Why tarantula spiders are blue or green


This video is called Greenbottle Blue and Sazimai’s Blue Tarantula Comparison.

By Yale-NUS College in the USA:

Scientists discover why tarantulas come in vivid blues and greens

September 24, 2020

Summary: Researchers find support for new hypotheses: that tarantulas‘ vibrant blue colors may be used to communicate between potential mates, while green coloration confers the ability to conceal among foliage. Their research also suggests that tarantulas are not as color-blind as previously believed, and that these arachnids may be able to perceive the bright blue tones on their bodies.

Why are some tarantulas so vividly coloured? Scientists have puzzled over why these large, hairy spiders, active primarily during the evening and at night-time, would sport such vibrant blue and green colouration — especially as they were long thought to be unable to differentiate between colours, let alone possess true colour vision.

In a recent study, researchers from Yale-NUS College and Carnegie Mellon University (CMU) find support for new hypotheses: that these vibrant blue colours may be used to communicate between potential mates, while green colouration confers the ability to conceal among foliage. Their research also suggests that tarantulas are not as colour-blind as previously believed, and that these arachnids may be able to perceive the bright blue tones on their bodies. The study was published in Proceedings of the Royal Society B on 23 September, and is featured on the front cover of the current (30 September 2020) issue.

The research was jointly led by Dr Saoirse Foley from CMU, and Dr Vinod Kumar Saranathan, in collaboration with Dr William Piel, both from the Division of Science at Yale-NUS College. To understand the evolutionary basis of tarantula colouration, they surveyed the bodily expression of various opsins (light-sensitive proteins usually found in animal eyes) in tarantulas. They found, contrary to current assumptions, that most tarantulas have nearly an entire complement of opsins that are normally expressed in day-active spiders with good colour vision, such as the Peacock Spider.

These findings suggest that tarantulas, long thought to be colour-blind, can perceive the bright blue colours of other tarantulas. Using comparative phylogenetic analyses, the team reconstructed the colours of 110 million-year-old tarantula ancestors and found that they were most likely blue. They further found that blue colouration does not correlate with the ability to urticate or stridulate — both common defence mechanisms — suggesting that it did not evolve as a means of deterring predators, but might instead be a means of attracting potential mates.

The team also found that the evolution of green colouration appears to depend on whether the species in question is arboreal (tree-dwelling), suggesting that this colour likely functions in camouflage.

“While the precise function of blueness remains unclear, our results suggest that tarantulas may be able to see these blue displays, so mate choice is a likely potential explanation. We have set an impetus for future projects to include a behavioural element to fully explore these hypotheses, and it is very exciting to consider how further studies will build upon our results,” said Dr Foley.

The team’s survey of the presence of blue and green colouration across tarantulas turned up more interesting results. They found that the blue colouration has been lost more frequently than it is gained across tarantulas. The losses are mainly in species living in the Americas and Oceania, while many of the gains are in the Old World (European, Asian, and African) species. They also found that green colouration has evolved only a few times, but never lost.

“Our finding that blueness was lost multiple times in the New World, while regained in the Old, is very intriguing. This leaves several fascinating avenues for future research, when considering how the ecological pressures in the New and the Old Worlds vary,” said Dr Saranathan. “For instance, one hypothesis would be differences in the light environments of the habitats between the New and the Old World, which can affect how these colours might be perceived, if indeed they can be, as our results suggest.”

New spider species discovered in Colombia


This 21 September 2020 video is called New species of spider discovered – Ocrepeira klamt.

From the Universität Bayreuth in Germany:

A new species of spider

September 16, 2020

During a research stay in the highlands of Colombia conducted as part of her doctorate, Charlotte Hopfe, PhD student under the supervision of Prof. Dr. Thomas Scheibel at the Biomaterials research group at the University of Bayreuth, has discovered and zoologically described a new species of spider. The previously unknown arachnids are native to the central cordillera, not far from the Pacific coast, at an altitude of over 3,500 meters above sea-level. In the magazine PLOS ONE, the scientist from Bayreuth presents the spider she has called Ocrepeira klamt.

