Spider attacks its reflection, video


This video shows a Marpissa muscosa spider attacking its reflection in a faucet in a bathroom in the Netherlands, thinking the reflection is a rival.

Dutch arachnologist Peter van Helsdingen knew this kind of behaviour from birds, but had never seen it in spiders before.

Ben Langeveld made the video.

Advertisements

New Sri Lankan spiders get Enid Blyton names


This video says about itself:

Science Bulletins: Seeking Spiders—Biodiversity on a Different Scale

4 October 2012

Recognizing the tiny species of any ecosystem is hugely important for defining its overall diversity. But miniscule forms of life are often invisible to conservation efforts because they have yet to be described in detail. Dr. Norman Platnick of the American Museum of Natural History is leading an important initiative to discover biodiversity on a smaller scale. Having devoted decades to the study of spiders, Dr. Platnick now leads a team of 45 investigators from 10 countries in the largest-ever research project on spiders, identifying members of the goblin spider family. This group of spiders is widely distributed but largely unknown, primarily due to their small size—at 1.2-3mm, they measure one-half to one-third the length of the average spider. This video follows Dr. Platnick’s team into the Ecuadorian jungle as they collect and identify scores of unrecognized goblin spiders, showing how little we know about the full breadth of global biodiversity.

From ScienceDaily:

Six new species of goblin spiders named after famous goblins and brownies

June 21, 2018

Summary: A remarkably high diversity of goblin spiders is reported from the Sri Lankan forests. Nine new species are described in a recent paper, where six are named after goblins and brownies from Enid Blyton‘s children’s books. There are now 45 goblin spider species belonging to 13 genera known to inhabit the island country.

Fictional characters originally ‘described’ by famous English children’s writer Enid Blyton have given their names to six new species of minute goblin spiders discovered in the diminishing forests of Sri Lanka.

The goblins Bom, Snooky and Tumpy and the brownies Chippy, Snippy and Tiggy made their way from the pages of: “The Goblins Looking-Glass” (1947), “Billy’s Little Boats” (1971) and “The Firework Goblins” (1971) to the scientific literature in a quest to shed light on the remarkable biodiversity of the island country of Sri Lanka, Indian Ocean.

As a result of their own adventure, which included sifting through the leaf litter of the local forests, scientists Prof. Suresh P. Benjamin and Ms. Sasanka Ranasinghe of the National Institute of Fundamental Studies, Sri Lanka, described a total of nine goblin spider species in six genera as new to science. Two of these genera are reported for the very first time from outside Australia.

Their paper is published in the open access journal Evolutionary Systematics.

With a total of 45 species in 13 genera, the goblin spider fauna in Sri Lanka — a country taking up merely 65,610 km2 — is already remarkably abundant. Moreover, apart from their diversity, these spiders amaze with their extreme endemism. While some of the six-eyed goblins can only be found at a few sites, other species can be seen nowhere outside a single forest patch.

“Being short-range endemics with very restricted distributions, these species may prove to be very important when it comes to monitoring the effects of climate change and other threats for the forest habitats in Sri Lanka”, explain the researchers.

In European folklore, goblins and brownies are known as closely related small and often mischievous fairy-like creatures, which live in human homes and even do chores while the family is asleep, since they avoid being seen. In exchange, they expect from their ‘hosts’ to leave food for them.

Similarly, at size of a few millimetres, goblin spiders are extremely tough to notice on the forest floors they call home. Further, taking into consideration the anthropogenic factors affecting their habitat, the arachnids also turn out to be heavily dependent on humans.

How spiders fly


This 1977 music video is called Flyin’ Spiderz – City Boy.

The Flyin’ Spiderz were a Dutch punk rock band.

However, there are also real flying spiders.

This 2015 video says about itself:

Flying Spiders: See Them in Action | National Geographic

Some say that flying is just falling with style. But for the Selenops spider it’s an important defense mechanism. Researchers recently discovered that this arachnid is able to flip itself over and steer quickly back to the safety of its home base when it needs to elude an approaching predator.

From PLOS:

Flying spiders sense meteorological conditions, use nanoscale fibers to float on the wind

The crab spider spins out tens of fine silk fibers for its aerial dispersal

June 14, 2018

Spiders take flight on the smallest of breezes by first sensing the wind, and then spinning out dozens of nanoscale fibers up to seven meters long, according to a study publishing June 14 in the open-access journal PLOS Biology by Moonsung Cho, Ingo Rechenberg, Peter Neubauer, and Christoph Fahrenson at the Technische Universität in Berlin. The study provides an unprecedentedly detailed look at the “ballooning” behavior that allows certain spiders to travel on the wind for hundreds of kilometers.

