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Although they can see, these spiders do not rely on vision for mate or prey recognition due to their poor eyesight. However, like most spiders, they use chemical signals to detect and respond to predators, prey, and mates. Spitting spiders use their raised front legs to detect prey and their environment using trichobothria (sensory hairs) on the metatarsi (second to last segment of the leg). These sensory hairs also contain chemoreceptors, which are sensitive to pheromones. Scytodes are also known to employ both acoustic and vibrational communication by tapping on the ground with their first pair of legs.

Communication Channels: visual ; tactile ; acoustic ; chemical

Other Communication Modes: pheromones ; vibrations

Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Conservation Status

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This species is a common house spider of the United States. It is less commonly found in Europe, Argentina, and Japan, but its conservation status is not a concern.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Life Cycle

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All spiders reproduce sexually, and sex is determined by meiosis. Following copulation and egg fertilization, females lay eggs in a cocoon carried under their bodies for 2-3 weeks until eggs hatch. Spiderlings remain with their mothers until their first molts and then disperse to live solitary lives, reaching adulthood after 5-7 molts. It can take 2-3 years for females to reach maturity.

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Benefits

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Though this species plays a role in controlling insect populations, it may also be considered a household pest. Many home-owners invest in pest-control in order to exterminate these spiders. Additionally, this spider is venomous, although its chelicerae, or fangs, are too small to pierce human flesh.

Negative Impacts: household pest

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Benefits

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This species contributes to the disposal of household pest insects and could potentially save homeowners money on investing in other methods of pest control.

Positive Impacts: controls pest population

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Associations

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When associated with humans, this spider's largest ecosystem role is in the control of insect populations, mostly of household pest species. They also serve as food for house centipedes (Scutigera coleoptrata) and other arthropod carnivores found in homes. In the wild, they may be preyed upon by a number of other species.

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Trophic Strategy

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Scytodes are active nocturnal wanderers, not web-spinners. They are insectivores and when living indoors, they mostly eat other insects and arthropods, such as moths (Order Lepidoptera), Flies (Order Diptera), other spiders (Order Araneae), and household bugs (Order Heteroptera). When living outdoors, they eat similar food items and, in the Philippines, are known to eat insects such as green scale (Coccus viridis), black citrus aphids (Toxoptera aurantii), citrus mealybugs (Planococcus citri), Philippine katydids (Phaneroptera furcifera) and lime swallowtails (Papilio demoleus). In Britain, mosquitos (Family Culicidae) are often eaten. Many of their prey items are significantly larger than these spiders. Females may also occasionally consume their own egg sacs.

Animal Foods: insects

Primary Diet: carnivore (Eats eggs, Insectivore )

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Distribution

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Members of the genus Scytodes are predominately tropical or subtropical spiders. However, spitting spiders are found scattered across neartic, paleartic, and neotropical regions. This species is commonly found in the eastern United States, as well as in Britain, Sweden and other European countries. Specimens have also been found in Japan and Argentina. It is unclear which populations are native and which are introduced in these regions. The presence of this species in more northern climates is attributed to the availability of warm houses and buildings, to which these spiders have adapted.

Biogeographic Regions: nearctic ; palearctic ; neotropical ; oceanic islands

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Habitat

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Spitting spiders are found in temperate forests. When associated with humans, they are most commonly found in dark corners, cellars, cupboards, and closets of houses and other buildings.

Average elevation: Sea Level m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: urban ; suburban ; agricultural

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Life Expectancy

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Spitting spiders have a relatively long life span as they do not die following mating; males live 1.5-2 years and females live 2-4 years. Females may be preyed upon during their egg-carrying periods, while males often die of hunger and exhaustion while searching for and courting females.

Range lifespan
Status: wild:
1.5 to 4 years.

Average lifespan
Status: wild:
2.5 years.

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Morphology

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This species has long, thin, legs, and are glabrous (hairless), with the exception of short sensory setae scattered over the body. These spiders are also easily identified by their oversized cephalothorax (prosoma), which slopes upward towards their posterior ends. Their abdomens (which are roughly the same circular shape as the cephalothorax) slope downwards and are only slightly smaller than the cephalothorax. Like all spiders, these two body tagmata (segments) are separated by a thin pedicel (waist-like connector).

Large, well-developed poison glands are located in the cephalothorax. These glands are divided into two parts: a smaller, anterior compartment which stores venom and a larger, posterior compartment which contains a mucilaginous substance. These spiders produce a gummy substance which is a mix of the two substances and is excreted by their fused chelicerae, which can not be moved separately. Scytodes are ecribellate, lacking the silk-spinning organ (cribellum) of some other spiders. They have a single tracheal spiracle.

Spitting spiders have pale yellow bodies with black speckled markings on the cephalothorax, which slightly resemble a lyre. Their legs, which slowly taper in size as they extend from their bodies, are long with black bands. The most anterior portion of the head, below the eyes, projects forwards, past the mandibles. This species exhibits sexual dimorphism, with males typically ranging from 3.5-4 mm in length and females ranging from 4-5.5 mm.

Range length: 3.5 to 5.5 mm.

Other Physical Features: ectothermic ; bilateral symmetry ; venomous

Sexual Dimorphism: female larger

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Associations

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Since spitting spiders are slow moving, they use their spitting apparatus against predators, rather than attempting to flee. Indoors, the majority of its predators are household arthropods such as other spiders and centipedes, and may include mammals such as domestic cats. In the wild, spitting spiders may be prey for bats, toads, birds, and shrews. Additionally, humans play a major factor in controlling populations of this species through pest control.

