Pisaurina mira

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Pisaurina mira
Nursery Web Spider - Pisaurina mira, Julie Metz Wetlands, Woodbridge, Virginia - 15621919300.jpg
Nursery Web Spider - Pisaurina mira, Julie Metz Wetlands, Woodbridge, Virginia - 10434420074.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Pisauridae
Genus: Pisaurina
Species:
P. mira
Binomial name
Pisaurina mira
(Walckenaer, 1837) [1]

Pisaurina mira, also known as the American nursery web spider, due to the web it raises young in, is a species of spider in the family Pisauridae. They are often mistaken for wolf spiders (Lycosidae) due to their physical resemblance. P. mira is distinguished by its unique eye arrangement of two rows.  

Contents

P. mira is known for its wide distribution across eastern North America and tend to inhabit high weeds or low shrubs in ecotonal areas. [2] It is categorized as a "sit-and-wait ambush predator" that waits for prey to come within reach and snatches them using its chelicerae (clawlike pincers). [3]  

P. mira is most well known for its sexually cannibalistic behavior and extensive use of silk web in mating. Prior to copulation, the male binds the female's legs with his silk to avoid being consumed by the female. This silk use for survival has been found to increase P. mira males' reproductive fitness, as they typically engage in mating with multiple females when not manipulated.

Like other members of the Pisauridae, P. mira carries its eggs along with it in a sac that is secured both by a thread of silk linking it to the spider's spinnerets and by being held by the spider's chelicerae.

When the eggs are nearly ready to hatch the mother builds a nursery web within which the egg sac is then hung. After they hatch, and until their first molt, the infant spiders inhabit the rather large volume enclosed by this nursery web. The mother spider stations herself nearby to defend the nursery. [4] The responsibility of parental care is upheld solely by the female, as males who survive the sexually cannibalistic female during mating depart to mate with more females. [5]

Although the venom of P. mira is enough to kill its prey, which are usually small insects, it is insufficient for any lethal damage to bigger animals or humans. [3]

Anterior view demonstrating the typical eye pattern Anterior view of Pisaurina mira (Nursery Web Spider, family Pisauridae) (22567469183).jpg
Anterior view demonstrating the typical eye pattern

Description

Pisaurina mira, commonly referred to as the nursery web spider, has a moderately high carapace, a hard layer that provides outer protection for the cephalothorax (combined head and thorax region). [2] The abdomen is moderately long, typically less than twice the length of carapace. [2]

P. mira is distinguished from other species similar in general morphology with its unique straight anterior row of eyes. [2] The eight eyes are arranged in two rows: four eyes in the front form a straight line, and four eyes in the back form a U-shape. It is a sexually dimorphic species, with the male spiders generally having longer legs and a larger leg length to body ratio than the females. [6]

The patterns of P. mira range from a distinct dark median band on the abdomen to an indistinct median band with two rows of lateral spots. [2]

Habitat

Nursery web spiders are wandering hunters. They are usually found on vegetation or at water margins throughout North America. [7] Pisaurina mira is usually seen in the woods and meadows, but it is most populated in the transitional areas between woods and fields. [2] They inhabit tall grass, shrubs, and bushes, which gives them an advantage considering their hunting strategy, waiting for prey to come within their reach and using their pincers ("sit-and-wait ambush predator"). [7]

Geographic range

Nursery web spiders are distributed across Eastern North America, ranging from Ontario and Quebec, extending southward to central Florida and the Rio Grande Valley of Texas. [2] They also extend westward to Minnesota, Kansas, and Oklahoma. [2]

Diet

Pisaurina mira are active hunters. Instead of setting up a spider web to passively wait for prey, the most significant silk use in P. mira is centered around the mating behavior. In order to obtain food, the nursery web spiders wander around, hunting for insects such as gnats and mosquitoes. They use their chelicerae to grab the prey. While P. mira's venom is not lethal, it injects digestive juices into their prey and liquifies the prey's internal organs. The vast majority of nutritional intake for the nursery web spiders come from this soup of liquified organs. [3]

Heat tolerance

Compared to the wolf spider ( Tigrosa helluo ), a species that is often considered similar to the nursery web spiders, P. mira exhibits lower heat tolerance (critical thermal maxima parameter (CTM50) = 34 °C). [8] Likewise, with increasing temperature, the nursery web spiders become weaker predators, resulting in noticeably decreased prey mortality rate. At warmer temperatures, there is an increase in metabolism and energy demand. Due to the heat sensitivity of the nursery web spiders, the increased stress stemming from higher temperature result in the relinquishment of remarkable predator abilities.

