Pelegrina arizonensis

Geographic Range

Pelegrina arizonensis is found in North America, and is often referenced in the Midwestern region, particularly by Minnesota. In a 1996 study of Minnesotan special interest jumping spiders, William J. Ehman and Barbara E. Boyd describe sampling 16 counties for the Minnesota Department of Natural Resources. Their findings indicate this species was present in 5 of the 16 sampled counties, and tended to follow spatial patterns indicating a preference for the northwest and southeast sections of the state. This was a follow-up study to a 1988 sample by Cutler et al. describing their presence in 5 eastern counties including: Sherburne, Wabasha, Winona, as well as Polk and Washington in 1996.

It is worth noting that, despite increasing pressures from such sources as human development and climate change, this species has been able to retain a presence in its recorded territory over multiple field samples, over multiple years. A study published by the Minnesota Department of Natural Resources in 2002 reported that their findings indicated P. arizonensis was found in two areas (Allison Savanna and Uncas Dunes SF) in two separate studies, with multiple field seasons between. This has good potential for this species moving into the future, and may indicate some resilience in their ability to tolerate ecological change. However, both of the referenced studies are dated; one was published in 1997, and the other in 2002, which indicates more research, and more up-to-date field samples, are needed to give a better indication of species health in these areas in the present, as a continued follow-up to existing data.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Pelegrina arizonensis was found in Agassiz Dunes TNC, Kellog-Weaver Dunes SNA, Lake Elmo County Nature Reserve, Uncas Dunes SNA and Whitewater Bluffs SNA (which constituted bluffs and floodplain) habitat. Reported habitat includes fields, dune and sandy-soil environments, and prairie. Sand prairie was also reported by other findings as being reliable habitat for this species (Cutler, 1995) including species presence at Kellog-Weaver Dunes SNA and Whitewater Wildlife Management Area. However, this species also has reported ties to big blue stem ( Andropogon gerardii ), and an oak savanna.

In the 1997 report, the authors report that this species was present at eight separate sites in six areas (mentioned above) which constituted prairie grasses, moss, dunes and sandy soil, and an old field location near a wetland. While the exact distance from the wetland is not specified in the report, it is interesting that the species is reported in relatively dry soil habitats (and subsequently, a different ecological community in comparison to a wetland) as well as in close relative proximity to a more water-rich community. Within these areas, it is also reported that the sex and age of the individuals sampled varied significantly. They found 21 total individuals, of which, 14 were female, 3 were male, and 4 were immature, indicating a sex discrepancy. This species was reported to have been found with an immature Sassacus papenhoei individual, at a floodplain area in Whitewater State Natural Area. The habitat was stated to be sandy soils, covered in grass and moss.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• savanna or grassland savanna or grassland

• Other Habitat Features
• agricultural agricultural

Physical Description

Pelegrina arizonensis is also known by the scientific name Metaphidippus arizonensis as reported by the Minnesota Department of Natural Resources, and it is a member of the Salticidae family, which indicates it is a jumping spider and has several of those habits in common with other members of its family. Physically, it is also called "grassland white-cheeked jumping spider" due to its coloration. This is a small species with a sooty-colored body typical of Pelegrina species. It has a unique coloration scheme, with vertical markings along the thoracic region and a lighter, ash-shaded arrow symbol along the carapace. For images accurately depicting scale, morphology and coloring, please see Hollenbeck (2018).

Salticidae species are easily identifiable by their morphology, as well as one of their habits: jumping, by which they receive their colloquial name. Jumping spiders are small, thick about the abdomen, with very large eyes (even in comparison to other Araneae species) and legs that are short in comparison to their body size. Curiously, males do exhibit a difference in morphology in comparison to females: their first pair of legs is larger than the other ones. Coloration can also shift into brown with white edges, and swirling white stripes down the center of their carapace.