“I chose the zoological name Ocrepeira klamt in honour of Ulrike Klamt, my German teacher at high school. The enthusiasm with which she pursues her profession and the interest she shows in her students and in literature are an inspiration to me,” says Charlotte Hopfe.

The cordillera in Colombia is famous for its unusually large variety of species. The habitats of these species are distributed at altitudes with very different climatic conditions, vegetation, and ecosystems. The Bayreuth researcher has collected and zoologically determined specimens of more than 100 species of spider in these habitats. In doing so, she was mainly in a region that has only been accessible to researchers since the end of civil war in Colombia in 2016. She discovered the new spider, which differs from related species in the striking structure of its reproductive organs, at altitudes of over 3,500 meters above sea-level. In the identification of this and many other spider specimens, Hopfe received valuable support from researchers at Universidad del Valle in Cali, Colombia, with which the University of Bayreuth has a research cooperation. Colombia has been identified as a priority country in the internationalization strategy of the University of Bayreuth, which is why it maintains close connections with several Colombian universities.

The study of spiders from regions of such various huge climatic and ecological variety may also offer a chance to find answers to two as yet unexplored questions. It is not yet known whether temperatures, precipitation, or other climatic factors influence the evolution of spiders, or the properties of their silk. For example, is the proportion of species with extremely elastic silk in the lowland rainforest higher than in the semi-desert? And it is also still unclear whether the properties of the silk produced by a species of spider are modified by climatic factors. Would a spider living in the high mountains, such as Ocrepeira klamt, produce the same silk if it were native to a much lower region of the cordillera? The answer to these questions could provide important clues as to the conditions under which unusual spider silks develop.

Along similar lines, it would also be interesting to explore whether there are spider silk proteins which, due to their properties, are even more suitable for certain applications in biomedicine and biotechnology than silk proteins currently known. “The greater the variety of spider silks whose structures and properties we know, the greater the potential to optimize existing biomaterials and to develop new types of biomaterials on the basis of silk proteins,” Hopfe explains.

Charlotte Hopfe’s research was funded by the German Academic Exchange Service and the German Academic Scholarship Foundation.

Slingshot spiders in Amazon rainforests


This June 2017 video says about itself:

Spider Shoots 25 Metre Web | The Hunt | BBC Earth

Which marvel of nature can build a 25m orb web with a silk that ranks as the world’s toughest natural fibre? The answer is the Darwin’s bark spider.

From the Georgia Institute of Technology in the USA:

Flies and mosquitoes beware, here comes the slingshot spider

August 17, 2020

Running into an unseen spiderweb in the woods can be scary enough, but what if you had to worry about a spiderweb — and the spider — being catapulted at you? That’s what happens to insects in the Amazon rain forests of Peru, where a tiny slingshot spider launches a web — and itself — to catch unsuspecting flies and mosquitoes.

Researchers at the Georgia Institute of Technology have produced what may be the first kinematic study of how this amazing arachnid stores enough energy to produce acceleration of 1,300 meters/second2 — 100 times the acceleration of a cheetah. That acceleration produces velocities of 4 meters per second and subjects the spider to forces of approximately 130 Gs, more than 10 times what fighter pilots can withstand without blacking out.

The Peruvian spider and its cousins stand out among arachnids for their ability to make external tools — in this case, their webs — and use them as springs to create ultrafast motion. Their ability to hold a ready-to-launch spring for hours while waiting for an approaching mosquito suggests yet another amazing tool: a latch mechanism to release the spring.

“Unlike frogs, crickets, or grasshoppers, the slingshot spider is not relying on its muscles to jump really quickly,” said Saad Bhamla, an assistant professor in Georgia Tech’s School of Chemical and Biomolecular Engineering who studies ultrafast organisms. “When it weaves a new web every night, the spider creates a complex, three-dimensional spring. If you compare this natural silk spring to carbon nanotubes or other human-made materials in terms of power density or energy density, it is orders of magnitude more powerful.”

The study, supported by the National Science Foundation and National Geographic Society Foundation, was published August 17 in the journal Current Biology. Understanding how web silk stores energy could potentially provide new sources of power for tiny robots and other devices, and lead to new applications for the robust material, the researchers say.