Known Predators:

  • Common house spider (Parasteatoda tepidariorum)
  • Wolf Spiders (Hogna carolinensis)
  • House centipede (Scutigera coleoptrata)
  • American toad (Anaxyrus americanus)
  • Little brown bat (Myotis lucifugus)
  • House Sparrow (Passer domesticus)
  • Domestic cat (Felis catus)
  • Shrew (Soricidae sp.)
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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Reproduction

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Spitting spiders are solitary, interacting only during mating. These spiders are aggressive hunters, so males must approach females cautiously or else be mistaken for prey. Both sexes produce pheromones, which are detected through contact with chemosensory hairs covering the pedipalps and first pair of legs; female mate choice is based on male pheromone production. Location of mates is not based on visual cues and mating usually occurs following an accidental meeting of a male and female. Upon meeting a female, male spitting spiders fill their palpal organs (accessory reproductive parts on the ends of each pedipalp) with sperm. They do this by drawing a sperm web across their genital openings to accumulate sperm droplets, using their third pair of legs. In Scytodes, the sperm web is a single thread which typically takes a triangular shape. From there, sperm droplets are drawn into the palpal organ (bulb). Males approach females anteriorly; females raise their cephalothoraxes to allow males to insert both palpal organs into their genital opening. Sperm is then deposited and stored in females' seminal receptacles. After mating, the pair separates immediately. Males and females have multiple partners throughout their lifetimes.

Mating System: polygynandrous (promiscuous)

Spitting spiders are dioecious and females require 2-3 years to reach maturity. Most mating occurs in the warmer months (especially August) but these spiders can expand their breeding seasons when living in warm areas, such as within homes. Sperm can be stored by females for months until eggs are laid. Compared to most spiders, spitting spiders lay relatively few eggs (20-35 eggs per cocoon) and 2-3 cocoons are typically produced by a female each year. This species displays maternal care both before (females carry egg cocoons) and after hatching, with newly hatched juveniles remaining with their mother until their first molts. Speed of growth and, therefore, rate of molting, is closely related to availability of prey and so the time that juveniles remain with their mother, as well as the age at which males reach maturity, is widely variable. These spiders can mate multiple times and usually die of hunger, exhaustion, or predation.

Breeding interval: This species breeds 2-3 times a year.

Breeding season: These spiders breed during warmer summer months.

Range number of offspring: 20 to 35.

Average number of offspring: 28.

Average age at sexual or reproductive maturity (female): 2-3 years.

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

Female spitting spiders exhibit parental care. They do not make nests or suspend cocoons in webs or other structures, but instead lay eggs in a cocoon that they carry either under their bodies or in their chelicerae. Females are more vulnerable to predation during this egg-carrying period, as they are unable to feed or defend themselves by spitting. Eggs typically hatch 2-3 weeks after being laid and nymphs (juveniles) remain with their mothers until their first molts. On occasion, females consume egg sacs that have resulted from mating with non-preferred males or contain defective eggs. Males display no parental investment after mating.

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

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Brand, J. 2013. "Scytodes thoracica" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Scytodes_thoracica.html
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Jacqueline Brand, University of Michigan-Ann Arbor
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Jeremy Wright, University of Michigan-Ann Arbor
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Scytodes thoracica

provided by wikipedia EN

Scytodes thoracica is a spitting spider, so called because it spits a venomous sticky silken substance over its prey. Its size ranges between 3–6 mm (0.12–0.24 in). The carapace is unusual in sloping upwards towards its rear end, whereas the abdomen slopes downwards.

It has six eyes instead of the eight spiders usually have. It has a wide distribution: found in "Europe, North Africa, Turkey, temperate Asia to China, Korea, Japan. Introduced to North America, Argentina, India, Australia, New Zealand."[1]

This particular spitting spider features the presence of silk glands in its cephalothorax. Besides the silk glands in its abdomen, the spider also has silk glands connected with its venom glands. In this way the spider has the ability to make venomous silk. Other arachnids may also have silk glands in their cephalothorax, such as the pseudoscorpions.

Hunting tactics

Schematic illustration of an immobilised prey

In contrast to the pseudoscorpions that use the silk from the cephalothorax glands to make nests, the spitting spider uses it to catch prey in a very particular way. It is a very slow hunter as its long and tender legs may suggest. During night, when some insects are less active, Scytodes starts its hunt. The spider sneaks very carefully towards its prey and, from about 10 mm (0.39 in), stops and carefully measures the distance to its prey with one front leg without disturbing it. Then it squeezes the back of its body together and spits two silk threads, in 1/600 s, in a zigzag manner over the victim. The prey is immediately immobilized. When the prey is larger the spider spits several times. It is assumed the spider uses special long hearing hairs located at its legs to locate its prey.

Habitat

Scytodes thoracica is nocturnal. It prefers warm temperatures and is not rare inside houses. In Southern Europe, it can be found under stones outside houses. In Northern Europe it can only be found in houses. They can be found worldwide.

Reproduction

The mother makes a nursery web for the emerged spiderlings, and carries her eggs under her belly in a net of silk.

References

  1. ^ "Scytodes thoracica". World Spider Catalog. Retrieved 22 August 2017.

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Scytodes thoracica: Brief Summary

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Scytodes thoracica is a spitting spider, so called because it spits a venomous sticky silken substance over its prey. Its size ranges between 3–6 mm (0.12–0.24 in). The carapace is unusual in sloping upwards towards its rear end, whereas the abdomen slopes downwards.

It has six eyes instead of the eight spiders usually have. It has a wide distribution: found in "Europe, North Africa, Turkey, temperate Asia to China, Korea, Japan. Introduced to North America, Argentina, India, Australia, New Zealand."

This particular spitting spider features the presence of silk glands in its cephalothorax. Besides the silk glands in its abdomen, the spider also has silk glands connected with its venom glands. In this way the spider has the ability to make venomous silk. Other arachnids may also have silk glands in their cephalothorax, such as the pseudoscorpions.

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