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Wolf spiders (family Lycosidae), are among the most common spiders worldwide. Their colors range from black to brown or tan with lengthwise dark and light stripes. Their eyes (they have eight) are arranged in three rows of four, two, and two. The anterior eyes (those in the first row) are smallest, and are in a straight line. The middle row has the largest eyes, and the eyes in most posterior row can be nearly as big as those in the middle. All eyes are dark in color.
The genus Pardosa is large, and itan be difficult to differentiate between species in this genus. In fact, only an expert can reliably tell members of the genus from one another. P. milvina does exhibit certain traits that distinguish it from other wolf spiders. The legs are long and thin with extremely long spines. Scopulae are claw tufts on spiders' legs that aid them in gripping during locomotion. This spider does not possess scopulae and therefore cannot climb smooth surfaces. The cephalothorax is highest in the head region, or carapace. Chelicerae are much smaller than in other wolf spiders, measuring 4 to 9.5 mm. The dorsal stripes common to wolf spiders are more wavy than in other species. The abdomen has yellow spots. Sexual dimorphism exists in this species. The males have white hairs on the patella of the legs. These spiders are considered small. The length of females ranges from 5.1 to 6.4 mm and male length ranges from 4.3 to 5.0 mm.
Range length: 4.3 to 6.4 mm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger; sexes colored or patterned differently
This wolf spider can be found in grasslands, dry open woods and also in wet grounds along streams and ponds. Recently, P. milvina has been found among various agricultural crops. This spider does not create a snare or web. Rather, it is somewhat nomadic, resting under rocks and grass in between hunting.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: suburban ; agricultural ; riparian
There are approximately 2,500 species of wolf spiders worldwide.
Visual and tactile communication occur during courtship. Visual stimuli are important to this species in capturing prey. These spiders respond to vibrations.
Communication Channels: visual ; tactile
Perception Channels: visual ; tactile ; vibrations
This species is not a special conservation concern.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
This spider is able to bite humans if defending itself. These bites can cause skin irritation or possibly lesions.
Negative Impacts: injures humans (bites or stings)
Most believe that P. milvina benefits humans by limiting insect and pest populations. Like most other spiders, P. milvina is a generalist, eating a variety of other animals (mostly other invertebrates). This leads some to believe that this increases the spider's effectiveness as a population limiter. Yet others feel that since the spider does not specialize in any single species and does not live in colonies, it cannot effectively limit the populations of pests. Thus, although P. milvina shows behaviors which are of potential benefit to humans, it is difficult to determine the extent of the actual benefit provided.
Positive Impacts: controls pest population
Like most every spider, P. milvina is carnivorous. Previously thought of as active hunters, this wolf spider appears to obtain food more often as a "sit-and-wait" predator. This makes P. milvina a bit different from most other wolf spiders, which tend to hunt by sight and chase prey. Wolf spiders are so named because of the way in which they pounce on their prey with great speed and strength. The spider then envenoms its prey with fangs, at the same time puncturing the body so it may suck the body fluids. Staying near the ground during the day, large numbers have been found feeding in cotton fields at night. Common food includes the cotton fleahopper, insect eggs, crickets, locusts, ants, grasshoppers, and other spiders. Pardosa milvina eats about 3.5 mg of insects daily, equivalent to 12% of its body weight.
Animal Foods: body fluids; insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Insectivore )
A common and widespread spider in North America, Pardosa milvina can be found in the United States from New England to Florida and west to the Rocky Mountains. It is most common in the eastern third of Texas between the months of May and September.
Biogeographic Regions: nearctic (Native )
Male wolf spiders mature in spring and perform elaborate courtship dances on sunny days. A male waves at a female vigorously with both pedipalps (legs), raises them, and at the same time performs a few dancing steps. Males must be cautious in their approach, for a female may decide he is food and not a mate. If he succeeds, the male then mounts the female's back, inserting his pedipalp into the epygynum of the female and transferring sperm.
Eggs are laid soon after mating and are bundled in an oval-shaped, compact silk egg sac or cocoon. The cocoon is green primarily, and then turns to dirty gray. Females carry the egg sac at all times, attached to the spinnerets. This leaves her jaws free for action at all times. Female wolf spiders are well known for their care of offspring. When the cocoon is mature, the mother rips it open, aiding her babies in emerging. The offspring climb onto their mother's back. Babies can number more than one hundred; so several layers are formed on the mother. Here they remain there for approximately one week before leaving to fend and feed for themselves.