Webs

Females will gather leaves to build nursery webs when their eggs are near hatching. [3] Once hatched, the spiderlings will inhabit this web until their first molt. During this time, the female guards the web from predators. [4]

With damselfly prey Nursery web spider with damselfly prey (29419815556).jpg
With damselfly prey

Reproduction

Mating for P. mira typically occurs in mid-June to mid-July. The female first transfers her eggs into a cocoon under her abdomen. She embraces this cocoon until the eggs are ready to hatch. While awaiting this process, the female also builds a "nursery web" by gathering leaves together, a safe place where the spiderlings will grow. [3]

Nursery web spiders are known to be univoltine, [7] which means it only has one brood of offspring per year. The care of the offspring is typically solely the female's responsibility; from carrying eggs to maintaining the sac until hatching, the female does most of the work, and the male's role is very limited. The spiderlings molt multiple times, and at each stage, a larger skin develops to accommodate for the growing spider. The weaning phase begins after the spiderlings' first molt, with the departure of spiderlings from the nursery. [3]

Female with egg sac Big Mama 07.23.22.jpg
Female with egg sac

Behavior

Mating

The female P. mira is known to be sexually cannibalistic. In order to avoid being eaten by the female during mating, the male P. mira wraps the legs of the females in silk prior to and during copulation. More specifically, the male uses his silk to immobilize the female's legs I and II while he holds her legs III and IV. [9]

Prior to mating, the male follows the female, periodically releasing his dragline (a line of spider silk). Slowly approaching the female from behind, the male traces the female's path until he reaches the female's hind legs.

For the actual mating stage, both the male and the female release draglines. The female hangs freely from her dragline, while the male uses his dragline to reach the female. The male nursery web spider then rotates the female about three to five times, wrapping his silk around her legs and immobilizing them. Throughout this stage, the legs of the female are fixed in a flexed position, bounded by either the veil of silk from the male, or the legs of the male. [9] Because the male legs play a significant role in immobilizing the female during mating and copulation, longer leg length in males are associated with greater chances of copulation and lower risk of being cannibalized in males.

Because the female grows increasingly active throughout repeated copulations, copulatory silk wrapping is assumed to be an example of a self-defense mechanism adopted by the male nursery spiders. However, as this behavior of female wrapping by the male remains rare among spiders, further investigation is necessary.

Number of mates

When the male P. mira is able to successfully avoid sexual cannibalism, it mates with multiple females to increase the numbers of offspring. The lack of responsibility for parental care distributed to P. mira is a key component behind this behavior. Unmanipulated male P. mira is known to successfully mate with up to 5 different females, [5] as single mating does not deplete the sperm storage in the pedipalps of the male nursery web spider. Thus, this consecutive mating may occur in relatively short time frames, ranging from a single night to a 72-hour window. [5] Because the use of silk web to immobilize during copulation can ensure a greater chance at multiple mating, we can assume it to be a positive trait that is selected for among the males.

Nuptial gift

The silk generated by the male P. mira is rather versatile; when courting a female nursery web spider, the male spider offers her a "nuptial gift," usually a prey wrapped up in the male's silk. This act of gift-giving serves as the first stage of mating, preceding copulation. The female spider then has a choice to either accept the gift and follow through with mating, or chase the male away. After copulation, the male typically takes the nuptial gift back with him. [3]

Copulation

As seen above, copulation in nursery web spiders is facilitated by the unique silk wrapping behavior observed in males. In males, sperm is stored in organs called pedipalps. As male P. mira transfer approximately the same amount of sperm from pedipalps per insertion, increased insertion number was found to result in increased sperm transfer. An increased number of sperm in P. mira also typically leads to an increase in the number of offspring, but the causal relationship still remains unclear. [10] It is, however, still presumed that the silk wrapping is a trait evolved in males for an advantage in sexual selection and a maximization of reproductive fitness.

