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Spined Micrathena

Micrathena gracilis (Walckenaer 1805)

Brief Summary

provided by EOL authors

Female Micrathena gracilis are easily recognized by their bulky, striped or mottled abdomen adorned with five pairs of black-tipped spines. They are usually about 1 cm long. This species is sexually dimorphic. Males are much smaller than females, and their abdomen is long and flat and lacks prominent spines.

The Spined Micrathena lives in dense deciduous forests in eastern North America and Central America. Females construct a web in large open spaces in the understory. The web is two-dimensional with a sticky, densely woven spiral (Uetz & Hartsock 1987). It is used to trap flying insects. Flies (Diptera) are the most common prey (Uetz 1990, Uetz & Harstock 1987).

Mature males do not build webs (Bukowski & Christenson 1997, Hodge 1987). They visit females in their webs to mate. Sexual cannibalism appears to be rare in this species and has been observed only when two males courted a female simultaneously (Bukowski & Christenson 2000)

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Spined micrathena

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Micrathena gracilis is a spider in the family Araneidae (orb-weavers), commonly known as the spined micrathena. This spider spins a moderately large (can be about 20 cm long in diameter) and very tightly coiled web. The spiders themselves are small and can be found to be anywhere from 4.2 mm to 10.8 mm long (McCravy and Hessler 215-217).[1] It is completely harmless to humans as it contains no venom. The M gracilis is unique in appearance due to its large spiky abdomen and black and white bodies. Certain spiders of this species can also display a yellow color on the sides of their bodies (Vanderhoff et al. 470).[2] These spiders can be seen most active during the end of the summer and beginning of fall. The M. gracilis is diurnal and are rarely ever seen active at night (Magalhaes and Santos 14[3]).

Habitat/Webs

M. gracilis can be found in Northern Argentina as well as Eastern and Northern parts of North America. These spiders tend wander and rarely ever remain in the same web site for more than week. On average, they spend about 6–7 days on each web site. They are neotropical forest spiders and can be found more easily in hardwood forests that contain Oak and Hickory trees. They tend to like moisture; they are more easily found in woodland forests that are near a lagoon, pond, or other small bodies of water. One study even mentioned that these spiders were found in an area that tends to floor during their mating season (Bukowski and Christenson 308)[4] When constructing webs, the inner orbs of their webs are changed every night; however, they may keep the outer layer of the web the same for multiple days.[3]

Physical characteristics

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The central portion of a web of a Micrathena gracilis

Females are 8–10 mm long. They exhibit a bulbous abdomen with spines. Males exhibit a fair amount of sexual dimorphism. They tend to be about fraction of the size of the females. Also, they have fewer spines, a flatter abdomen, and a slightly lighter tone. Although males can produce silk, they mostly use it in the mating ritual.

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Spined micrathena view from underneath

Life cycle

Micrathena gracilis hatches in the spring, the image of an adult. After the summer's growth, the female lays eggs in a sack. These remain relatively dormant through the winter months. The general life span is one year in length.

References

  1. ^ McCravy, Kenneth (2012). "Abundance and web characteristics of Micrathena gracilis and Micrathena mitrata (Araneae: Araneidae) in west-central Illinois, USA". Journal of Arachnology. 40 (2): 215–217. doi:10.1636/p11-85.1.
  2. ^ Vanderhoff, Natasha (November 2008). "Do the Color and Pattern of Micrathena gracilis (Araneae: Araneidae) Attract Prey? Examination of the Prey Attraction Hypothesis and Crypsis". Journal of Insect Behavior. 21 (6): 469–475. doi:10.1007/s10905-008-9142-3.
  3. ^ a b Magalhães, Ivan L. F.; Santos, Adalberto J. (August 2012). "Phylogenetic analysis of Micrathena and Chaetacis spiders (Araneae: Araneidae) reveals multiple origins of extreme sexual size dimorphism and long abdominal spines: PHYLOGENY OF MICRATHENA AND CHAETACIS". Zoological Journal of the Linnean Society: no. doi:10.1111/j.1096-3642.2012.00831.x.
  4. ^ Bukowski, Todd C.; Christenson, Terry E. (1997). "Natural History and Copulatory Behavior of the Spiny Orbweaving Spider Micrathena gracilis (Araneae, Araneidae)". The Journal of Arachnology. 25 (3): 307–320. ISSN 0161-8202. JSTOR 3705597.

"
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Spined micrathena: Brief Summary

provided by wikipedia EN

Micrathena gracilis is a spider in the family Araneidae (orb-weavers), commonly known as the spined micrathena. This spider spins a moderately large (can be about 20 cm long in diameter) and very tightly coiled web. The spiders themselves are small and can be found to be anywhere from 4.2 mm to 10.8 mm long (McCravy and Hessler 215-217). It is completely harmless to humans as it contains no venom. The M gracilis is unique in appearance due to its large spiky abdomen and black and white bodies. Certain spiders of this species can also display a yellow color on the sides of their bodies (Vanderhoff et al. 470). These spiders can be seen most active during the end of the summer and beginning of fall. The M. gracilis is diurnal and are rarely ever seen active at night (Magalhaes and Santos 14).

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copyright
Wikipedia authors and editors
original
visit source
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