Water spider video


This 7 October 2018 video from Belarus is called Diving bell spider. Water spider. Argyroneta aquatica.

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Ants, spiders and starlings on Twitter


This 2012 video from Britain says about itself:

Murmuration of Starlings in Cornwall in HD – WOW Starling Birds Flocking Together

The most spectacular starling murmuration I have ever seen.

From the British Ecological Society:

Scientists take to Twitter to study flying ants, starling murmurations and house spiders

September 5, 2018

Searching tweets for text or hashtags allowed researchers to gather information on popular ecological phenomena observed in the UK such as the emergence of flying ants and starling murmurations. Their findings are published today in the journal Methods in Ecology and Evolution.

To test how reliable and accurate Twitter is as a data source for scientific research, ecologists from the University of Gloucestershire compared their results directly to three previously published studies on winged ant emergence, autumnal house spider sightings, and starling murmurations. These studies were based on primary data collected by citizen scientists during the same period.

They found that the “Twitter-mined” data was able to replicate most temporal findings, such as date and time of ant mating flights or house spider sightings. The researchers could also reproduce the sex ratio of house spiders by analysing the photos tweeters uploaded and, in some cases, received an indication of where in the house the spider was seen.

Professor Adam Hart from the University of Gloucestershire, who led the study, said: “The retrospective analysis of social media has been used widely to detect earthquakes or political sentiment, but not so much in ecological research. Our study shows that passive citizen science, where we gain information and access to photos indirectly through Twitter or other social media channels such as Facebook and Flickr, can indeed generate robust and interesting data.”

All tweets have an automatic date and time stamp and people generally post on the same day of the actual sighting.

“It is perhaps the immediacy of Twitter, the “urgency” of the phenomena and the desire to connect with other users that have produced so many usable tweets. The emergence of winged ants is also popular in the media and hashtags like #flyingantday often trend on Twitter”, Hart added.

Determining the exact location of a sighting proved more difficult as people rarely indicate it in their posts and it is not necessarily the same as the home location listed in their Twitter bio. Twitter has recently launched the option of having latitude and longitude automatically added to tweets via “share precise location”, which could fill some of these gaps in the future.

As for the observed starling murmurations, 9 of 10 tweets mentioned the geographical location, identifying places such as Blackpool, Aberystwyth, Brighton, the Somerset Levels and East Anglia. These aerial displays often become a hotspot for people wanting to watch them, and thus location is relevant to both tweeter and followers.

Hart concludes: “Twitter can provide a valuable tool for phenological studies of charismatic events and species. Dog owners noting ticks on their animals, or the timing of frog spawning or foxes mating are just some of the questions that could be explored.”

To encourage members of the public to participate in ecological studies, the researchers suggest promoting specific hashtags that make the search through Twitter archives easier. There could also be a system that allows people to automatically record data by tweeting about it.

They stress that Twitter-derived data needs to be interpreted with care though as it can be difficult to validate. Thus, it should be compared directly with data gathered through other more robust methods.

One of the great puzzles of evolutional biology is what induced certain living creatures to abandon solitary existence in favor of living in collaborative societies, as seen in the case of ants and other social, colony-forming insects. A major characteristic of so-called eusocial species is the division of labor between queens that lay eggs and workers that take care of the brood and perform other tasks. But what is it that determines that a queen should lay eggs and that workers shouldn’t reproduce? And how did this distinction come about during the course of evolution? Evolutionary biologists have now found a completely unexpected answer: one single gene called insulin-like peptide 2 (ILP2), which is probably activated by better nutrition, stimulates the ovaries and triggers reproduction: here.

Insects and spiders, David Attenborough video


This video says about itself:

PREDATORS || Micro Monsters With David Attenborough – 2of7 || HD 1080pI.

23 July 2018

The broadcaster continues his bug-eyed view of the world of creepy-crawlies, revealing how predators defuse the defences of their prey. Highlights include the cockroach wasp, busy preparing a tasty – and very live – treat for its young, the whirligig beetle, which employs a water-based radar system, and the jumping Portia spider, which feeds on other arachnids.

Spider-insect relationship, new research


This April 2015 video is about Parasteatoda tepidariorum (American house spider) spiders, objects of recent research.

From eLife:

A common ancestral gene causes body segmentation in spiders and insects

August 21, 2018

Scientists have pinpointed a key gene that controls segmentation during spider development, which reveals a further similarity to the control of segmentation in insects, a study in eLife reports.