Range number of offspring: 100+ (high) .
Average time to independence: 1 weeks.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Female wolf spiders are known to provide fairly extensive parental care to their young. Females carry their egg sac with them, providing the developing young with protection. When the young spiders hatch, a female helps them to emerge from the egg sac. The newly hatched young are carried on the mother's back for about one week.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female); pre-independence (Protecting: Female)
Pardosa milvina, the shore spider, is a species in the wolf spider family.[1][2][3][4] 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.
The shore spider’s eyes are arranged in a characteristic pattern with the top row having four eyes and the subsequent rows having only two eyes each. They have thin, long legs with long spines. Pardosa milvina cannot climb smooth surfaces due to their lack of tufts of hair that are common at the end of legs on other spiders. These wolf spiders have smaller chelicerae and more wavy dorsal stripes than other spiders in this family. They have yellow spots on their abdomen and males have white hairs on their kneecaps.[5] Shore spiders are a smaller spider, as the largest female is approximately 6.2 mm in length and the largest male is approximately 4.7 mm.[6] Additionally, female spiders carry large egg sacs.[7]
Pardosa milvina are located in high densities near rivers and agricultural areas of eastern North America.[8] There are large variances in their abundance throughout the year, between months, or even from one year to the next.[8] They can also be found in dry, open woods near water, such as by rivers, ponds, and streams of New England, Georgia, and west of the Rockies.[6] Additionally, shore spiders are abundant in disturbed habitats and are commonly found on soil surfaces or in patches of mulch.[9]
Pardosa milvina are active cursorial predators and active foragers. They feed on ground-dwelling arthropods like crickets.[7] Thesey also consume Diptera, Collembola, Homoptera, Thysanoptera, small Orthoptera, and small spiders.[10] Although they are smaller spiders, they can overwhelm their prey with their chelicerae and legs. This species grabs prey with their legs and chelicerae, biting the prey until it is killed by the spider's venom. They sometimes roll onto their backs when they are fighting with the prey.[11] They can also eat juvenile Hogna helluo.[9]
Larger wolf spiders like Tigrosa helluo[12] and Hogna helluo [7] are predators of P. milvina. Ground beetles such as Scarites quadriceps are also predators of the shore spider. The adult Hogna helluo is 20 times larger than Pardosa.[9] [12] The egg sacs of female P. milvina contribute to predation and foraging costs. Females that don't have egg sacs are able to avoid predation as they are able to move more easily.[7]
One acrocerid that parasitizes P. milvina is Ogcodes eugonatus. Another parasite of shore spiders are mermithid nematode endoparasites. These can emerge from the ventral abdomen of shore spiders. Mermithids can cause behavioral and morphological changes in spiders, such as slower reaction times to predators, abdominal swelling, malformed legs and pedipalps, and undeveloped secondary sexual characteristics.[6]
Predators can announce their presence through signals or predator cues. P. milvina use chemotactile predator cues like silk, faeces, and other excreta in order to determine when a predator is nearby. They are then able to respond to the amount of predation risk based on these cues. When visual or chemotactile predator cues are not present, P. milvina can use vibratory cues in order to assess the risk from the predator. When they detect these predators through these cues, P. milvina decrease their activity. They only decrease activity when the predator is alerted to their presence. However, if the predator has not detected that the spider is nearby, this spider continues its activity. P. milvina are more responsive to isolated chemotactile cues as they are usually more reliable than vibratory cues alone. Chemotactile cues from predators can give Pardosa more specific information like the sex, size, diet, and hunger levels of the predator. Usually, these spiders only respond to the most threatening predator's vibratory cues. P. milvina will use vibratory cues mainly when they are the only information available to them. [12]
P. milvina changes their site preference in order to avoid predators. When there is presumably no danger present, P. milvina prefer more complex grass habitats over bare dirt. However, when there are predator cues, this preference is gone. P. milvina can capture more prey in dirt but they are more likely to be attacked by predators, specifically Hogna helluo. There is a tradeoff between the quality of habitat and the increased risk of predation. The negative effect of predation risk is worse than having slightly less food. P. milvina spiders are active foragers who can go to new habitats when threatened and remain successful in prey capture.[9]
The loss of legs in P. milvina is quite common. These spiders can sacrifice their legs in order to avoid predation, since these predators grasp their legs during an attack. If a male Pardosa were to lose its first pair of legs, it would decrease his overall fitness. This is because the frontal legs and their symmetry are an important characteristic when courting females. Even with a loss of limbs, there is little difference in the prey capture technique for Pardosa. The only difference is that those with no loss to the frontal legs are able to eat larger prey. This could lower the fitness of females by reducing the size of their egg sacs and number of eggs. When attempting to escape from a predator, P. milvina with leg loss were able to escape as they normally would. However, they might end up losing more limbs from this predator interaction. Spiders with all their legs might be better off because they have more limbs to give up to the predator and therefore escape. P. milvina could be able to survive with less legs since they are born with more legs than they actually require. They are able to give up some limbs in order to escape the predator.[11]
In addition to sexual pheromones on spider silk, researches have shown that Pardosa milvina possesses an airborne sexual communication capability. Researchers put unmated and mated females in pitfall traps and observe the behavior of adult males. The result is that males are more likely to fall into the traps with unmated females, showing airborne information can direct males to unmated females. After statistical tests, the results are statistically significant. However, the chemical composition of sexual pheromones of P. milvina remains unknown.