The Minnesota Department of Natural Resources also describes two closely related species, which may be confused with Pelegrina arizonensis and which are described below for ease in identification. <<Pelegrina insignis>> and <<Pelegrina proterva>> are also alike in overall size, body shape, and character, and are also classified as jumping spiders. However, there are key coloration differences which allow the three to be held as distinct from one another. In the first case, Pelegrina insignis has a mostly brown body, with black spots along its length in distinct rows. In the second case, Pelegrina proterva is identified by a yellow-tinged body, and black spots along the abdomen which are stated to be tinged red in female members of the species.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently
• male more colorful
• sexes shaped differently

Development

Pelegrina arizonensis begins its life as an egg; each nest made by an adult consists of many eggs, though the exact number is not detailed in available literature. This egg slowly grows while the female parent keeps watch over the nest (MNDNR, 2019), and the result after hatching is a number of miniature adult specimens, which tend to be lighter in color than their adult counterparts (CSIRO, 2019). While species specific information regarding a timeline for this species is not yet available, typical timelines imply a period of 6-12 months on average for Araneae individuals (CSIRO, 2019). It is therefore reasonable to assume a similar timeline for this species, though it may be shorter; as a Minnesotan species, this spider has to survive through or otherwise adapt to the often harsh climatic conditions. Minnesota has a true winter, with significant snow fall and low temperatures often reaching into the negatives by tens of degrees, with windchill. It may be assumed that their lifespans are sped up relative to their less climatically-challenged counterparts, in order to more successfully deal with the reality of harsh winter conditions (when their food is not available, and their bodies have to adapt to different conditions).

It is also worth noting that in order to grow to their adult sizes, their physiology has to make changes as well. As is the case generally with spiders, this species has to molt in order to successfully move through its developmental stages. Meaning, as the spider grows, its body will eventually need to shed its hard exoskeleton, which has become ill-fitting, in order to grow a new one that will allow for further growth (CSIRO, 2019). After several of these molts, the spider will have reached its maximum size, and it will be mature enough to be sexually active and look for mates of its own, to begin the process again. The entire process from beginning to end may range from anywhere from half a year to a full year in developmental stages, however, considering the previously mentioned variables, it is likely that their lifecycle is closer to the half year mark than the full year. However, further information and elucidation is needed in order to specifically detail this species' development.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

This species follows a similar mating pattern to other jumping spiders, and many other spiders generally, though not much is known. Typically, males compete for female attention (MNDNR, 2019) through differences in coloration (such as brighter colors, often edging into iridescence). The male is relatively smaller than the female, and the physiology is such that the cephalothorax and/or the abdomen (CSIRO, 2019) is likely to display this bright coloration, as well as their front legs, and even their mouth parts (MNDNR, 2019). There has been some research done, indicating the potential for their acute eyes to be sensitive not only to color, but ultraviolet as well (MNDNR, 2019). It is relatively common for jumping spiders to also rely on secondary courtship rituals, beyond coloration, to attract a mate. One instance is the so-called courtship dance ritual, where the male of the species will take up physical movements, often in a rhythmic manner, in specific patterns in order to display for a female. These are often species-specific "dances" (MNDNR, 2019) that have wild variability between species and clades. There is also the potential for these spiders to produce some kind of auditory signal (MNDNR, 2019) with a tell-tale sound to attract the female, or otherwise display for her. This sound can range from buzzes to drumrolls (MNDNR, 2019) when amplified enough for the human ear to reliably detect (Castilho et al., 2018 also reports auditory signalling).

Pelegrina arizonensis males will actively search for females to display to, though there is no reported defense mechanisms regarding them. Rather, as is the case with many spiders, the males are at great risk when displaying to females. Even within the same species, males risk being cannibalized by females (Castilho et al., 2018), either during or after copulation. It follows that, if males accidentally display to females of a different species (which would be easy to do - bright coloration is typical of the males of Salticidae species, whereas females are colored more cryptically and are therefore more likely to be confused with others) the risk of being eaten, rather than successfully mating, increases (Bittel, 2017). Males may exhibit promiscuous behavior (Bittel, 2017) in their search for a mate, by displaying indiscriminately to every female spider they encounter. However, males that display this behavior are also increasing their chances of encountering an outside-species female that would attack and even eat them as is often the case with Araneae , as they also increase their chances of encountering an in-species female, which they might be able to mate with. Either way, the males are risking death by displaying to females in order to mate; even if they do successfully mate, their partner may kill and eat them anyway (Yong, 2016), ostensibly to gain calories needed for egg laying and guarding.