Slingshot spiders, known by the scientific genus name Theridiosomatid, build three-dimensional conical webs with a tension line attached to the center. The Peruvian member of that spider family, which is about 1 millimeter in length, pulls the tension line with its front legs to stretch the structure while holding on to the web with its rear legs. When it senses a meal within range, the spider launches the web and itself toward a fly or mosquito.

If the launch is successful, the spider quickly wraps its meal in silk. If the spider misses, it simply pulls the tension line to reset the web for the next opportunity.

“We think this approach probably gives the spider the advantage of speed and surprise, and perhaps even the effect of stunning the prey,” noted Symone Alexander, a postdoctoral researcher in Bhamla’s lab. “The spiders are tiny, and they are going after fast-flying insects that are larger than they are. To catch one, you must be much, much faster than they are.”

Slingshot spiders were described in a 1932 publication, and more recently by Jonathan Coddington, now a senior research entomologist at the Smithsonian Institution. Bhamla has an interest in fast-moving but small organisms, so he and Alexander arranged a trip to study the catapulting creature using ultrafast cameras to measure and record the movement.

“We wanted to understand these ultrafast movements because they can force our perspective to change from thinking about cheetahs and falcons as the only fast animals,” Bhamla said. “There are many very small invertebrates that can achieve fast movement through unusual structures. We really wanted to understand how these spiders achieve that amazing acceleration.”

The researchers traveled six hours by boat from Puerto Maldonado to the Tambopata Research Center. There is no electricity in the area, so nights are very dark. “We looked up and saw a tiny red dot,” Bhamla recalled. “We were so far away from the nearest light that the dot turned out to be the planet Mars. We could also see the Milky Way so clearly.”

The intense darkness raises the question of how the spider senses its prey and determines where to aim itself. Bhamla believes it must be using an acoustic sensing technique, a theory supported by the way the researchers tricked the spider into launching its web: They simply snapped their fingers.

Beyond sensing in the dark, the researchers also wondered how the spider triggers release of the web. “If an insect gets within range, the spider releases a small bundle of silk that it has created by crawling along the tension line,” Alexander said. “Releasing the bundle controls how far the web flies. Both the spider and web are moving backward.”

Another mystery is how the spider patiently holds the web while waiting for food to fly by. Alexander and Bhamla estimated that stretching the web requires at least 200 dynes, a tremendous amount of energy for a tiny spider to generate. Holding that for hours could waste a lot of energy.

“Generating 200 dynes would produce tremendous forces on the tiny legs of the spider,” Bhamla said. “If the reward is a mosquito at the end of three hours, is that worth it? We think the spider must be using some kind of trick to lock its muscles like a latch so it doesn’t need to consume energy while waiting for hours.”

Beyond curiosity, why travel to Peru to study the creature? “The slingshot spider offers an example of active hunting instead of the passive, wait for an insect to collide into the web strategy, revealing a further new functionality of spider silk,” Bhamla said. “Before this, we hadn’t thought about using silk as a really powerful spring.”

Another unintended benefit is changing attitudes toward spiders. Prior to the study, Alexander admits she had a fear of spiders. Being surrounded by slingshot spiders in the Peruvian jungle — and seeing the amazing things they do — changed that.

“In the rainforest at night, if you shine your flashlight, you quickly see that you are completely surrounded by spiders,” she said. “In my house, we don’t kill spiders anymore. If they happen to be scary and in in the wrong place, we safely move them to another location.”

Alexander and Bhamla had hoped to return to Peru this summer, but those plans were cut short by the coronavirus. They’re eager to continue learning from the spider.

“Nature does a lot of things better than humans can do, and nature has been doing them for much longer,” she said. “Being out in the field gives you a different perspective, not only about what nature is doing, but also why that is necessary.”

This research was supported by the National Science Foundation (NSF) through award 1817334 and CAREER 1941933, by the National Geographic Foundation through NGS-57996R-19, and by the Eckert Postdoctoral Research Fellowship from the Georgia Tech School of Chemical and Biomolecular Engineering. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the funding organizations.

New spider, wasp, lizard species discoveries


This 1 July 2020 video is about a new spider species called after Joaquin Phoenix.