Sexual cannibalism

In nursery web spiders, females are known to frequently engage in sexual cannibalism. While sexual cannibalism is assumed to grant a greater chance at reproductive success for both spiders, with better fit and larger offspring, P. mira males can most likely obtain greater reproductive success by avoiding sexual cannibalism and ensuring survival themselves. More specifically, the use of silk veils was found to often grant higher fertilization success, as it interfered with the female's tactile and chemical receptors. [11] Upon being trapped in the silk veil, the female P. mira shows increased movement in order to free themselves, and the attempts at sexual cannibalism may continue regardless of the veil. [11]

Interaction with humans

Pisaurina mira, as one of the most common spiders found in eastern United States, is well integrated in human lives. While the venom of P. mira is lethal to its prey, it is not effective against larger targets and is thus very unlikely to be medically significant for humans. [3]

Agricultural impact

Because the vast majority of nursery web spiders' diet consists of insects found on fields and other cultivation sites for crops, they inevitably have an effect on the population of bugs and pests who feed on those crops and share the same habitats. The seasonal fluctuation of prey population affects the seasonal fluctuation of the P. mira population as well. For example, the highest population level of tarnished plant bugs, a prevalent pest for crops in the United States, was marked in October and June. [7] The eggs of P. mira hatch in May, and the immature spiderlings are dispersed from nursery webs in June. [7] Mature males are most collected in May and June. [2] Thus, the interconnectedness of the population of these two species largely influence the crop yield. However, because P. mira's diet as a carnivore is rather diverse, a decline in the population of one prey does not hold much significance, as P. mira is able to hunt for other available insects. [7]

Contribution to the ecosystem

P. mira contributes to the increase of carbon storage by reducing grasshopper herbivory. The presence of P. mira alters the dietary habits of grasshoppers, which consequently increases the carbon storage by allowing the plants to take over a larger area for photosynthesis as they can conserve the resources that were once reserved for self-protection. [12] They are also known to consume tarnished plant bugs, a pest that holds economic significance on many crops in the United States, mostly for small fruits and vegetables. [7]

Related Research Articles

<span class="mw-page-title-main">Nursery web spider</span> Family of spiders

Nursery web spiders (Pisauridae) are a family of araneomorph spiders first described by Eugène Simon in 1890. Females of the family are known for building special nursery webs. When their eggs are about to hatch, a female spider builds a tent-like web, places her egg sac inside, and stands guard outside, hence the family's common name. Like wolf spiders, however, nursery web spiders are roaming hunters that do not use webs for catching prey.

<i>Nephila</i> Genus of spiders

Nephila is a genus of araneomorph spiders noted for the impressive webs they weave. Nephila consists of numerous species found in warmer regions around the world, although some species formerly included in the genus have been moved to Trichonephila. They are commonly called golden silk orb-weavers, golden orb-weavers, giant wood spiders, or banana spiders.

<span class="mw-page-title-main">Raft spider</span> Species of spider

The raft spider, scientific name Dolomedes fimbriatus, is a large semi-aquatic spider of the family Pisauridae found throughout north-western and central Europe. It is one of only two species of the genus Dolomedes found in Europe, the other being the slightly larger Dolomedesplantarius which is endangered in the UK.