Members of Salticidae do not have a documented social structure; as is often the case with Araneae generally, other than during mating seasons, most individuals are solitary. They're also short-lived, and as the longest living reported member of Salticidae lived only 750 days (for females) in natural conditions (Bartos, 2005). This indicates that, while not exact, P. arizonensis is almost certainly shorter lived in wild conditions. This translates to one, maybe two, mating seasons for females, and for males (if they haven't been cannibalized).

• Mating System
• monogamous monogamous

Not much is known about this species specifically, however, there are details that are common among Salticidae individuals. For instance, this species has elaborate mating rituals, predominately performed by males. They include rhythmic movement, dances, and vibratory signals; as they are highly visual spiders, much of their communication and mating rituals involve that sense. Once mating has been completed, the female produces multiple eggs, which are then secreted into an egg sac for safe-keeping. The male is either killed or moves on to another female; the female will stay with the egg sac throughout gestation, protecting it from predators and damages wherever possible, until the young hatch.

• Key Reproductive Features
• semelparous semelparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Pelegrina arizonensis has limited involvement in the raising of young. Male individuals arguably face a great sacrifice - as their mate may devour them in the process of copulation, as an example of spider cannibalism - in the creation of young. However, this is not necessarily a given in their mating behavior. After copulation, males have nothing to do with offspring. Females create an egg sac that contains the young as they develop, which is then secreted into the nest-like structure that they create (MNDNR, 2019) for protection. During this time, the eggs are protected by the female, until such a time as they hatch, producing young spiders. These young are virtually mini-adults, however, it is reported (MNDNR, 2019) that it is not uncommon for the young to stay with their female parent after hatching for an unspecified period of time. This would be in preparation to beginning life as isolated individuals, when they are able to properly and successfully hunt for themselves. No reports of stereotypical altricial care (such as food procurement, lessons in hunting/other necessary skills, etc.) are reported. Young will mature quickly, as the species has a relatively short lifespan, and will fledge relatively soon after hatching. Specific timelines are not available for this species, though it is inferred that the young would follow similar growing patterns to other spiders, i.e., the egg-adult span ranging from anywhere between 9-12 months, and sexual maturity occurring after several molts (which allows for growth) (CSIRO, 2019).

• Parental Investment
• precocial precocial
• female parental care female parental care
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • female
• pre-weaning/fledging
  • protecting
    • female
• pre-independence
  • protecting
    • female
• post-independence association with parents

Lifespan/Longevity

Exact lifespans for this species are not documented, however, some general trends may be inferred based on related species also classified under Salticidae . For instance, Yllenus arenarius has a sexual disparity in longevity (720 days for males, versus 750 days for female, inferencially due to reproductive mortality discrepancies) however, in natural settings, the longest documented time span is approximately 750 days. As another member of Salticidae , this species is stated by Bartos (2005) to be the longest lived member of Salticidae . Therefore, it is arguable that P. arizonensis has an close-to-equal or lesser lifespan. Typically, this species is not kept in captivity, and little information is available about such conditions. However, it is likely that major limiting conditions differ for males as opposed to females of this species. As previously stated, males are at greater risk of mortal injury/cannibalism during mating, which would greatly reduce their average lifespan. Females have greater calorie input (egg production and limited guarding behavior, as well as nest creation, upkeep and management) which may reduce their fitness. There is a need for greater elucidation on this topic in regards to P. arizonensis , as little information exists, and most is strongly tied towards other species or genera. Castilho et al. (2018) reports that most information on Salticidae is focused around Habronattus and Phidippus species.

Behavior

This species is predominately solitary; while highly communicative, these behaviors are strongly linked to mating behavior and are primarily exhibited by males of the species. They are otherwise thought to be solitary in nature, and no evidence exists to imply that they congregate in groups. Outside of this mating behavior, they are stated to be very curious, and will pivot in order to watch other organisms nearby. Interestingly, where many spider species will flee from a human's approach, Salticidae individuals, and this species particularly, are noted to stand their ground and watch the approach with some interest. Notably, their characteristic jumping motions are primarily for feeding, rather than communication.