From the University of Turku in Finland:

New species described in 2020

July 1, 2020

It is estimated that 15 million different species live on our planet, but only 2 million of them are currently known to science. Discovering new species is important as it helps to protect them. Furthermore, new species can also produce compounds that could lead to the development of new medicine.

“Biodiversity is declining at an accelerating rate and, according to estimates, even a million organisms are in danger of becoming extinct in the next few decades. If we want to protect nature’s biodiversity as efficiently as possible, we have to discover as many species as we can,” says Professor of Biodiversity Research Ilari E. Sääksjärvi from the University of Turku, Finland.

Discovering new species enables, for example, studying their habits and defining their geographical distribution.

So far this year, the researchers of the Biodiversity Unit at the University of Turku have described 17 new spider species, 23 insects, one bristly millipede, and one monitor lizard. The new species have been discovered from the Amazon, Europe, India, the Middle East, and the Pacific islands. In addition to the species, the researchers have also described four new genera previously unknown to science.

The Amazing Beauty of Spiders

In one of the most recent studies from the Biodiversity Unit, Doctoral Candidate Alireza Zamani described a new spider species Loureedia phoenixi from Iran.

“The discovery was amazing as the new species belongs to the genus of velvet spiders, of which only few species have been known so far. They are very shy in their habits so discovering a new species was a great and welcome surprise. The species in this genus are amazingly beautiful and colourful so I wish this new discovery can make people understand the beauty and importance of spiders. We discovered the species from an area that is about 1,500 kilometres outside the known geographical distribution of the Loureedia genus,” describes Zamani.

Zamani and Sääksjärvi say that the Loureedia phoenixi spider was named after actor Joaquin Phoenix. The colourful pattern on its back resembles the face paint of the movie character Joker.

The researchers of the Biodiversity Unit have also described tropical parasitoid wasps belonging to the Acrotaphus and Hymenoepimecis genera. These wasps are parasitic on spiders and manipulate the host in complicated ways. The parasitoid wasp lays its egg on the spider and then manipulates it into spinning a special web instead of a normal web for catching prey. The wasp’s pupa nests safely inside this special web while developing into adulthood.

Species Discoveries Support Conservation Efforts

New discoveries increase our information about the history of species and can therefore affect their conservation in the future. A good example is the Varanus bennetti monitor lizard described this year, as the importance of the species’ conservation was concluded only after close field and laboratory studies.

“The monitor lizard species that was first considered an invasive species to Micronesia turned out to be two separate species native to the islands. We described one of these as new to science,” say researchers Valter Weijola and Varpu Vahtera who discovered the species.

Discovering, classifying, and describing a new species is a long process. New discoveries often require challenging field studies in remote places. Before conducting the field study, the researcher has to make sure that the required permits for collecting specimens and taking them out of the country are in order. The studies are conducted together with local scientists as often as possible.

After the field study, the other research work begins: the species is examined in a laboratory, described, named, and classified and then the research article is published in an international journal.

In the last few years, the Biodiversity Unit of the University of Turku has profiled itself especially in describing the biodiversity of unknown ecosystems. Each year, the unit describes dozens of new species which is a great amount even by international standards.

“Our goal is to discover new species and tell their story to the world. At the moment, we are in the process of describing even more new species and genera. Many of these animals live in areas that might transform or even disappear in the next few years. Describing new species to science is a race against the clock. We hope that our research draws people’s attention to the life of these unique species and thus promotes the conservation of biodiversity,” conclude Sääksjärvi and Zamani.

Global warming benefits Greenland wolf spiders


This 2019 video says about itself:

Arctic Wolf Spiders‘ Changing Diet May Help Keep Arctic Cool & Lessen Some Impacts of Global Warming

Ecologist Amanda Koltz has a special interest in climate change and spiders. Koltz said she chose to study Arctic wolf spiders because they’re fierce hunters and abundant, making them one of the most important predators in the tundra. Leaving her biology lab at Washington University in St. Louis, Koltz conducts her field research in Northern Alaska. Koltz and her team discovered that Arctic wolf spiders may buffer some of the effects of global warming by helping to ‘keep it cool’. Wolf spiders may play a role decreasing decomposition rates in a warming climate. As the Arctic warms, research shows wolf spiders may dine differently initiating a cascade of food web interactions that could potentially alleviate some impacts of global warming.

