Mastophora hutchinsoni

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American bolas spider
Mastophora hutchinsoni  (48448404301).jpg
Female
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Araneidae
Genus: Mastophora
Species:
M. hutchinsoni
Binomial name
Mastophora hutchinsoni
Gertsch, 1955

Mastophora hutchinsoni, also known as the American bolas spider, is a species of orb weaver in the genus Mastophora . The genus is distributed extensively throughout various subtropical geographical areas including Australia, South Africa, Oriental Asia, and the Americas and is not found in Europe. [1] [2] The hunting behavior of adult female M. hutchinsoni is unusual because they are bolas spiders. They mimic moth pheromones to attract male moths, and female M. hutchinsoni have evolved to alter their chemical release to target different moths. [3] They then capture their prey with a sticky drop on the end of a silk line, resembling a bolas. [4]

Contents

Description

The female spiders have a large spherical abdomen with a milky white base often covered in darker brown patterns and a smaller brown carapace. [2] There is a clear distinction between the two sexes as extreme sexual dimorphism results in much larger females. Although both sexes hatch with their cephalothorax range being around 0.5 mm, the female develops into a significantly larger specimen than her male counterpart. The size difference coheres with the divergence of their respective hunting behaviors. While female bolas spiders hang from a horizontal thread waiting to swing her bolas or sticky orb towards her nearby prey (typically moths), the males do not use a bolas but implement hunting tactics reminiscent of early-instar spiders. [5]

Population structure, speciation, and phylogeny

M. hutchinsoni are part of the Mastophora genus within the larger Araineida or orb-weaver family. They are in the Arthropoda phylum, the Arachnida class, and the Araneae order. [2] Originally stemming from normal orb weavers, the genus adopted an alternative web design (the bolas) and widely distributed throughout the world. [6]

Distribution and habitat

Distribution

Mastophora are widely distributed throughout the world in temperate climates except for Euro Asia and South Africa. The M. hutchinsoni primarily reside in the northeastern regions of North America near areas of a more temperate climate. The range of locations in North America are from Minnesota to New Hampshire.

Habitat

M. hutchinsoni primarily nest and feed in shrubs or short trees, where they hunt and build their webs. These spiders will often utilize nearby leaves and twigs as a location to place their egg sacs. [7] Due to the limited range of prey affected by the female’s aggressive mimicry technique, the predator frequently moves to different locations according to prey availability. They do so by riding a silken thread that travels with the direction of the wind.

Behavior

Diet and predation

Adult female diet

Lacinipolia renigera Lacinipolia renigera 1.jpg
Lacinipolia renigera

As a result of a highly specialized hunting technique that mimics the disparate chemical compositions of its prey, the hunting range for the M. hutchinsoni is limited to a couple families of male moths. The females typically hunt either Noctuidae moths consisting of the bristly cut-worm, bronzed cutworm, and smoky tetanolita or the bluegrass worm of the Pyralidae family during prime activity hours in the evening, which results in nocturnal hunting patterns. [6] [7]  In particular, the Lacinipolia renigera (bristly cut-worm) constitutes two-thirds of total prey biomass and, together with the Tetanolita mynesalis (smoky tetanolita), makes up to ninety percent of the overall diet of M. hutchinsoni. [3] Adult females will often capture more than one moth per night. [7]

Aggressive pheromone mimicry

Female M. hutchinsoni employ a specialized hunting tactic where they aggressively mimic the pheromones of moths to attract male moths near their bolas trap. Female moths produce a complex pheromone typically combining two compounds in a ratio specific to the species. This allows male moths to easily distinguish between mates of different species. The periods of activity for each moth are also different. For instance, the bristly cut-worm is active earlier in the night than the smoky tetanolita. Thus, the female spiders must adjust the level of chemicals produced to accommodate for different moths. [6] [8]

Spiderling diet

Instead of producing bolas like adult females to capture their prey, spiderlings remain motionless in the margins of leaves in shrubs or trees and wait to quickly ambush small flies that pass. In preparation for capture, the early-instar spiders extend both of their front legs which contain small bristles that aid in capture. These immature spiders also seem to attract male Psychoda using a mechanism near to or the same as aggressive chemical mimicry. [7] [8]