<i>Trichonephila clavipes</i> Species of spider native to the Americas

Trichonephila clavipes, commonly known as the golden silk orb-weaver, golden silk spider, golden orb weaver spider or colloquially banana spider, is an orb-weaving spider species which inhabits forests and wooded areas ranging from the southern US to Argentina. It is indigenous to both continental North and South America. Known for the golden color of their silk, the large size of their females, and their distinctive red-brown and yellow coloring, T. clavipes construct large, asymmetrical circular webs attached to trees and low shrubs in woods to catch small- and medium-size flying prey, mostly insects. They are excellent web-builders, producing and utilizing seven different types of silk, and they subdue their prey by injecting them with venom, as opposed to related species which immobilize their prey by wrapping them in silk first. They are not known to be aggressive towards humans, only biting out of self-defense if touched, and their relatively harmless venom has a low toxicity, posing little health concern to healthy human adults. Due to their prevalence in forests, T. clavipes may be encountered by hikers.

<i>Argiope keyserlingi</i> St Andrews cross spider

Argiope keyserlingi is a species of orb-web spider found on the east coast of Australia, from Victoria to northern Queensland. It is very similar in appearance to a closely related north Queensland species, Argiope aetherea. A. keyserlingi is commonly found in large populations in suburban parks and gardens, particularly among the leaves of Lomandra longifolia. Like many species of orb-web spiders, A. keyserlingi shows considerable sexual dimorphism, with the females being many times larger than the males. Mature females can be seen during the summer, and seeing multiple males on the web of one female is not uncommon.

<i>Misumena vatia</i> Species of spider

Misumena vatia is a species of crab spider with a holarctic distribution. In North America, it is called the goldenrod crab spider or flower (crab) spider, as it is commonly found hunting in goldenrod sprays and milkweed plants. They are called crab spiders because of their unique ability to walk sideways as well as forwards and backwards. Both males and females of this species progress through several molts before reaching their adult sizes, though females must molt more to reach their larger size. Females can grow up to 10 mm (0.39 in) while males are quite small, reaching 5 mm (0.20 in) at most. Misumena vatia are usually yellow or white or a pattern of these two colors. They may also present with pale green or pink instead of yellow, again, in a pattern with white. They have the ability to change between these colors based on their surroundings through the molting process. They have a complex visual system, with eight eyes, that they rely on for prey capture and for their color-changing abilities. Sometimes, if Misumena vatia consumes colored prey, the spider itself will take on that color.

<i>Nephila pilipes</i> Species of spider

Nephila pilipes is a species of golden orb-web spider. It resides all over countries in East and Southeast Asia as well as Oceania. It is commonly found in primary and secondary forests and gardens. Females are large and grow to a body size of 30–50 mm, with males growing to 5–6 mm. It is the second largest of the orb-weaving spiders apart from the recently discovered Nephila komaci. The first, second, and fourth pairs of legs of juvenile females have dense hairy brushes, but these brushes disappear as the spider matures.

<span class="mw-page-title-main">Sexual cannibalism</span> Practice of animals eating their own mating partners

Sexual cannibalism is when an animal, usually the female, cannibalizes its mate prior to, during, or after copulation. This trait is observed in many arachnid orders, several insect and crustacean clades, gastropods, and some snake species. Several hypotheses to explain this seemingly paradoxical behavior have been proposed, including the adaptive foraging hypothesis, aggressive spillover hypothesis and mistaken identity hypothesis. This behavior is believed to have evolved as a manifestation of sexual conflict, occurring when the reproductive interests of males and females differ. In many species that exhibit sexual cannibalism, the female consumes the male upon detection. Females of cannibalistic species are generally hostile and unwilling to mate; thus many males of these species have developed adaptive behaviors to counteract female aggression.

<i>Dolomedes minor</i> Species of spider

Dolomedes minor is a spider in the family Pisauridae that is endemic to New Zealand, where it is known as the nursery web spider.

<i>Amaurobius ferox</i> Species of spider

Amaurobius ferox, sometimes known as the black lace-weaver, is a common nocturnal spider belonging to the family Amaurobiidae and genus Amaurobius. Its genus includes three subsocial species, A. fenestralis, A. similis and A. ferox, all three of which have highly developed subsocial organizations.