From Aarhus University in Denmark:

Spider baby boom in a warmer Arctic

June 25, 2020

Climate change leads to longer growing seasons in the Arctic. A new study, which has just been published in Proceedings of the Royal Society B, show that predators like wolf spiders respond to the changing conditions and have been able to produce two clutches of offspring during the short Arctic summer.

Arctic spiders are at the top of the food chain among invertebrates and are numerous on the Arctic tundra. They typically take several years to become adults, and only produce offspring [once].

But something is happening in the high north in these years. A lot, actually.

Climate change is more dramatic here than in no other place on Earth. The average temperature is increasing significantly and this affects the ecosystems.

Researchers have previously reported how plants bloom earlier and earlier in the season. There are also signs that species move farther north and up into the mountains.

A team of researchers led by senior researcher Toke T. Høye from the Arctic Research Centre and Department of Bioscience at Aarhus University has now shown that changes are also occurring in the reproduction of invertebrates.

For almost 20 years, researchers at the Zackenberg Research Station in north-eastern Greenland have caught wolf spiders as part of the monitoring programme Greenland Ecosystem Monitoring. The spiders were caught in small pitfall traps set up in different vegetation types.

Wolf spiders carry their eggs in a so-called egg sac. The researchers counted the number of eggs in the individual spiders’ egg sacs and compared this information with the time of the season that the animal was caught. By looking at the distribution of the number of eggs in the egg sacs throughout the season, it became clear that in some summers the spiders produced two egg sacs — a phenomenon that is known from warmer latitudes, but which has not previously been observed in the Arctic.

Arctic ecosystems are changing

“We now have the longest time series of spiders collected the Arctic. The large amount of data allows us to show how small animals in the Arctic change their life history in response to climate change,” says Toke T. Høye.

The long time series tells the researchers that the earlier the snow disappears from the ground, the greater the proportion of spiders that can produce a second clutch of offspring.

“These changes in the life history have not been seen earlier and evidence suggests that the phenomenon plays an important role for Arctic insects and spiders,” Toke T. Høye says.

The researchers see the spiders’ response to climate change as an ability to adapt to the new conditions.

Wolf spiders feed on small organisms such as springtails in the soil. If there are more spiders — or insects — in the future Arctic, it can have an influence on the food chains on land.

“We can only speculate about how the ecosystems change, but we can now ascertain that changes in the reproduction of species are an important factor to include when we try to understand how Arctic ecosystems react to the rising temperatures on the planet,” Toke T. Høye says.

Dancing peacock spiders made arachnophobe into arachnologist


One of seven newly described peacock spiders, Maratus azureus, from the southwestern region of the state of Western Australia, was named for the deep blue color on its flashy abdomen. Photo by Joseph Schubert

By John Pickrell, April 15, 2020:

Dancing peacock spiders turned an arachnophobe into an arachnologist

Not yet a college graduate, Joseph Schubert has described 12 of 86 known peacock spider species

Joseph Schubert spends hours at a time lying in the dirt of the Australian outback watching for tiny flickers in the sparse, ground-hugging foliage. The 22-year-old arachnologist is searching for flea-sized peacock spiders, and he admits, he’s a little obsessed.

But it wasn’t always so. Schubert grew up fearing spiders, with parents who were “absolutely terrified” of the eight-legged crawlers. “I was taught that every single spider in the house was going to kill me, and we should squish it and get rid of it,” he says.

Then Schubert stumbled across some photographs of Australia’s endemic peacock spiders, a group named for the adult males’ vivid coloring and flamboyant dance moves aimed at wooing a mate (SN: 9/9/16; SN: 12/8/15). And he was hooked.

“They raise their third pair of legs and dance around and show off like they are the most amazing animals on the planet, which in my eyes they are.” He decided to pursue a career in arachnology. And despite not quite having completed his undergraduate degree in biology, he’s begun working part-time at Museums Victoria in Melbourne, and has already made a mark.