Males use substrate-borne chemical cues to gain information on the mating status of females. When males detect silk and pheromones from a virgin female, their courtship response is more energized. Males court the females by raising their legs and shaking their bodies. The rate at which the males lift their legs is an accurate representation of their assets since females who mate with males that raise their legs rapidly during courtship produce more surviving offspring. P. milvina can identify chemotactile cues like silk or feces from a predator. The courtship activity of males makes them more susceptible to attacks from Tigrosa helluo. The risk of attacks from predators affects the intensity of the male's courtship ritual. The symmetry of the front legs of a male P. milvina is related to the rate of his leg raises. Males with symmetrical front legs have a lower intensity courtship when there are predator cues present as they have a high potential for future mating and reproduction. However, males with asymmetrical front legs court with high intensity when predator cues are present because they are desperate to mate and reproduce as they might not have many opportunities.[8]
Female silk evokes male courtship behavior. Spiders use silk to chemically communicate with each other. Females use silk to release their sex pheromones indicating their mating status and willingness to mate with males. P. milvina produces three types of silk: dragline silk, attachment disks, and cord silk. Dragline silk are thin, white strands made from ampullate glands and are most likely used to get male attention. Attachment disks are made from piriform silk glands and can be used to keep dragline silk on to the substrate. However, these can still be made without other silk types. For example, male P. milvina use attachment disks to find the correct direction to follow females. Cord silk are thick, tan strands and are usually short. Females are able to tell the difference between silk from courting males and from non-courting males. When females are in the presence of courting males, they deposit more attachment disks and dragline silk. Cord silk deposition does not differ with the presence of courting or non-courting males. Females might be enhancing directional signals in order for the males to use attachment disks to follow females. This shows how silk is used for sexual communication.[13]
Females invest in brooding their offspring by making an egg sac by wrapping the eggs with fibrous sheets of silk. They attach this egg sac to their Spinneret and carry the sac for 12 to 30 days. The egg sac is off-white, tan, or blue in color. After this carrying period, the egg sac is torn and spiderlings emerge. These spiderlings are still carried by their mother for 3 to 24 days. The size and weight of these egg sacs make it harder for the female to attack prey and avoid predators. Occasionally, female shore spiders drop their egg sacs which could result in the death of the spiderlings.[7]
Shore spider, Pardosa milvina _BHL4428088.jpg)
Book of monsters (Page 40) BHL4428088 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.
Pardosa milvina est une espèce d'araignées aranéomorphes de la famille des Lycosidae[1].
Les anglophones l'appellent Shore spider.
Cette espèce se rencontre aux États-Unis à l'Est des montagnes Rocheuses et au Canada en Ontario et au Québec[1],[2].
Cette petite araignée commune vit le long des cours d'eau, dans les champs, les endroits dégagés, parmi les hautes herbes et depuis peu, les zones agricoles.
Cette araignée ne tissant pas de toile, chasse au sol, notamment en fouillant parmi les rochers et dans la végétation.
Les mâles mesurent de 4,3 à 5,0 mm et les femelles de 5,1 à 6,4 mm[3].
