Pardosa milvina

Last updated

Pardosa milvina
PardosaMilvina2.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Lycosidae
Genus: Pardosa
Species:
P. milvina
Binomial name
Pardosa milvina
(Hentz, 1844)
Shore spider, Pardosa milvina PardosaMilvina6.jpg
Shore spider, Pardosa milvina
Book of monsters (Page 40) BHL4428088 Book of monsters (Page 40) BHL4428088.jpg
Book of monsters (Page 40) BHL4428088

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.

Contents

Description

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]

Habitat and Distribution

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]

Diet

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]

Enemies

Predators

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]

Parasites

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]

Protective Behaviors

Detecting Predators

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]

Site Selection

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]

Leg Autotomy

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]

Mating

Airborne chemical communication

In addition to sexual pheromones on spider silk, researches have shown that Pardosa milvina possesses an airborne sexual communication capability.[ citation needed ] Researchers put unmated and mated females in pitfall traps and observe the behavior of adult males.[ citation needed ] 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.[ citation needed ] After statistical tests, the results are statistically significant.[ citation needed ] However, the chemical composition of sexual pheromones of P. milvina remains unknown.

Male Courtship

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]

Sexual Communication

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]

Parental care

Egg sacs

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]

Related Research Articles

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

Wolf spiders are members of the family Lycosidae. They are robust and agile hunters with excellent eyesight. They live mostly in solitude, hunt alone, and usually do not spin webs. Some are opportunistic hunters, pouncing upon prey as they find it or chasing it over short distances; others wait for passing prey in or near the mouth of a burrow.

<i>Latrodectus hesperus</i> Species of spider

Latrodectus hesperus, the western black widow spider or western widow, is a venomous spider species found in western regions of North America. The female's body is 14–16 mm in length and is black, often with an hourglass-shaped red mark on the lower abdomen. This "hourglass" mark can be yellow, and on rare occasions, white. The male of the species is around half this length and generally a tan color with lighter striping on the abdomen. The population was previously described as a subspecies of Latrodectus mactans and it is closely related to the northern species Latrodectus variolus. The species, as with others of the genus, build irregular or "messy" webs: unlike the spiral webs or the tunnel-shaped webs of other spiders, the strands of a Latrodectus web have no apparent organization.

<i>Phidippus audax</i> Species of arachnid (type of jumping spider)

Phidippus audax, the bold jumper or bold jumping spider, is a common species of spider belonging to the genus Phidippus, a group of jumping spiders easily identified by their large eyes and their iridescent chelicerae. Like all jumping spiders, they have excellent stereoscopic vision that aids them in stalking prey and facilitates visual communication with potential mates during courting. Bold jumping spiders are native to North America and have been introduced to Hawaii, Nicobar Islands, Azores, and the Netherlands. They are typically black with a distinct white triangle on their abdomen.

<i>Theridion grallator</i> Species of spider in the family Theridiidae

Theridion grallator, also known as the Hawaiian happy-face spider, is a spider in the family Theridiidae that resides on the Hawaiian Islands. T. grallator gets its vernacular name of "Hawaiian happy-face spider" from the unique patterns superimposed on its abdomen, specifically those that resemble a human smiling face. T. grallator is particularly notable because of its wide range of polymorphisms that may be studied to allow a better understanding of evolutionary mechanisms. In addition to the variety of color polymorphisms present, T. grallator demonstrates the interesting quality of diet-induced color change, in which its appearance temporarily changes as it metabolizes various food items.

<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>Zygiella x-notata</i> Species of spider

Zygiella x-notata, sometimes known as the missing sector orb weaver or the silver-sided sector spider, is a spider species in the family Araneidae. They are solitary spiders, residing in daily-spun orb webs. Z. x-notata is a member of the genus Zygiella, the orb-weaving spiders. The adult female is easily recognized by the characteristic leaf-like mark on her posterior opisthosoma, caudal to the yellow-brown cephalothorax.

<i>Phryganoporus candidus</i> Species of spider

Phryganoporus candidus, also known as the foliage web spider, is a small, subsocial jumping spider endemic to Australia. On average, they are 6–10 mm long and are a mottled brown colour, covered in silvery grey hair. They typically reside in arid and semi-arid locations, building their nests in various trees, bushes, and other plant-life. They have a mutualistic relationship with Acacia ligulata, and therefore prefer to build their nests in these trees.