• Key Behaviors
• terricolous
• saltatorial saltatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• hibernation hibernation
• solitary solitary
• territorial territorial

Home Range

Pelegrina arizonensis lives primarily in native Minnesota forb and grasses, particularly those associated with prairie and savanna habitats (MNDNR, 2019). However, individuals of this species may choose singular or small patches of desirable vegetation in order to build their characteristic retreats (MNDNR, 2019) which they will defend, and some may spend time on the ground. Due to their heavy reliance on visual acuity for hunting and habitat perception, much of their activity occurs during the daylight hours, when conditions for this are best. They tend to avoid rainy/foggy, or otherwise low-visibility conditions, preferring to stay within their retreats during these times (MNDNR, 2019). As is the case with many spiders, they are not active during the winter, and will pass the cold season in Minnesota in a state of torpor.

Communication and Perception

This species is highly adapted to visual perception; they have multiple sets of eyes, with one primary set that serves as their primary sensory input. They are highly communicative and curious animals: when faced with other species, including humans (which have a great, and seemingly intimidating, size discrepancy) they will pivot and watch, intrigued (MNDNR, 2019). They appear to enjoy watching others, and will often refuse to back up or flee, preferring to move to the best observatory vantage point. They are even reported to advance on organisms much larger than themselves, including humans (MNDNR, 2019) unlike many others, which will flee. They also have complex and fascinating communicative means between members of their own species, which may even bleed over to attempts at communication (and even attempting wooing) of other species.

Pelegrina arizonensis displays intense, and complex, mating communications. They communicate via little dances, whose steps include bobbing, body-part specific twitching (such as abdominal, leg, or even mouth parts), side steps, and zig-zagging around (MNDNR, 2019). They also rely on colors, including potentially color coding specific body parts in bright shades (specifically for the males; females are more muted in coloration, and tend to be larger).

• Communication Channels
• visual visual
• acoustic acoustic

• Other Communication Modes
• vibrations vibrations

• Perception Channels
• visual visual
• ultraviolet
• tactile tactile
• acoustic acoustic
• vibrations vibrations

Food Habits

As an Araneae species, Pelegrina arizonensis is a carnivore and an active hunter. Where many other species of spider are known for spinning intricate, attractive, and often ingenious webs in order to ensnare their prey via tacky threads, Salticidae individuals are known for their more "hands-on" hunting techniques. It is worth mentioning that, while not common, there are reports that spiders, and Salticidae specifically, may rely on atypical predatory behavior. For instance, Ross states (2008) that there are indications that some members of Araneae may eat pollen, and he even relates a sighting of a relative of this species devouring an earthworm. Earthworms are not considered typical prey for jumping spiders, who tend to target other insects and even other spiders for their dietary requirements. The reported species from Ross (2008) was not P. arizonensis , but rather P. undatus , which is a relative within the jumping spider designation. While not the same species, this report does indicate that it is possible, and not unheard of, for jumping spiders to prey on worms.

Curiously, this species is able, through specialized morphology, to take advantage of superior eye-sight and their ability to jump to actively pursue, kill, and devour their prey items. With four sets of acute eyes, one set of which is particularly large (MNDNR, 2019), even for spiders. That same set of large eyes is focused forward, and allows them to have better binocular vision, and even allows for accurately determining distances for a wide range of objects/individuals of interest (MNDNR, 2019), potentially even at 30 feet away. This is of great use when they stalk their prey; it allows them to, rather than rely on spinning webs to ensnare prey that comes to them, to seek out and determine easy prey to devour. It is of note, they will delay an outright attack, choosing instead to carefully stalk, before exhibiting their characteristic jumping behavior in order to launch themselves towards their food (MDNDR, 2019). They can, however, also steal food that is trapped in other spiders' webs, and are therefore opportunistic to some degree. It is also worth highlighting that many spiders hunt at night (CSIRO, 2019) but due to their highly visual predatory habit, this species hunts primarily during the day when visual acuity will be at its highest (MNDNR, 2019). They also tend to avoid hunting during overcast and/or rainy weather, preferring to stay within webbed nest-like structures built into spaces in native forb species (MNDNR, 2019).