Sa livrée est brun roux, tachetée de gris et de noir. Son céphalothorax est oblong, élevé, la partie dorsale plate. Elles sont maculées, et ornées de bandes du tibia au tarse.
Les quatre yeux supérieurs sont plutôt proéminents et noirs. Les pattes sont plus étroites que les autres espèces du genre.
Le mâle se distingue aisément à ses pédipalpes globuleux, alors que ces appendices oraux de la femelle sont nettement plus fins. La femelle est un peu plus grande, et c'est la seule à transporter le sac à œufs accroché à ses filières.
Les stimuli sensoriels et visuels sont importants, notamment lors de la saison amoureuse et de l'accouplement. Autrement, le mâle pourrait être pris pour une proie et servir de pitance à la femelle.
Lors des jours ensoleillés, le mâle approche la femelle et agite vigoureusement ses pédipalpes tout en effectuant quelques pas de danse. Toutefois, il doit être prudent s'il ne veut être pris pour cible et se faire dévorer par la femelle.
Lorsque deux mâles se présentent simultanément pour conquérir une femelle, ceux-ci se livrent un duel. Ils tenteront d'intimider l'adversaire en effectuant des mouvements brusques et menaçants. C'est souvent celui qui prendra l'initiative qui obtiendra les faveurs de la femelle. Lorsqu'elle accepte, le mâle grimpe sur son abdomen, puis insère ses pédipalpes dans l'épigyne de la femelle.
Peu de temps après, la femelle pond 100 œufs, voire davantage. Elle les dépose dans un cocon de soie. De forme ovale, le sac à œufs est vert, puis devient gris terne. La femelle l'accroche à ses filières pour le transporter. Au moment de l'éclosion, la femelle déchire le sac afin de faciliter l'émergence des petits, qui grimperont alors sur le dos de la mère. Ils atteindront leur autonomie dès la deuxième semaine.
Sac à œufs accroché aux filières
Elle se nourrit d'orthoptères, tels les criquets et les sauterelles, de certains homoptères, d'arthropodes, d'œufs d'insectes et même de certaines espèces d'araignées[3].
L'araignée injecte un venin pour liquéfier les organes de sa proie, en la mordillant ci et là pour aspirer les liquides ainsi obtenus. Son apport quotidien équivaut à 12 % de sa masse corporelle, soit 3,5 mg de nourriture par jour.
Carnivore, Pardosa milvina adopte le mode passif pour chasser : Elle attend patiemment, puis saisit sa chance lorsqu'elle se présente, un mode peu commun chez les Lycosidae, généralement des araignées qui foncent vivement sur leurs proies.
Elle n'hésitera pas à mordre pour se défendre. Toutefois, sa morsure ne présente aucun risque, sinon une irritation de la peau, voire une petite lésion[3].
Pardosa milvina est une espèce d'araignées aranéomorphes de la famille des Lycosidae.
Les anglophones l'appellent Shore spider.
Pardosa milvina is een spinnensoort in de taxonomische indeling van de wolfspinnen (Lycosidae).[1]
Het dier behoort tot het geslacht Pardosa. De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd in 1844 door Nicholas Marcellus Hentz.
Bronnen, noten en/of referenties
Pardosa milvina[1] este o specie de păianjeni din genul Pardosa, familia Lycosidae. A fost descrisă pentru prima dată de Hentz, 1844.[2][3] Conform Catalogue of Life specia Pardosa milvina nu are subspecii cunoscute.[2]
|access-date= (ajutor)Mentenanță CS1: Nume multiple: lista autorilor (link) 
Acest articol referitor la un păianjen este un ciot. Puteți ajuta Wikipedia prin completarea sa. Pardosa milvina este o specie de păianjeni din genul Pardosa, familia Lycosidae. A fost descrisă pentru prima dată de Hentz, 1844. Conform Catalogue of Life specia Pardosa milvina nu are subspecii cunoscute.
Pardosa milvina là một loài nhện trong họ Lycosidae.[1]
Loài này thuộc chi Pardosa. Pardosa milvina được Nicholas Marcellus Hentz miêu tả năm 1844.
Pardosa milvina là một loài nhện trong họ Lycosidae.
Loài này thuộc chi Pardosa. Pardosa milvina được Nicholas Marcellus Hentz miêu tả năm 1844.