<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. It is a trait observed in many arachnid orders and several insect and crustacean clades. Several hypotheses to explain this seemingly paradoxical behavior have been proposed. The adaptive foraging hypothesis, aggressive spillover hypothesis and mistaken identity hypothesis are among the proposed hypotheses to explain how sexual cannibalism evolved. 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.

<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.

<i>Phidippus clarus</i> Species of spider

Phidippus Clarus, also known as the Brilliant Jumping Spider, is a species of jumping spider found in old fields throughout eastern North America. It often waits upside down near the top of a plant, which may be useful for detecting prey, and then quickly jumps down before the prey can escape. The spider is one of 60 species in the genus Phidippus, and one of about 5,000 in the Salticidae, a family that accounts for about 10% of all spider species. P. clarus is a predator, mostly consuming insects, other spiders, and other terrestrial arthropods.

<i>Hogna carolinensis</i> Species of spider

Hogna carolinensis, commonly known as the Carolina wolf spider and giant wolf spider, is found across North America. It is the largest of the wolf spiders in North America, typically measuring at 18–20 mm for males and 22–35 mm for females.

<i>Pisaurina mira</i> Species of spider

Pisaurina mira, also known as the American nursery web spider, 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. 

<i>Tigrosa helluo</i> Species of spider

Tigrosa helluo is a species of spider belonging to the family Lycosidae, also known as wolf spiders. T. helluo was formerly known as Hogna helluo before differences between dorsal color patterns, habitat preferences, body structures, etc. were discovered. The species is native to the United States, Canada, and Mexico. It can be found across the eastern half of the United States, primarily in the Northeast and New England, and as far west as Nebraska and Kansas. T. helluo can be found in diverse habitats including woods, marshes, fields, and riparian areas. Typically, members of this species prefer to live in wetter areas as opposed to dry environments. Males tend to live for around a year and females will live for close to two years.

<i>Philodromus cespitum</i> Species of spider

Philodromus cespitum is a species of running crab spider in the family Philodromidae. It is found in North America, Europe, North Africa, and parts of the Middle East and Asia. P. cespitum is a foliage-dweller, and is the most abundant species found in European fruit orchards. It acts as a biological control by preying on orchard pests. P. cespitum is a diurnal ambush hunter and preys on aphids, insects, and occasionally competitor spider species. Males court females by tapping on the females’ bodies with their forelegs. They then insert a genital plug into the female during copulation. Unlike in many other spider species, subsequent males can mate with plugged females by removing part of the plug prior to copulation. Males discriminate among females based on virginity and plug size, and can determine these factors using the females’ draglines and plug samples.

<i>Tetragnatha versicolor</i> Species of spider

Tetragnatha versicolor is a species of long-jawed orb weaver in the spider family Tetragnathidae. It is found throughout North America, Canada, Central America, and Cuba, but are most common in the United States. T. versicolor is heavily concentrated in New England and the west coast in states like California and Washington. T. versicolor is considered a habitat generalist, and can thrive in many different environments. While they can be found in places like Grasslands, Wetlands, Forests, etc., they prefer dryer areas like normal trees and shrubs. Unlike other spiders in the genus Tetragnatha, T. versicolor will rarely reside near aquatic environments. T. versicolor will typically be colored dark yellow or pale orange and average around 5 mm for males and 6.5 mm for females in length, which is very small for a spider. They are much longer than they are wide, making them very distinct. In addition, T. versicolor can be distinguished from other spiders in Tetragnatha by the distinct separation of the anterior/posterior eyes and the appearance of their reproductive organs. As an orb weaver spider, T. versicolor creates a web to hunt for prey. It will wait at night for prey to stumble into its web and use vibrational signals throughout the web to sense trapped prey. In terms of mating behavior, T. versicolor lacks a distinct courting ritual and will mate with any others in the proximity. Mating behavior is heavily affected by female mating history. In terms of interactions with humans, the bite of T. versicolor is venomous, but not known to cause significant harm.