Of the 86 known peacock spider species — each just 2.5 to 6 millimeters in length — 12 have been described by Schubert, including seven named in the March 27 Zootaxa. Those seven were found at a range of sites across Australia, including the barren dunes and shrublands of Victoria state’s Little Desert and the red rocks and arid outback gorges of Kalbarri National Park, north of Perth.

“It’s a fantastic feeling to be able to document these species and empower them with names” that offer scientific recognition as well as a chance for legislated protections if needed, Schubert says. “I am very lucky to work in this field. I get to pull out my microscope and observe things that nobody has ever documented before.”

Sometimes, Schubert finds a peacock spider by looking for draglines of silk glimmering in the sunlight. As these tiny spiders from the genus Maratus leap from leaf to leaf in search of insect prey, they extend these safety lines behind them to catch them in case they fall.

If he’s really lucky, Schubert will catch a male spider mid-boogie, lifting its iridescent abdomen and vigorously waggling its legs in the air as it jerks back and forth in an arachnid tribute to the moonwalk. That usually happens during the Australian springtime in about September and October, as the males become sexually mature towards the end of their lives and take on brightly colored forms.

Those wild colors inspired some interesting names. Schubert’s dubbed one bright blue species with yellow spots Maratus constellatus, because it reminded him of Vincent Van Gogh’s painting The Starry Night. And last year, he called a striking black-and-white jumping spider that is a relative of peacock spiders Jotus karllagerfeldi for the late fashion icon Karl Lagerfeld.

Schubert admits he’s had a lot of help from many Australian photographers, amateur enthusiasts and citizen scientists who send pictures of these miniature spiders to Schubert or share them on social media. Without that vital help, “just a handful of us scientists would be looking … as opposed to thousands [of enthusiasts] uploading via Facebook,” Schubert says.

He still hasn’t entirely gotten over his arachnophobia, though he’s grateful that peacock spiders, while venomous to their tiny insect prey, are harmless to humans. He’s handled hundreds of the spiders and suspects their mouthparts are too small to puncture human skin, even if they wanted to take a bite.

Less charismatic spiders are sometimes still a challenge for Schubert’s nerves, though. In the Little Desert last year, while putting a 5-centimeter-long wolf spider into a container, the spider pushed the lid aside and crawled up Schubert’s arm. “I screamed,” he says, laughing. “But if I can prepare and mentally tell myself that a spider is not looking to hurt me, and even if it does bite me, it’s not going to do anything, then I can put myself in the mental position to handle it.”

The bushfires that swept vast areas of Australia between September and February (SN: 1/13/20) could potentially have burned through the tiny ranges of several peacock spider species found in Victoria’s alpine regions. Nobody has yet been able to check, and future field work is currently on hold amid the ongoing COVID-19 pandemic.

As soon as Schubert can get out again, he will — whether on a research trip or on his next holiday. The only problem, he says, is that “it’s sometimes difficult to find other people who want to spend personal time looking for spiders.”

Cribellate spiders spin thousands of tiny nanofibers into sticky threads. To keep from getting caught in their own webs, these spiders use a nonstick comb on their back legs. Now, researchers reporting in ACS Applied Nano Materials have patterned an antiadhesive nanostructure inspired by this comb onto a foil surface, creating a handy tool to control sticky lab-made nanomaterials for medical, smart textile and other applications: here.

Tarantula spider alternative to addictive opioid medicine


This 2018 video says about itself:

Tarantula Mating: don’t lose your head! | Wild Patagonia | BBC Earth

For tarantulas, finding a mate can be a deadly task – especially when you’ve only got two months left to live.

From the University of Queensland in Australia:

Spider venom key to pain relief without side-effects

April 14, 2020

Molecules in tarantula venom could be used as an alternative to opioid pain killers for people seeking chronic pain relief.

University of Queensland researchers have designed a novel tarantula venom mini-protein that can potentially relieve severe pain without addiction.

Dr Christina Schroeder from UQ’s Institute for Molecular Bioscience said the current opioid crisis around the world meant urgent alternatives to morphine and morphine-like drugs, such as fentanyl and oxycodone, were desperately needed.

