Marbled orb-weavers live in a large variety of habitats, including deciduous, mountain, and coniferous forests, as well as meadows, agricultural fields, orchards, peat bogs, along rivers, and rural and suburban areas. They can usually be found in shrubs and trees, often along the forest's edge, as well as in man-made structures such as mailboxes. (Edwards and Edwards, 1997; Enders, 1974; Esyunin and Laetin, 2009; Esyunin, et al., 2013; Levi, 1971; Opell and Hendricks, 2009; Pekar, 1999; Svaton and Pridavka, 2000)
Marbled orb-weavers have an oval-shaped abdomen; this sets them apart from other orb-weaver spiders. This species exhibits significant sexual dimorphism; females are much larger, they are 9.0 to 18.0 mm long and 2.3 to 4.5 mm wide, while males are 5.9 to 8.4 mm long and 2.3 to 3.6 mm wide. Marbled orb-weavers are polymorphic and show a wide variety of colors and patterns. There are two forms, the 'nominate marmoreus' form and the 'variation pyramidatus' form, which are found primarily in Europe. Both forms have light brown or orange carapaces and legs, while the ends of their legs are striped in white, clear, or black. The variation marmoreus form has a white, yellow, or orange abdomen, patterned in black, grey, and white. This abdominal pattern gives the species their common name, as they appear "marbled". The variation pyramidatus form has a paler abdomen, with a large dark brown irregular-shaped spot near the end of their abdomen. There are also intermediates between these two forms. Marbled orb-weavers have orange eggs that are about 1.15 mm wide. They can be distinguished from other members of genus Araneus, particularly shamrock orb-weavers, by differences in the spines on their tibiae. Spine patterns are mostly consistent within species. Marbled orb-weavers also have two types of tibial spines. Species of genus Araneus can also be identified by their genital characteristics. The embolus of male marbled orb-weavers is semi-circular, with flat hook-shaped lamellae. The embolus cap on virgin males can also be diagnostic of this species. The epigynum of females is also distinct, with the lamellae visible as large curved folds from the ventral side. (Carmichael, 1973; Enders, 1974; Levi, 1971; Opell and Bond, 2001; Roberts, 1985)
Eggs of marbled orb-weavers hatch in early spring after overwintering in egg sacs. Juveniles are present from spring to July, during which they molt through several instars, and eventually molt into reproductive adults. Adults mate in the summer and can be found from June to September. After mating and laying their egg sacs, adults die in the fall. (Fasola and Mogavero, 1995; Levi, 1971)
There is little information about the specific mating habits of marbled orb-weavers. Females of other Araneus species emit pheromones to attract mates; female marbled orb-weavers likely also emit pheromones. To court their mates, male members of genus Araneus spin a "mating-thread" across the female's web. The male moves towards the female across this thread, plucking and vibrating it, and the female approaches him. The male touches the front of the female's body with his legs, stroking her, until she hangs from the mating thread. The courtship habits of marbled orb-weavers are likely similar. Once courtship is complete, males embrace their female mates and transfer sperm by inserting their pedipalps. Virgin male marbled orb-weavers have the embolus on their palps capped. The capped is removed after the first mating. Males mate several times. Mating takes place in late summer. Other species of orb-weaving spiders exhibit sexual cannibalism, including European garden spiders, which are closely related and live in the same range as marbled orb-weavers. Females often eat their male mates at any point during the courtship and mating process. It is possible that marbled orb-weavers also exhibit sexual cannibalism; however, males mate multiple times and are noted to survive mating, so cannibalism may not be as significant in this species. (Elgar and Nash, 1988; Levi, 1971; Olive, 1982; Roggenbuck, et al., 2011)
After mating in late summer, female marbled orb-weavers lay their eggs in loose, fluffy egg sacs constructed from silk. In one report, an egg sac was 13 mm across and held 653 eggs. Eggs overwinter in these sacs and hatch the following spring. By July, the spiderlings molt into reproductive adults. (Enders, 1974; Fasola and Mogavero, 1995; Levi, 1971)
Marbled orb-weavers die after mating, so adults are not present to provide any sort of care when the spiderlings emerge the following spring. They do provide provisioning in the eggs, as well as construct an egg sac that likely provides some protection from the elements. (Levi, 1971)