<i>Schizocosa ocreata</i> Species of spider

Schizocosa ocreata is a species of wolf spider in the family Lycosidae that is found in North America. The Schizocosa ocreata is a spider that is most commonly known as the “brush-legged wolf spider” because of their distinct dark-colored fur-like coverings around their legs. The S. ocreata are commonly found in North American states, usually in the middle and eastern United States.

<i>Argiope radon</i> Species of spider

Argiope radon is a species of orb web spider native to Australia. It is found in tropical areas of the Northern Territory, Western Australia and Queensland. It is commonly known as the Northern St Andrew's cross spider.

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

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

Schizocosa stridulans is a sibling species of S. ocreata and S. rovneri and is part of the wolf spider family. The name of the genus comes from the epigynum structure being lycosid and having a split T excavation. This spider is well-known for its specific leg ornamentation and courtship rituals and that is how it has been differentiated from its related species. The S. stridulans take systematic steps during its courtship ritual, which involves two independent signals. More specifically, female spiders will leave silk and pheromones to communicate that they are ready to mate.

<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. "Pardosa milvina Report". Integrated Taxonomic Information System. Retrieved 2019-09-25.
  2. "Pardosa milvina". GBIF. Retrieved 2019-09-25.
  3. "Pardosa milvina". NMBE World Spider Catalog. Retrieved 2019-09-25.
  4. Ross, Austin. "Pardosa milvina". Animal Diversity Web. Retrieved October 18, 2020.
  5. 1 2 3 Allard, Cora (2003). "Nematode and Dipteran Endoparasites of the Wolf Spider Pardosa milvina (Araneae, Lycosidae)". The Journal of Arachnology. 31 (1): 139–141. doi:10.1636/0161-8202(2003)031[0139:NADEOT]2.0.CO;2. JSTOR   3706323. S2CID   85583929 . Retrieved October 19, 2020.
  6. 1 2 3 4 5 Colancecco, Michael (Sep 2007). "Predation and Foraging Costs of Carrying Eggsacs of Different Mass in the Wolf Spider Pardosa milvina". Behaviour. 144 (9): 1003–1018. doi:10.1163/156853907781871888. JSTOR   4536495 . Retrieved October 19, 2020.
  7. 1 2 3 Rypstra, Ann (May–June 2016). "Cautious versus desperado males: predation risk affects courtship intensity but not female choice in a wolf spider". Behavioral Ecology. 27 (3): 876–885. doi: 10.1093/beheco/arv234 . Retrieved October 18, 2020.
  8. 1 2 3 4 Rypstra, Ann (May 2007). "Tradeoffs Involved in Site Selection and Foraging in a Wolf Spider: Effects of Substrate Structure and Predation Risk". Oikos. 116 (5): 853–863. doi:10.1111/j.0030-1299.2007.15622.x. JSTOR   40235128 . Retrieved October 19, 2020.
  9. James, Schmidt (2013). "Influence of prey availability on seasonal fluctuation in body condition in the wolf spider, Pardosa milvina (Araneae: Lycosidae)". The Journal of Arachnology. 41 (3): 400–403. doi:10.1636/P13-18. JSTOR   23610260. S2CID   84339564 . Retrieved October 19, 2020.
  10. 1 2 Brueseke, Michael (July 2001). "Leg Autotomy in the Wolf Spider Pardosa Milvina: A Common Phenomenon with Few Apparent Costs". The American Midland Naturalist. 146 (1): 153–160. doi:10.1674/0003-0031(2001)146[0153:LAITWS]2.0.CO;2. JSTOR   3083162. S2CID   36011351 . Retrieved October 19, 2020.
  11. 1 2 3 Sitvarin, Michael I. (2016). "The Wolf Spider Pardosa Milvina Detects Predator Threat Level Using Only Vibratory Cues". Behaviour. 153 (2): 159–173. doi:10.1163/1568539X-00003332. JSTOR   43955699 . Retrieved October 19, 2020.
  12. Khan, Rizwan (2015). "Female Pardosa milvina wolf spiders increase silk advertisements when in the presence of silk from courting males". The Journal of Arachnology. 43 (2): 168–173. doi:10.1636/J14-70. JSTOR   24717330. S2CID   135660813 . Retrieved October 19, 2020.