“Although opioids are effective in producing pain relief, they come with unwanted side-effects like nausea, constipation and the risk of addiction, placing a huge burden on society,” Dr Schroeder said.

“Our study found that a mini-protein in tarantula venom from the Chinese bird spider, known as Huwentoxin-IV, binds to pain receptors in the body.

“By using a three-pronged approach in our drug design that incorporates the mini-protein, its receptor and the surrounding membrane from the spider venom, we’ve altered this mini-protein resulting in greater potency and specificity for specific pain receptors.

“This ensures that just the right amount of the mini-protein attaches itself to the receptor and the cell membrane surrounding the pain receptors.”

Dr Schroeder said the mini-protein had been tested in mouse models and shown to work effectively.

“Our findings could potentially lead to an alternative method of treating pain without the side-effects and reduce many individuals’ reliance on opioids for pain relief,” she said.

How spiders build webs, time lapse video


This 16 February 2020 video says about itself:

Spider Web Building Time-lapse | BBC Earth

We filmed a garden orb-web spider building their amazing spider web in this time-lapse as well as slow-motion footage as they capture their first prey with it!

Orb-weaver spiders’ colours attract prey


This 3 July 2019 video from Indonesia says about itself:

Kemlanding or giant golden spider or giant golden orbweaver (Nephila pilipes) is a species of web-making spiders, living in forests and gardens, carnivores, rectangular, black and yellow, living in clay, limestone and karst hills at an altitude of about 100-400 meters above sea level.

Females growing up to 5 cm (overall 20 cm) while males only 0.5 cm. Sexual dimorphism of giant golden spider has two main hypotheses, female gigantism and male dwarfism.

N. pilipes builds fine, asymmetrical and elongated nets for up to 2 meters wide at 1-2 meters above the ground. The net is built between pineapple (Ananas comosus), sonokeling (Dalbergia latifolia), teak (Tectona grandis), pine (Pinus merkusii), Earleaf acacia (Acacia auriculiformis) and various shrubs.

From the British Ecological Society:

Orb-weaver spiders’ yellow and black pattern helps them lure prey

February 11, 2020

Summary: Being inconspicuous might seem the best strategy for spiders to catch potential prey in their webs, but many orb-web spiders, which hunt in this way, are brightly colored. New research finds their distinct yellow and black pattern is actually essential in luring prey.

Researchers from Australia, Singapore, Taiwan and the UK placed cardboard cut-out models of the golden orb-weaver, Nephila pilipes, onto real webs in the field. Testing different combinations of colours and patterns they discovered that both the yellow colour and the black and yellow mosaic pattern are essential for luring prey during the day.

The webs of Nephila pilipes also capture prey during the night, and the experiments demonstrated that the yellow colour alone was very effective at luring nocturnal insects.

Orb-weaving spiders are found in different light conditions, and comparisons between many different species revealed a link between light environments and orb-weaver body colour patterns. Species that build their webs in well-lit environments are more likely to evolve the yellow mosaic colour pattern, found to be so effective at luring prey in these experiments.

However, this colour pattern rarely evolves in species that have little opportunity to lure prey, perhaps because they are concealed in a retreat or build their webs in dark caves.

Dr Po Peng, lead author of the study, said, “Our discoveries indicate that the effectiveness of colour-luring to attract prey might be a major driver for the yellow mosaic pattern being present in distantly related orb-weaver spiders.”

The significance of the yellow colour may be due to yellow pollen and flower heads being common in flowers that signal to diurnal (active during the day) pollinators. Previous research has also found that some nocturnal (active at night) Lepidoptera (moths and butterflies) can discriminate colours under dim light conditions and innately prefer yellow.

Orb weaving spiders comprise around 12,500 species, making up 28% of the 45,000 described spider species. The groups defining trait is that they construct webs which they sit in the middle of to forage for prey.

Nephila pilipes were used in these experiments as they are active both diurnally and nocturnally, making them excellent species to study visual prey lures. Flies and bees make up the majority of their diurnal prey; moths and butterflies make up the majority of their nocturnal prey.