The research suggests the Sox gene was duplicated in the spider and then may have replaced the function of another related Sox gene that is still used in segmentation in insects, shedding new light on the evolutionary secrets that allow such a diverse range of animals to build their bodies.

Segmentation is an essential developmental process in arthropods that involves the formation of body segments with different functions. In insects, this happens in two ways — either all segments are made almost simultaneously, or a few segments at the front of the body are specified, such as the head, and then posterior segments are added afterwards, which is similar to what happens in most other arthropods such as spiders.

“We have a detailed and growing understanding of the regulation of segmentation in various insects, but previous studies have shown that some different genetic mechanisms are used to generate segments in spider embryos”, says lead author Christian Paese, PhD Student in the Evolution of Animal Development and Morphology Group at Oxford Brookes University, UK. “In insects, the SoxB gene, Dichaete, is involved in segmentation. Having identified a family of Sox genes in the spider Parasteatoda tepidariorum, we wanted to see whether they also play a role during segmentation in these animals too.”

The team first studied where the different Sox genes are used in spider embryos. They established that Sox21b-1 was supplied by the mother spider, and that its patterns of activity suggested it was involved in segmentation.

To study this further, they used RNA interference to silence the Sox21b-1 gene in the spider and observed the effects on development. This revealed that the gene is needed for segmentation of both the anterior and posterior segments in spiders. In the anterior, Sox21b-1 plays the role of a ‘gap gene’, meaning it is one of the first genes to be switched on in development and specifies the simultaneous formation of some of the leg-bearing segments of the body. In the posterior, Sox21b-1 regulates the ‘segment addition zone’, which allows additional segments to be sequentially added by switching on an important set of developmental genes in the Wnt and Delta-Notch pathways (cell-signalling systems that regulate development in multicellular organisms).

The team also showed that, as well as being involved in segmentation, Sox21b-1 regulates cell division in the early embryo. Although Sox21b-1 silencing had the most pronounced effects on the trunk of the developing spider, causing shortened embryos with missing leg segments, it also influenced the fate of cells in the head region too, which requires further investigation.

“Our work on Sox21b-1 provides important new insights into the evolution and regulation of segmentation in arthropods”, concludes senior author Alistair McGregor, Professor of Evolutionary Developmental Biology at Oxford Brookes University. “It is highly significant that two very closely related SoxB genes are involved in segmentation in both Parasteatoda tepidariorum spiders and in insects, pointing to an ancient role for this subfamily of Sox genes in invertebrates. It will be interesting to examine any segmentation roles of Sox genes in other spiders and arachnids, including those that did not undergo a genome duplication.”

Wolf spiders’ favourite colours


This 2011 video says about itself:

A short video showing some factual aspects of the large Australian Wolf Spider Lycosa sp. behaviour in a typical lawn on the east coast of Australia.

From the University of Cincinnati in the USA:

Do spiders have a favorite color?

Wolf spiders see more than we thought

July 31, 2018

Scientists recently discovered the aptly named peacock jumping spiders have the color vision needed to appreciate the male’s gaudy display.

Now biologists at the University of Cincinnati are studying whether that ability translates to the more humdrum-looking wolf spiders that are muted browns and tans instead of electric blue, fiery orange and stoplight red.

UC biology professor George Uetz and his students presented their work in June at the American Arachnological Society meeting at the University of Michigan.

“The assumption was wolf spiders don’t pay attention to color. But we found that isn’t really true”, Uetz said. “We need to look more closely at the neurobiology of their eyes. We need to understand what their retinas do.”

Like most spiders, wolf spiders have four pairs of eyes, some of which have a reflective lens called a tapetum that sparkles in bright light. If you are an arachnophobe and want a reason never to go in your backyard again, try shining an LED light there some evening and see all the little predators staring back.

Wolf spiders are quickly becoming a model system for study because of labs such as UC’s. Uetz has been examining spider behavior, vision and personality for most of his career. Every study reveals there is more to these creatures than meets their eight eyes.

Most humans have trichromatic vision — they have retinal cells called cones that can see red, green and blue. Wolf spiders, by comparison, have dichromatic vision and see only green and ultraviolet.

“That means they’re basically colorblind. But they’re sensitive to light in the green wavelength”, Uetz said.