<i>Trichonephila plumipes</i> Species of spider

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<span class="mw-page-title-main">Six-spotted fishing spider</span> Species of spider

The six-spotted fishing spider is an arachnid from the nursery web spider family Pisauridae. This species is from the genus Dolomedes, or the fishing spiders. Found in wetland habitats throughout North America, these spiders are usually seen scampering along the surface of ponds and other bodies of water. They are also referred to as dock spiders because they can sometimes be witnessed quickly vanishing through the cracks of boat docks. D. triton gets its scientific name from the Greek mythological god Triton, who is the messenger of the big sea and the son of Poseidon.

Formally, a nuptial gift is a material presentation to a recipient by a donor during or in relation to sexual intercourse that is not simply gametes in order to improve the reproductive fitness of the donor. Often, such a gift will improve the fitness of the recipient as well. This definition implies neutral gifts, costly gifts and beneficial gifts regarding the fitness of the recipient.

<i>Holocnemus pluchei</i> Species of spider

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<i>Micrathena mitrata</i> Species of spider

Micrathena mitrata, the white micrathena, is a species of orb weaver in the spider family Araneidae. It is found in a range from the United States to Brazil. The spider has a distinctive appearance with a shiny, black abdomen and spiky, yellowish-brown legs. Its body length ranges from 4 to 9 mm in females and 3 to 4 mm in males. The species is known for its elaborate web, which it uses to capture insects for food. Despite its fearsome appearance, Micrathena mitrata is not considered dangerous to humans and is generally regarded as a harmless spider.

Agelenopsis pennsylvanica, commonly known as the Pennsylvania funnel-web spider or the Pennsylvania grass spider, is a species of spider in the family Agelenidae. The common name comes from the place that it was described, Pennsylvania, and the funnel shape of its web. Its closest relative is Agelenopsis potteri.

<i>Pardosa milvina</i> Species of arachnid

Pardosa milvina, the shore spider, is a species in the wolf spider family. They are mainly found near rivers and in agricultural areas in eastern North America. P. milvina feed on a large variety of small insects and spiders. Ground beetles such as Scarites quadriceps and large wolf spiders such as Tigrosa helluo are predators of P. milvina. P. milvina are smaller spiders with thin, long legs. This species captures prey such as arthropods with their legs and then kills them with their venom. Their predators are larger wolf spiders and beetles. P. milvina are able to detect these predators from chemotactile and vibratory cues. These spiders lose limbs when escaping from predators and they can change their preferred location in order to avoid predators. P. milvina also use chemical cues in order to mate. During their mating ritual, the male raises his legs and shakes his body. Both males and females can use silk, a chemotactile cue, for sexual communication. Additionally, female shore spiders heavily invest in their offspring, keeping them in egg sacs and carrying them for a few weeks after they are born.

<i>Leucauge mariana</i> Species of spider

Leucauge mariana is a long-jawed orb weaver spider, native to Central America and South America. Its web building and sexual behavior have been studied extensively. Males perform several kinds of courtship behavior to induce females to copulate and to use their sperm.

<i>Pardosa agrestis</i> Species of spider

Pardosa agrestis is a non-web-building spider in the family Lycosidae, commonly known as wolf spiders.

<i>Pardosa pseudoannulata</i> Species of arachnid

Pardosa pseudoannulata, a member of a group of species referred to as wolf-spiders, is a non-web-building spider belonging to the family Lycosidae. P. pseudoannulata are wandering spiders that track and ambush prey and display sexual cannibalism. They are commonly encountered in farmlands across China and other East Asian countries. Their venom has properties that helps it function as an effective insecticide, and it is, therefore, a crucial pesticide control agent.

References

  1. "Taxon details Pisaurina mira (Walckenaer, 1837)". World Spider Catalog. Natural History Museum Bern. Retrieved 2016-04-14.
  2. 1 2 3 4 5 6 7 8 9 Carico, James E. (1972-01-01). "The Nearctic Spider Genus Pisaurinae (Pisauridae)". Psyche: A Journal of Entomology. 79 (4): 295–310. doi: 10.1155/1972/59858 . ISSN   0033-2615.
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