Many kinds of spiders engage in ballooning, either to disperse from their birth site, to search for food or mates, or to find new sites for colonization. While most ballooning spiders are juveniles or small adults, under 3 millimeters in length, some larger adults also balloon. Although the behavior has been studied before, these authors are the first to make detailed measurements of both the sensing behavior and the silk fibers that are used to catch the wind.

Through a combination of field observations and wind tunnel experiments, they found that large crab spiders (Xysticus species), about 5 mm long and weighing up to 25 milligrams, actively evaluated wind conditions by repeatedly raising one or both front legs and orienting to the wind direction. At wind speeds under 3.0 m/sec (7 mph), with relatively light updrafts, the spiders spun out multiple ballooning silks averaging 3 meters long, before releasing themselves from a separate silk line anchoring them to the blade of grass from which they launched. A single spider released up to 60 fibers, most of them as thin as 200 nanometers. These fibers differed from a drag line, which has been known as a ballooning line, and were produced by a separate silk gland.

This video says about itself:

3 April 2018

An Observational Study of Ballooning in Large Spiders: Nanoscale Multi-Fibres Enable Large Spiders’ Soaring Flight

The PLOS article continues:

The authors concluded that ballooning spiders actively sense wind characteristics and launch only when the wind speed and updraft are within relatively narrow ranges, increasing the odds of a productive flight. According to the fluid dynamic calculations the authors performed using their wind tunnel data, the spider relies on updrafts that form in the light winds into which they launch, further ensuring a successful flight.

“The pre-flight behaviors we observed suggest that crab spiders are evaluating meteorological conditions before their takeoff,” Cho said. “Ballooning is likely not just a random launch into the wind, but one that occurs when conditions most favor a productive journey.”

The aerodynamic capabilities of spiders have intrigued scientists for hundreds of years. Scientists have attributed the flying behavior of these wingless arthropods to ‘ballooning’, where spiders can be carried thousands of miles by releasing trails of silk that propel them up and out on the wind. However, the fact that ballooning has been observed when there is no wind to speak of, when skies are overcast and even in rainy conditions, raises the question: how do spiders take off with low levels of aerodynamic drag? Here.

Dinosaur age tick in spider web preserved in amber


This 2014 video is called Spider webbing up a tick.

And now, all the way back from 2014 to the age of dinosaurs

From the University of Kansas in the USA:

For 100 million years, amber freezes a tableau of tick‘s worst day ever

June 13, 2018

Summary: This is the first time this kind of interaction between ticks and spiders has been documented in the fossil record. Even though ticks aren’t a typical staple of spider diets, spiders can occasionally prey on ticks in modern ecosystems.

One day in Myanmar during the Cretaceous period, a tick managed to ensnare itself in a spider web. Realizing its predicament, the tick struggled to get free. But the spider that built the web was having none of it. The spider popped over to the doomed tick and quickly wrapped it up in silk, immobilizing it for eternity.

We know the outline of this primordial worst-day-ever because the silk-wrapped tick subsequently was entombed in amber that may have dripped from a nearby tree. Its fate, literally, was sealed.

Fast-forward 100 million years or so, and that same tick was discovered by a German collector named Patrick Müller who was searching in Myanmar for Burmese amber pieces of scientific value. He passed the discovery on to scientist Jason Dunlop at the Museum für Naturkunde in Berlin, who realized it was an important specimen.

“Dunlop brought in Lidia Chitimia-Dobler, who is a tick expert at the Bundeswehr Institute of Microbiology, and myself because we’ve worked together on Burmese amber things,” said Paul Selden, distinguished professor of geology at the University of Kansas and director of the Paleontological Institute at the KU Biodiversity Institute and Natural History Museum.

Together with microscopy expert Timo Pfeffer, the team has just published a description of the tick in the journal Cretaceous Research.

“It’s a show of behavior, really,” said Selden. “Ticks already are known from the Burmese amber — but it’s unusual to find one wrapped in spider silk. We’re not sure if the spider wrapped it in order to eat it later or if it was to get it out of the way and stop it from wriggling and destroying its web. That’s something spiders do.”

Selden said ticks are seldom found in Burmese amber, though the few that have been discovered were proved to be among the oldest tick specimens known to science.

“They’re rare because ticks don’t crawl around on tree trunks,” he said. “Amber is tree resin, so it tends to capture things that crawl around on bark or the base of the tree. But ticks tend to be on long grass or bushes, waiting for passing animals to brush up against them, though some of them can be on birds or squirrels, or maybe a little crawling dinosaur.”

The researchers took pains to ensure the ancient tick was indeed bound in spider silk, rather than fungal filaments that sometimes can grow around a dead tick.