In one study presented in June, UC researchers looked at how spiders reacted to a video of courting spiders in which they manipulated the background color, contrast and intensity. Would they react to the courting spider in monochrome? What if the contrast were exaggerated?

Uetz created videos featuring a digital spider and background, both of which could be manipulated to adjust the color and contrast. They played the video for female spiders as well as for male spiders called “eavesdroppers” for their habit of lurking in the background while learning how to mimic other male spiders’ courting displays. They found that female spiders were more likely to respond to videos of males that contrasted sharply from their background. Female spiders also responded better to the color and monochrome than the grayscale version, suggesting color makes a difference to spiders.

“What we found is that for female spiders, intensity matters more than color. But for male eavesdroppers, color matters, too. That is the odd finding. We didn’t expect that at all”, Uetz said.

One surprising finding was that spider eyesight seems to adapt to the changing seasons.

“That makes a lot of sense because when you go out in the early season when the spiders first come out, there are no leaves on the trees so there is broad spectrum light,” Uetz said. “But as the seasons change, leaves come out and everything turns green. Spiders have to be able to see the contrast against a lot of color backgrounds.”

UC’s spider lab keeps about 1,200 wolf spiders (virtually all of them, researchers assure visitors, are accounted for). Students collect juvenile spiders from the same populations of wild spiders living in forests near UC.

In another study, UC postdoctoral researcher Alex Sweger examined the way male wolf spiders use vibrations to woo females. Spiders don’t have ears but can “hear” with tiny sensory organs on their legs that pick up the faint vibrations of prey. Male spiders use a special rasping organ on their pedipalps to produce vibrations that drum the ground, rattling leaves or soil, as part of their ritual mating dance.

Sweger used a laser Doppler vibrometer to measure the spider’s vibrations and reproduce them with a device called a piezoelectric disc bender.

“It’s very similar to the vibrations made by an actual spider. We calibrate the device and attach it to a leaf and see how the female spider responds,” he said.

The ruse works.

Sweger suspected that summer rains are the bane of these spider drummers. He found that males tried to woo females regardless of the weather. But when the ground is wet, they rely more on their visual cues — waving their forelegs in a dance that only female wolf spiders might appreciate.

“They shift to visual behaviors over vibrations on wet leaves, suggesting they are flexible in using different communication modes to suit the conditions”, Sweger said.

Even so, males have far less mating success under wet conditions.

“Their breeding season isn’t very long. Males have a lot of pressure to mate with as many females as possible to increase their genetic success”, Sweger said. “So if you can overcome a hurdle like rain rather than wait for ideal conditions, it benefits you.”

For another study, UC biology student Trinity Walls examined whether juvenile spiders that were classified as shy or bold would maintain that behavior later in life. They did.

To classify her subjects as bold or shy, Walls poked at juvenile spiders with a pair of forceps that simulated a bird’s beak. Shy spiders typically froze in place, relying on camouflage for long periods after the scare, while the bold spiders resumed their foraging or exploration much more quickly. She repeated the scare tactic when the juveniles were older and compared her results.

Intrepid spiders might have more hunting or mating opportunities because of their bold behavior, but they’re also more likely to be seen and eaten. Shy spiders might be fearful but this excess caution means they might be more likely to pass on their genes.

“There are pros and cons to each behavior”, Uetz said. “Bold spiders face more risks from predators drawn to movement. But by moving, they’re more likely to find prey or mates.”

Student Walls came to UC because of the biology department’s spider lab. She has been fascinated by them her entire life, she said.

“I had a pet Mexican red-knee tarantula named Anastasia for eight years,” Walls said. “I love spiders.”

UC student Olivia Bauer-Nilsen examined whether a bacterial infection common to spiders affected the mating behavior of female wolf spiders. Bauer-Nilsen suspected that the immune response from the infection would make the spider too weak or fatigued to mate. Instead, she found the infection had no discernible effect. She presented a poster on the study at the conference.

“It was my first poster. A lot of people say don’t talk to me about spiders ever again. But my family and close friends are not averse to spiders. They’re excited that I’m excited”, she said.

Uetz said even he wasn’t always the fan of spiders he is today.

“I was terrified of spiders before college. Everyone seems to react that way. Spiders are the No. 1 most-feared species on the planet now”, Uetz said. “It’s completely unjustified.”

Uetz said he learned to appreciate spiders in his first biology class when he took a close look.

“When you look at these animals under a microscope, you see them in a completely different way”, he said. “These animals are alien but no less interesting.”