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • vermivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

Predation

This species has one primary anti-predator adaptation, and that is it's ability to jump. While this behavior is certainly utilized in predation (so that it can catch, and consume, it's own prey items) it also serves as an advantageous ability, allowing them to spring away from any predators that attempt to eat them. They are, after all, relatively small spiders, and face threats of consumption from one another, as well as other spider species, which are acknowledged to rely on cannibalism where convenient. Therefore, the ability to move quickly out of range of others' webs, sticky-traps, and fangs is not to be understated. They are also able to quickly return to their safe-places (their characteristic dens, hidden in foliage) to escape any hungry eyes.

Ecosystem Roles

As is the case with all spiders, this species plays a significant role in insect control. They consume insects that may otherwise cause ecological or human-centric damage, and serve as pest controls to keep problematic species (such as gnats, mosquitoes, and other undesirables) in check. This serves to keep both the spider populations healthy, as well as the prey species (which, by definition, require some ecological controls to keep their populations under check), and help keep habitat in more advantageous condition for human visitation. Research is not available fully detailing the extent of their relationships with other species, however, they do have an acknowledged preference for building their retreats in native prairie plants, and can therefore be said to have a relationship with these plants. Specifically, the Minnesota DNR (2019) relays that the females are particularly choosy, preferring native forb species, whose capsules and heads are then utilized for den creation, safety, and reproduction (as this is where the egg sac is kept for safe-guarding during gestation).

Economic Importance for Humans: Positive

There are certainly those who question the importance of spiders; they are, after all, one of the more common phobias. However, they are extremely important for humans, and this species is no different. Jumping spiders, and Pelegrina arizonensis particularly, provide significant ecological benefits for humans. While the knowledge base of this species would benefit from increased study, to further detail their relationships with prairie forbs and other prairie natives, it is clear that, at the very least, they provide pest relief. They utilize their characteristic jumping behavior in order to catch insects at a significant pace, which aids in keeping insect populations in a manageable order. These insects could otherwise cause damage to crops and natural areas, and may act as human pests (potentially even serving as disease vectors, such as mosquitoes).

They are naturally curious and charismatic, and may serve as education ambassadors, both for prairie conservation, and as an introduction to spiders (ecosystem roles, biology and physiology, for example). This species is acknowledged to, not only pivot to face humans, but even continue forward to meet them. This behavior, coupled with their characteristic jumping behavior, and highly communicative nature make them ideal spider ambassadors for people with spider phobias, as well as small children. They also have unexplored ties with prairie plants that are arguably worth further elucidation, and may be good representatives for prairie conservation.

• Positive Impacts
• research and education
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Pelegrina arizonensis on humans.

Conservation Status

Pelegrina arizonensis is not listed on any of the stated resources for identifying a species in danger, however, the Minnesota Department of Natural Resources has listed it as a species of special concern and it has stayed at this listing since 1996. As a species commonly associated with dry prairies, or dry savannas, this species is also in danger of fire as one of the integral management techniques for these areas. It is also important to note that Minnesota has lost the vast majority of this habitat, which has adverse effects on a menagerie of species. This is particularly true of prairie species, as prairie territory, which is estimated to have been at 18 million acres in 1860, has lost the majority of this territory, and stands at only ~236,000 acres as of 2015. This drastic loss of territory, including the resources, space, and species individuals certainly had to have just as drastic an adverse affect on Pelegrina arizonensis . However, this is difficult to reliably quantify due to relatively little available research and literature.

Other Comments

Salticidae is a taxa that would significantly benefit from increased diverse representation in research; this is particularly true of Pelegrina arizonensis . These jumping spiders are minute, but highly important, members of the greater Minnesotan ecological system. It is of the author's opinion that increased importance ought to be given to these organisms, to increase the depth of knowledge available to the scientific community and the general public.