“We think this was spider silk because of the angles that the threads make,” Selden said. “Also, in the paper, we show a picture of a tick that started to decay — and the fungus on that tick grows from its orifices — from the inside to the outside. Whereas these threads are wrapped around externally and not concentrated at the orifices.”

According to the research team, this is the first time this kind of interaction between ticks and spiders has been documented in the fossil record. Even though ticks aren’t a typical staple of spider diets, spiders can occasionally prey on ticks in modern ecosystems.

“Just last year, I was on a field trip in Estonia and took a photo of a Steatoda spider wrapping up a red spider mite“, said Selden. “That was serendipitous.”

The KU researcher and his colleagues are unable to determine the species of spider that wrapped the tick because families of spiders known to catch ticks today lack a convincing Mesozoic fossil record. While it’s difficult to identify the producer of the fossil silk with any certainty, it’s safe to assume the spider’s behavior was characteristic of most known spiders in the forest today.

“We don’t know what kind of spider this was”, Selden said. “A spider’s web is stretched between twigs to catch prey that flies or bumps or crawls into it. As prey gets stuck, it adheres to the web and starts to struggle. Maybe some things can escape after some struggle, so the spider rushes to it out from hiding and wraps it in swaths of silk to immobilize it, to stop it escaping or destroying the web. This prevents prey from hitting back — stinging or biting — once it’s wrapped in silk it can’t move, and then the spider can bite it and inject gastric fluid to eat it or venom to subdue it as well.”

The amber that preserved the small drama occurring between the spider and tick from 100 million years ago offers a thought-provoking peek into the natural past, according to Selden.

“It’s really just an interesting little story — a piece of frozen behavior and an interaction between two organisms,” he said. “Rather than being the oldest thing or the biggest thing, it’s nice to be able to preserve some animal interaction and show it was a living ecosystem.”

Rabbit hutch spider, European Spider of the Year 2018


This video says about itself:

Steatoda bipunctata – the Common false-widow

18 June 2014

Steatoda bipunctata is a very common spider, both in nature and inside and around houses. Notice its pink eggs and spiderlings. The spider doesn’t mind taking prey larger than itself.

More info on this spider here.

The European Society of Arachnology has voted this species, also called rabbit hutch spider, European Spider of the Year 2018.

Madagascar colourful little spiders, new research


This 2014 video about a Phoroncidia americana spider says about itself:

Very tiny cob web spider rarely seen. It is on the tip end of a fern leaf.

From Harvard University in the USA:

Tiny spiders, big color

Study reveals how tiny Madagascar spiders retain their color over decades

May 11, 2018

There’s plenty that’s striking about Phoroncidia rubroargentea, a species of spider native to Madagascar, starting with their size — at just three millimeters, they’re barely larger than a few grains of salt.

But the reason they caught Sarah Kariko’s eye had more to do with their color.

Unlike many other species, which gradually see their color leach away when preserved in ethanol, the tiny spiders dazzled with brilliant, shimmering red and silver, even after decades in ethanol.

Phoroncidia rubroargentea colours

“I was sorting through specimens from my expeditions to Madagascar and these little red spiders kept catching my eye,” Kariko said. “I asked a colleague, ‘Have you ever seen this before?’ When I started going through the same spider species on the shelves in the collection and then began examining specimens from other museums they looked like this too, so I started asking how is this happening? What is going on here?”

Those questions were the start of a journey that would lead Kariko and several other Harvard scientists (plus two scientists from the Weizmann Institute of Science) to investigate both how the tiny spiders produce their distinctive colors and why they are so surprisingly durable.

Their findings, published in 2018 as a cover article in the Journal of the Royal Society Interface, show that the spiders actually use a combination of strategies — including structural colors and pigment and fluorescent material — to produce their colors, and that all of it is protected by a tough cuticle layer.

“We don’t yet know exactly why these spiders have this coloration,” Kariko said. “There are many visual predators, like chameleons, in the forests where these spiders are found, so it’s possible this may be a warning or protective coloring. With this paper, we’ve made some inroads into how they make these colors, but the why is still a mystery we hope to eventually unravel.”

The first step in dismantling the spider’s colors involved James Weaver from Harvard’s Wyss Institute for Biologically Inspired Engineering who examined the specimens with Kariko, and then contacted Mathias Kolle while he was with Joanna Aizenberg‘s Biomineralization and Biomimetics Lab (he is now a professor in MIT’s Department of Mechanical Engineering) to perform spectroscopy measurements.

They quickly realized they also needed someone with a special skillset in material science as well as excellent manual dexterity to work with these tiny specimens, so they contacted Ling Li.