Adult male diet

The males do not construct a bolas to capture. Although females lose the strong bristles on their front legs after maturation, the males retain these features. Accordingly, it seems that they reserve hunting tactics similar to juvenile spiders. Thus, the male spiders have a similar diet to spiderlings--psychodid flies . [7] [8]

Webs

Bolas Web Design Bolas Spider - Mastophora phrynosoma hunting, Julie Metz Wetlands, Woodbridge, Virginia (24843011518).jpg
Bolas Web Design

Unlike many of the web designs constructed by its closely related species in the family of orb weavers, M. hutchinsoni do not form the typical two-dimensional orb web. Instead, the females primarily reside in a nearby leaf or plant while producing a single horizontal thread which they stay on and travel across during times of predation. At the terminal end, the spider forms an extremely adhesive orb which it quickly hurls in a circular pattern to capture flying prey. [1] [7] The bolas is much more efficient at capturing moths as it prevents the prey from escaping through shedding its scales--an escape mechanism that would otherwise work on typical orb webs. [3] If there is no prey captured after a short while, the Mastophora brings the orb back and consumes it--preparing to form another one to replace the former. Such behavior has been attributed to the short-term efficacy of the orb’s stickiness. Accordingly, after a single use of the bolas, the female must form another if intending to hunt more prey. [2]

Life cycle

Spiderlings will hatch during the spring. The rate of development between the two sexes will differ as males develop much more quickly than females. While the males fully develop during the summer months, the females mature around the fall season. [7] During this gap, the mature males often leave their webs and reside in the webs of developing females awaiting to mate. [5]

Eggs

Bolas Spider egg sac with eggs inside Bolas Spider egg sac with eggs inside - Mastophora phrynosoma, Julie Metz Wetlands, Woodbridge, Virginia.jpg
Bolas Spider egg sac with eggs inside

The egg sacs of the M. hutchinsoni are spherical in shape with an extended stem typically surrounded by multiple protective layers and an off-white silk. The globose vessels have a diameter around 8 mm while the connected stem extends up to thirty-six millimeters. The base of the egg is typically attached to either a branch of twig. [1]

Protective coloration

Considering the extreme sexual dimorphism resulting in a noticeably large size, M. Hutchinsoni adult females fashion a more cryptic coloration with a white palette and dark brown patterns. Meanwhile, the male bolas spiders are much smaller with reddish-brown hue. Moreover, the female’s large globular abdomen allows it to resemble bird droppings sitting on leaves. The bolas spider makes use of this resemblance as a defensive mechanism to avoid encounters with potential predators. [1] [2]

Physiology

Pheromone blends of moth species are unique and may interfere with each other resulting in reduced efficacy or failed mimicry. To accommodate such discrepancies, the bolas spider continuously produces a substandard blend of both pheromones elements and adjusts the amount of emission as time moves from one species’ zone of activity to another. [8]

Moth pheromone

The pheromone compositions are unique to their respective species of moth--this differentiation helps male moths recognize the correct mating partner. Accordingly, the pheromones usually contain a blend of multiple chemical components. The bristly cutworm which makes up the majority of the diet of the M. hutchinsoni emits a pheromone with (Z)-9-tetradecenyl acetate (Z9-14: Ac) and 3.8 percent (Z,E)-9,12-tetradecenyl acetate (ZE-9, 12-14: Ac). M. Meanwhile, Tetanolita mynesalis, the other main food source, emits a blend with two parts (3Z, 9Z)-(6S, 7R)-epoxy heneocosadiene and one part (3Z, 6Z, 9Z)-heneicosatrience). Nephelodes minians (the bronzed cutworm) holds a chemical composition consisting of a blend of (Z)-11-hexadecenal and (Z)-11- hexadecenyl acetate. M. hutchinsoni is not only able to synthesize the components of different chemical blends but also mimic the exact ratios. [3] [9]

Wing vibration

Despite being nocturnal hunters, M. hutchinsoni have poor vision and rather rely on prey wing vibrations to trigger bolas construction. [2] The female has tiny hairs on her legs that are sensitive to such vibrations. Using a cabbage looper moth as an intermediate wing vibration rate for the L.renigera and T. mynelasis, the bolas spider constructs a bolas a few minutes after being exposed to wing vibrations. [6]

Bites to animals

The M. hutchinsoni females produce venom to fatally impair her prey. After the M. hutchinsoni successfully attracts and traps the moth prey on the sticky bolas, the spider quickly reels the moth to herself, paralyzes the moth with a venomous bite, and wraps the prey in an envelope of silk to preserve the meal. [6] The venom of Mastophora is not recorded to be dangerous toward humans or large animals. [1]

Related Research Articles

<i>Celaenia excavata</i> Species of spider

Celaenia excavata, the bird dropping spider of Australia and New Zealand, derives its name from mimicking bird droppings to avoid predators, mainly birds. However, there are other species of spider that resemble bird droppings, for example species of Mastophora.