Additional Links

Encyclopedia of Life

Contributors

Ainsley Peterson (author), Minnesota State University Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Bartos, M. 2005. The Life History of Yllenus arenarius (Araneae, Salticidae): Evidence for Sympatric Populations Isolated by the Year of Maturation. The Journal of Arachnology , 33: 214-221. Accessed April 17, 2019 at https://www.jstor.org/stable/4129818?Search=yes&resultItemClick=true&searchText=salticidae&searchText=life&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3Dsalticidae%2Blife&ab_segments=0%2Fdefault-2%2Fcontrol&refreqid=search%3Af5f95bb9a7a5c7732955f360e57264e5&seq=1#metadata_info_tab_contents .

Bittel, J. 2017. "For Jumping Spiders, Choosing the Wrong Mate Turns Deadly" (On-line). National Geographic. Accessed April 17, 2019 at https://news.nationalgeographic.com/2017/05/jumping-spider-courtship-dance-cannibalism/ .

CSIRO, 2019. "Araneae: spiders" (On-line). Commonwealth Scientific and Industrial Research Organization. Accessed March 27, 2019 at http://www.ento.csiro.au/education/allies/araneae.html .

Castilho, L., M. Andrade, R. Macedo. 2018. Mating and egg-laying behavior of Hasarius adansoni (Araneae: Salticidae) and the influence of sexual selection. The Journal of Arachnology , 46: 398-403. Accessed April 17, 2019 at https://bioone.org/journals/The-Journal-of-Arachnology/volume-46/issue-3/JoA-S-16-091.1/Mating-and-egg-laying-behavior-of-iHasarius-adansoni-i-Araneae/10.1636/JoA-S-16-091.1.full .

Department of Entomology, 2019. "Species Pelegrina insignis" (On-line). Bug Guide. Accessed March 27, 2019 at https://bugguide.net/node/view/723412/bgimage .

Department of Entomology, 2019. "Species Pelegrina proterva" (On-line). Bug Guide. Accessed March 27, 2019 at https://bugguide.net/node/view/6783 .

Ehmann, W., B. Boyd. 1997. "Surveys for Proposed Special Concern Jumping Spiders of Minnesota" (On-line pdf). Accessed March 27, 2019 at https://files.dnr.state.mn.us/eco/nongame/projects/consgrant_reports/1998/1998_ehmann.pdf .

Ehmann, W. 2002. "Conservation Biology of Special Concern Jumping Spiders (Araneae: Salticidae) of Minnesota" (On-line). Accessed March 27, 2019 at https://files.dnr.state.mn.us/eco/nongame/projects/consgrant_reports/2002/2002_ehmann.pdf .

Hollenbeck, J. 2018. "Species Pelegrina arizonensis" (On-line image). Bug Guide. Accessed April 19, 2019 at https://bugguide.net/node/view/1578265 .

Maddison, W. 1995. "Pelegrina arizonensis (Peckham & Peckham 1901)" (On-line). Tree of Life Web Project. Accessed March 27, 2019 at http://tolweb.org/Pelegrina_arizonensis/5028 .

Minnesota Department of Natural Resources, 2019. "Pelegrina arizonensis" (On-line). Minnesota Department of Natural Resources. Accessed March 27, 2019 at https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=ILARAX8090 .

NatureServe, 2001. "Pelegrina arizonensis - Peckham & Peckham 1901" (On-line). An Online Encyclopedia of Life. Accessed March 27, 2019 at http://explorer.natureserve.org/servlet/NatureServe?searchName=Pelegrina+arizonensis .

Olson, D. 2015. "Preserved parcels offer glimpse of Minnesota gone by" (On-line). Minnesota Public Radio (MPR) News. Accessed March 27, 2019 at https://www.mprnews.org/story/2015/07/21/msv-prairies .

Ross, L. 2008. "A jumping spider feeding on an earthworm" (On-line). Peckhamia. Accessed April 17, 2019 at http://www.peckhamia.com/peckhamia/PECKHAMIA%2071.1.pdf .

Yong, E. 2016. "How Male Widow Spiders Avoid Being Cannibalized During Sex" (On-line). National Geographic. Accessed April 17, 2019 at https://news.nationalgeographic.com/2016/09/animals-spiders-black-widows-cannibals/ .