Li, a postdoctoral fellow at the Wyss Institute (and now a professor in Virginia Tech’s Department of Mechanical Engineering), used a broad array of imaging techniques — from optical microscopy to fluorescence to electron microscopy — to examine the colors in precise detail.

The team expanded to include Jaakko Timonen from the John A. Paulson School of Engineering and Applied Sciences (and now a professor at Aalto University in Finland), who conducted detailed fluorescence imaging of the spider specimens, as well as Carolyn Marks, biological imaging scientist at the Center for Nanoscale Systems, who was also brought on board to help prepare and examine very thin slices of the spider.

Very quickly, said Li and Kolle, it became clear that the silver color was the result of a material similar to that found in reflective fish scales.

That structure functions, Kolle said, by stacking a series of tiny, 100-nanometer thick plates — about 1/1000th the width of a human hair — made of highly reflective material on top of each other. Each plate reflects light at a slightly different wavelength and those wavelengths either cancel each other out or add up to produce color.

“Ling’s analysis brought this out beautifully,” Kolle said. “We were able to image these platelets and show that they have a specific thickness, but there is no specific control of the spacing between them. That means some areas might filter out red and reflect it strongly, and other areas might do the same for blue, or for green. When you add all that up, you get the silver color.”

“We were able to show that this silver color is structural,” Li added. “So that explains why the color doesn’t fade away — it’s built into the structure.”

The team also found that the (non-structural) red color is able to resist fading in ethanol because the pigment is trapped in an array of tiny “microspheres” that are only about one micron in diameter.

“To the best of our knowledge this is something unique, I think, in terms of spiders,” Li said. “We don’t yet know the exact chemical components of the pigment, but it appears these microspheres contribute to the stability of the red color.”

The spider’s color protections, however, don’t end there.

“It is likely the colors’ stability is also enhanced by an outer cuticle layer,” Li said. “This is a hard-bodied spider, so that cuticle surface is relatively thick and hard, and robust, which could provide additional mechanical and chemical stability. Around the silver color, the cuticle is very uniform and transparent, but in the red area, it is modified to include additional pigment which adds to the red color.” And while this color is surprisingly stable over time, their experiments also show that its long term resistivity to chemical attack by the surrounding fixatives is also sensitive to mechanical disruption or other impacts, which can damage the complex multi-component pigment based system.

The team’s analysis of how the spiders produce their distinctive color also uncovered evidence of an unusual phenomenon, called “twinning” in the structure of the plates used to produce the silver color. Two scientists from the Weizmann Institute, Leslie Leiserowitz and Dvir Gur, brought their expertise in crystallography to help the team identify the characteristics of atomic arrangement of these guanine crystals by using the structural data acquired by Li and Kariko.

“These plates are made of guanine crystals — the same material found in reflective fish scales — but in this case, the plates are not a single crystal, there is a twinning plane that runs parallel to the orientation of the crystal. Essentially, there are two crystals facing each other so the atoms are arranged in mirror symmetry.”

Though such structures have been observed in two other animals — copepod bodies and scallop eyes — P. rubroargentea is the first known example of twining in arachnids, Kariko said.

Though the team is still working to understand exactly why twinning occurs, Li suggested it may be necessary to ensure the platelets grow to the proper thickness to achieve their desired optical properties.

Ultimately, Kolle said, the hope is that a better understanding of how the spiders produce their vivid and long-lasting color might also yield valuable insights that could be applied to other questions in materials science.

“The take home message here is if you are building a new material for a given purpose and you have certain criteria you want to satisfy, like color robustness,” Kolle said. “We can take some of these natural solutions as a starting point.”

Phoroncidia rubroargentea is also the spider that inspired Kariko to create the Spider Super Hero Program, designed initially for pediatric oncology and hematology patients at the Floating Hospital for Children, and later expanded for Harvard’s Museum of Natural History — it has now reached more than 200 children and their families.

In this program, participants take part in an imaginary expedition around the world to meet many different spider species and learn about their adaptations (or “super powers”), that contribute to their survival in their specific habitats.

After this initial introduction to spider biodiversity, the children would then design their very own spider super hero to help them with a real world challenge that they are facing and could use a little extra help with. In the case of P. rubroargentea, for example, this spider could remind us that even if you are going through chemotherapy or something else — she can help us remember how beautiful we can stay inside and out regardless of the difficulties we encounter along the way.

“There are many ways to be inspired by the natural world,” Kariko said. “The hope is this program can help open our eyes to the beauty and possibility from even the littlest creatures among us.”

In order to strengthen the efficacy of vaccines on the immune system — and in particular on T lymphocytes, specialized in the detection of cancer cells — researchers have developed spider silk microcapsules capable of delivering the vaccine directly to the heart of immune cells: here.