Since spiderlings emerge from their egg sacs in the spring, mature into adults, and die in the fall after mating, marbled orb-weavers likely only live about 6 months. (Levi, 1971)
To build their orb-webs, marbled orb-weavers use the "second line" technique. A drag line of silk, produced from two silk glands in their abdomen is created as the spider descends from a substrate. At some point in the descent, a second line is created and attached to the main drag line. Farther down, the second line balloons out due to air currents. Up to several meters of the second line is pulled out from their spinnerets as they hang motionless. Often, spiders go back up the main drag line, reel in the second line and begin construction. An orb-web is typically composed of sticky threads arranged in spirals on non-viscous supporting threads. Marbled orb-weavers typically spin their web at the top of vegetation, in low shrubs, or tall grasses. They spin their web in the morning, and typically spend the day resting in a retreat off to the side of the web, in leaves or moss. During the night, spiders wait in the middle of the orb web for prey to get snared. Eggs overwinter in egg sacs and most adults die before winter begins, though some literature reports that marbled orb-weavers are active during the winter in colder regions, such as Sweden. (Eberhard, 1987; Gunnarsson, 1985; Levi, 1971; Opell and Hendricks, 2007; Opell, et al., 2011)
There is currently very little information available about the home range size of marbled orb-weavers.
Marbled orb-weavers have mechanoreceptors in the form of tactile hair sensilla on their tarsi that can detect not only movement or bending of the hair, but likely also the direction of the displacement. This allows spiders to perceive the environment around them through touch; they are also sensitive to air currents. Orb-spiders also have chemoreceptors on their tarsi that function in olfaction and chemical detection. Other spiders in genus Araneus use pheromones to attract mates. Female marbled orb-weavers also likely release airborne pheromones to communicate with and attract their mates. Touch is also used during mating for many other orb-weaver species, as the male courts the female by stroking her body with his legs. (Elgar and Nash, 1988; Foelix and Chuwang, 1973; Olive, 1982)
Marbled orb-weavers prey on many insect species. They construct orb-webs, which have sticky threads arranged spirally with non-sticky supporting threads. The non-viscous threads absorb the movement of the prey, while the viscous threads restrain the prey, which gives the spider time to locate, go to, and attack the prey. They mostly eat smaller insects, generally ranging from 0 to 4 mm, particularly from orders Orthoptera, Diptera, and Hymenoptera. One study found that a single marbled orb-weaver could catch about 14 prey insects per day, on average. (Japyassu and Caires, 2008; Opell and Hendricks, 2007; Opell, et al., 2011; Pasquet, 1984)
Many species of wasps prey on marbled orb-weavers. Some wasp species, including spider wasps (Batozonellus lacerticida) and blue mud daubers (Chalybion californicum), catch and paralyze marbled orb-weavers. The paralyzed spiders are placed in a burrow with a wasp egg, and when the egg hatches and the larvae feed on the available spider prey. Other wasp species, including organ pipe mud daubers (Trypoxylon politum) and white-trimmed black wasp (Episyron quinquenotatus), simply catch and feed on marbled orb-weavers. Birds are also predators; one noted predatory species are penduline tits (Remiz pendulinus) in Europe. (Endo and Endo, 1994; Kristofik, et al., 1993; Kurczewski and Kurczewski, 1968; Landes, et al., 1987; Rehnberg, 1987)
Many species of wasps prey on marbled orb-weavers, feeding as adults or using the spiders as a food supply for their offspring. Marbled orb-weavers are also prey to many species of birds. They are a significant insectivore and prey on the many different insect species caught in their web, particularly dipterids and hymenopterans. (Endo and Endo, 1994; Kurczewski and Kurczewski, 1968; Landes, et al., 1987; Rehnberg, 1987)
There are no known positive effects of marbled orb-weavers on humans.
There are no known adverse effects of marbled orb-weavers on humans.
Marbled orb-weavers have no special conservation status.
Angela Miner (author), Animal Diversity Web Staff, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
An animal that eats mainly insects or spiders.
fertilization takes place within the female's body
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
having more than one female as a mate at one time
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
breeding is confined to a particular season
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
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