The researchers conducted the field experiments at Huayan Mountain in Taiwan between 2008 — 2009. They created five types of cardboard models that looked like Nephila pilipes with their legs outstretched. One accurately mimicked the spiders’ natural colouration. The second had blue spots rather than yellow to test the importance of colour. The third amalgamated the combined area of the yellow into one area to test the importance of the pattern. The fourth and fifth model types were entirely yellow and entirely black.

“To find paper with colour properties most similar to the body parts of N. pilipes, Szu-Wei Chen (co-author) and I did several tours over dozens of stationery stores collecting samples and measuring their reflectance.” Said Po Peng.

In the field experiments, the researchers removed a live spider from its web and randomly selected one of the models to be placed in the centre. They recorded the responses of insects to the cardboard spiders, collecting a combined 1,178 hours of video footage over day and night.

In this study the researchers only looked at the effects of the spiders’ colour and pattern on luring prey and not how they’re perceived by predators. “Previous studies suggest that the area of bright body parts is constrained by diurnally active, visually hunting predators” said Po Peng, “But our results indicated that the yellow mosaic pattern on nocturnal spiders does not represent a trade-off between prey attraction and predator avoidance.” The effect of both colour and pattern on risk from predators or parasitoids is something the researchers feel warrants further investigation.

Why spider webs survive, new research


This 2017 video says about itself:

Beautiful Spider Web Build Time-lapse | BBC Earth

Spiders are the most amazing web architects and using slow motion the Earth Unplugged team captured this Orb spider building a stunning structure.

By Priyanka Runwal in Science News, October 30, 2019 at 6:00 am:

Spider webs don’t rot easily and scientists may have figured out why

Bacteria key to decomposition can’t get at the silk’s nitrogen, a nutrient needed for growth

From spooky abandoned houses to dark forest corners, spider webs have an aura of eternal existence. In reality, the silk threads can last hours to weeks without rotting. That’s because bacteria that would aid decomposition are unable to access the silk’s nitrogen, a nutrient the microbes need for growth and reproduction, a new study suggests.

Previous research had hinted that spider webs might have antimicrobial properties that outright kill bacteria. But subjecting the webs of three spider species to four types of bacteria revealed that the spiders use a resist strategy instead, researchers report October 23 in the Journal of Experimental Biology.

The scientists “challenge something that has gone significantly overlooked”, says Jeffery Yarger, a biochemist at Arizona State University in Tempe, who wasn’t involved in the research. “We just assumed [the silk] has some kind of standard antimicrobial property.”

Spiders spin strings of silk to trap food, wrap their eggs and rappel. Their silk webs can sport leaf debris for camouflage amidst tree canopies or leftover dead insects for a meal later. These bits and bobs lure bacteria and fungi involved in decomposition to the web, exposing the protein-rich web silks to the microbes.

“But [the microbes] don’t seem to affect spider silk,” says Dakota Piorkowski, a biologist at Tunghai University in Taichung, Taiwan.

To check if the silk was lethal to bacteria, Piorkowski’s team placed threads from three tropical spider species — giant golden orb weaver (Nephila pilipes), lawn wolf spider(Hippasa holmerae) and dome tent spider (Cyrtophora moluccensis) — in petri dishes and grew four types of bacteria, including E. coli, in perpendicular lines across the silk. “The idea is that if the silk has antibacterial properties, you should see no growth between the piece of silk and … bacteria,” Piorkowski says.

There was no evidence of this “clear zone” of dead bacteria in spots where the bacteria came in direct contact with the silk, the researchers found. So the team then tested if the silk kept hungry bacteria at bay by blocking them from its nitrogen reserves. Wetting the silk threads with an assortment of nutrient solutions showed that the bacteria readily grew on all three types of spider silk when extra nitrogen was available. That indicated that the bacteria are capable of growing on and possibly decomposing the silk, as long as the threads themselves aren’t the only source of nitrogen.

The researchers hypothesize that an outer coating of fat or complex protein on the silk may block bacteria’s access to nitrogen.

Randy Lewis, a spider silk biologist at Utah State University in Logan, cautions against ruling out antibacterial features in all spider silks, though. Underground webs of tarantulas (SN: 5/23/11), for example, can face environments rife in microorganisms compared with that experienced by aerial web-spinning spiders, he says, and may need the extra protection.