Bolas spider Group of spiders that capture prey with a bolas

A bolas spider is a member of the orb-weaver spider that, instead of spinning a typical orb web, hunts by using one or more sticky "capture blobs" on the end of a silk line, known as a "bolas". By swinging the bolas at flying male moths or moth flies nearby, the spider may snag its prey rather like a fisherman snagging a fish on a hook. Because of this, they are also called angling or fishing spiders. The prey is lured to the spider by the production of up to three sex pheromone-analogues.

A semiochemical, from the Greek σημεῖον (semeion), meaning "signal", is a chemical substance or mixture released by an organism that affects the behaviors of other individuals. Semiochemical communication can be divided into two broad classes: communication between individuals of the same species (intraspecific) or communication between different species (interspecific).

Ant mimicry Animals that resemble ants

Ant mimicry or myrmecomorphy is mimicry of ants by other organisms. Ants are abundant all over the world, and potential predators that rely on vision to identify their prey, such as birds and wasps, normally avoid them, because they are either unpalatable or aggressive. Spiders are the most common ant mimics. Additionally, some arthropods mimic ants to escape predation, while others mimic ants anatomically and behaviourally to hunt ants in aggressive mimicry. Ant mimicry has existed almost as long as ants themselves; the earliest ant mimics in the fossil record appear in the mid Cretaceous alongside the earliest ants. Indeed one of the earliest, Burmomyrma, was initially classified as an ant.

<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.

Spider behavior refers to the range of behaviors and activities performed by spiders. Spiders are air-breathing arthropods that have eight legs and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms which is reflected in their large diversity of behavior.

Aggressive mimicry Deceptive mimicry of a harmless species by a predator

Aggressive mimicry is a form of mimicry in which predators, parasites, or parasitoids share similar signals, using a harmless model, allowing them to avoid being correctly identified by their prey or host. Zoologists have repeatedly compared this strategy to a wolf in sheep's clothing. In its broadest sense, aggressive mimicry could include various types of exploitation, as when an orchid exploits a male insect by mimicking a sexually receptive female, but will here be restricted to forms of exploitation involving feeding. An alternative term Peckhamian mimicry has been suggested, but is seldom used. For example, indigenous Australians who dress up as and imitate kangaroos when hunting would not be considered aggressive mimics, nor would a human angler, though they are undoubtedly practising self-decoration camouflage. Treated separately is molecular mimicry, which shares some similarity; for instance a virus may mimic the molecular properties of its host, allowing it access to its cells.

Chemical mimicry

Chemical mimicry is a type of biological mimicry, involving the use of chemicals to dupe an operator. A chemical mimic dupes an operator by showing an adaptive chemical resemblance to an object of its environment and as a consequence receives selective advantage. In all cases of chemical mimicry it has been found that the mimicking species is the only species to benefit from the reaction with either costs or no effect on the duped species. This is by adapting to produce chemicals that will cause a desirable behavioural reaction in the species being deceived and a selective advantage to the mimic. Chemical mimicry exists within many of the different forms of mimicry such as aggressive, protective, Batesian, and Müllerian mimicry and can involve a number of different senses. Mimicking semiochemicals, which cannot be seen, make up some of the most widely used forms of chemical mimicry and is therefore less apparent than more visual forms. As a result of this, this topic has been relatively neglected in research and literature. Two examples of organisms displaying chemical mimicry include the mimicking of Noctuid pheromones by bolas spiders in order to draw prey to the spider’s location and the duping of insects within their own nests by mimicking their odours in order to enter and hide within the nest undetected. It is important to note that in all forms of mimicry the mimicking organism is not conscious of the deceit used and does not act intentionally to trick other organisms.

Spider Order of arachnids

Spiders are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms. Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exceptions of air and sea colonization. As of August 2021, 49,623 spider species in 129 families have been recorded by taxonomists. However, there has been dissension within the scientific community as to how all these families should be classified, as evidenced by the over 20 different classifications that have been proposed since 1900.

<i>Mastophora</i> (spider) Genus of spiders

Mastophora, also known as bolas spiders, is a genus of orb-weaver spiders first described by E. L. Holmberg in 1876. They can be identified by a pair of lumps on the dorsal surface of the opisthosoma, though not all males will have these lumps.

Exechocentrus is a genus of Madagascan orb-weaver spiders first described by Eugène Simon in 1889. It is a bolas-using spider, capturing its prey with one or more sticky drops at the end of a single line of silk rather than in a web.

<i>Pasilobus</i> Genus of spiders

Pasilobus is a genus of orb-weaver spiders first described by Eugène Simon in 1895.

<i>Mastophora cornigera</i> Species of spider

Mastophora cornigera is a species of orb weaver in the spider family Araneidae. It is found in a range from the United States to Nicaragua. Like all known species of the genus Mastophora, adult females are bolas spiders, capturing their prey with one or more sticky drops at the end of a single line of silk rather than in a web. Males and juvenile females capture their prey directly with their legs.

<i>Mastophora bisaccata</i> Species of spider

Mastophora bisaccata is a species of orb weaver in the spider family Araneidae. It is also known as Mastaphora obesa. It is found in the United States and Mexico. Like all known species of the genus Mastophora, adult females are bolas spiders, capturing their prey with one or more sticky drops at the end of a single line of silk rather than in a web. Males and juvenile females capture their prey directly with their legs.

Mastophora yeargani is a species of orb weaver in the spider family Araneidae. It is found in the United States. Like all known species of the genus Mastophora, adult females are bolas spiders, capturing their prey with one or more sticky drops at the end of a single line of silk rather than in a web. Males and juvenile females capture their prey directly with their legs.

Cyrtarachninae Subfamily of spiders

Cyrtarachninae is a subfamily of spiders in the family Araneidae. The group has been circumscribed in several different ways. It originated as the group Cyrtarachneae, described by Eugène Simon in 1892. The group was later treated at different ranks: as a tribe, both under Simon's name and as Cyrtarachnini, and as the subfamily Cyrtarachninae. Circumscriptions have varied. The broadest circumscription, Cyrtarachninae sensu lato (s.l.), includes three of Simon's original groups, including the bolas spiders. Unlike most araneids, members of the subfamily do not construct orb webs, some not using webs at all to capture prey, some using one or more sticky drops on a single line, while others construct webs with few widely spaced non-spiral threads, some triangular. Many have been shown to attract prey by producing analogues of insect sex pheromones, particularly to attract male moths. Adult females may mimic snails, bird droppings and other objects, and so are able to remain exposed during the day time, capturing prey at night.

Mastophora extraordinaria is a species of spider in the orb-weaver spider family Araneidae. It is found in South America. Like some other species of the genus Mastophora, adult females resemble bird droppings. Mastophora species, including M. extraordinaria, are "bolas spiders" – adult females capture their prey by using a sticky drop on the end of a single line which they swing at the target, usually a male moth attracted by the release of an analogue of the attractant sex pheromone produced by the female moth. Juveniles and adult males do not use a bolas, catching prey with their legs alone.

Cladomelea akermani is a species of spider in the orb-weaver spider family Araneidae, found in South Africa. Cladomelea species, including C. akermani, are "bolas spiders" – adult females capture their prey by using a sticky drop on the end of a single line which they swing, usually catching male moths attracted by the release of an analogue of the attractant sex pheromone produced by the female moth. Juvenile and adult male bolas spiders do not use a bolas, catching prey with their legs alone.

Ordgarius monstrosus is a species of spider in the orb-weaver spider family Araneidae, found in Queensland, Australia. O. monstrosus is a bolas spider. Rather than using a web, adult females catch their prey by using a line with one or two sticky drops which they swing.

<i>Ordgarius sexspinosus</i> Species of spider

Ordgarius sexspinosus is a species of spider in the orb-weaver spider family Araneidae, found from India to Japan and Indonesia. O. monstrosus is a bolas spider. Rather than using a web, adult females catch their prey by using a line with one or two sticky drops which they swing.

References

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