Prehistoric spider journey from Africa to Australia?


This video from Australia says about itself:

2 August 2017

This spider floated 6,000 miles across the Indian Ocean millions of years ago.

By Sarah Zielinski, 9:00am, August 15, 2017:

These spiders crossed an ocean to get to Australia

If you look at a map of the world, it’s easy to think that the vast oceans would be effective barriers to the movement of land animals. And while an elephant can’t swim across the Pacific, it turns out that plenty of plants and animals — and even people — have unintentionally floated across oceans from one continent to another. Now comes evidence that tiny, sedentary trapdoor spiders made such a journey millions of years ago, taking them from Africa all the way across the Indian Ocean to Australia.

Moggridgea rainbowi spiders from Kangaroo Island, off the south coast of Australia, are known as trapdoor spiders because they build a silk-lined burrow in the ground with a secure-fitting lid, notes Sophie Harrison of the University of Adelaide in Australia. The burrow and trapdoor provides the spiders with shelter and protection as well as a means for capturing prey. And it means that the spiders don’t really need to travel farther than a few meters over the course of a lifetime.

There was evidence, though, that the ancestors of these Australian spiders might have traveled millions of meters to get to Australia — from Africa. That isn’t as odd as it might seem, since Australia used to be connected to other continents long ago in the supercontinent Gondwana. And humans have been known to transport species all over the planet. But there’s a third option, too: The spiders might have floated their way across an ocean.

To figure out which story is most likely true, Harrison and her colleagues looked at the spider’s genes. They turned to six genes that have been well-studied by spider biologists seeking to understand relationships between species. The researchers looked at those genes in seven M. rainbowi specimens from Kangaroo Island, five species of Moggridgea spiders from South Africa and seven species of southwestern Australia spiders from the closely related genus Bertmainius.

Using that data, the researchers built a spider family tree that showed which species were most closely related and how long ago their most recent common ancestor lived. M. rainbowi was most closely related to the African Moggridgea spiders, the analysis revealed. And the species split off some 2 million to 16 million years ago, Harrison and her colleagues report August 2 in PLOS ONE.

The timing of the divergence was long after Gondwana split up. And it was long before either the ancestors of Australia’s aboriginal people or later Europeans showed up on the Australian continent. While it may be improbable that a colony of spiders survived a journey of 10,000 kilometers across the Indian Ocean, that is the most likely explanation for how the trapdoor spiders got to Kangaroo Island, the researchers conclude.

Such an ocean journey would not be unprecedented for spiders in this genus, Harrison and her colleagues note. There are three species of Moggridgea spiders that are known to live on islands off the shore of the African continent. Two live on islands that were once part of the mainland, and they may have diverged at the same time that their islands separated from Africa. But the third, M. nesiota, lives on the Comoros, which are volcanic islands. The spiders must have traveled across 340 kilometers of ocean to get there.

These types of spiders may be well-suited to ocean travel. If a large swatch of land washes into the sea, laden with arachnids, the spiders may be able to hide out in their nests for the journey. Plus, they don’t need a lot of food, can resist drowning and even “hold their breath” and survive on stored oxygen during periods of temporary flooding, the researchers note.

Beautiful spider web building time-lapse video


This video says about itself:

Beautiful Spider Web Build Time-lapse – BBC Earth

Using beautiful time-lapse photography the BBC Earth Unplugged team were able to film an Orb spider as it builds a beautifully structured web. If you enjoyed this animal slow motion video then check out our slow motion playlist here.

How spiders mastered spin control. Their silk subtly changes shape as it twists, slowing rotation. By Emily Conover, 7:00am, August 8, 2017.

Ant-mimicking jumping spiders protect themselves


This 2012 video is called Ant mimic jumping spider – Japan Myrmarachne.

From Cornell University in the USA:

Walking like ants gives spiders a chance

July 14, 2017

Summary: To avoid being eaten, some jumping spiders pretend to be ants, a new study has found. Protective mimicry is a remarkable example of adaptive evolution: Moths can be colored like butterflies and grasshoppers may look like tiger beetles. While most mimicry studies focus on traits like color and shape, the researchers in this work used multiple high-speed cameras and behavioral experiments to pinpoint how the spider’s movements mimic ants.

Humans aren’t the only actors on the planet. To avoid being eaten, some jumping spiders pretend to be ants, according to Cornell University research published in Proceedings of the Royal Society B.

Ants are aggressive at defending themselves: They are well-armed with bites, stings and formic acid. Ant-mimicking jumping spiders — Myrmarachne formicaria — in contrast, can’t do much more than run on their eight legs when attacked. Not surprisingly, insect predators tend to prefer spiders over ants, so appearing to be an ant confers significant protection.

Protective mimicry is a remarkable example of adaptive evolution: Moths can be colored like butterflies and grasshoppers may look like tiger beetles. While most mimicry studies focus on traits like color and shape, the researchers used multiple high-speed cameras and behavioral experiments to pinpoint how the spider’s movements mimic ants.

Ant-mimicking spiders walk using all eight legs but pause frequently to raise their forelegs to mimic ant antennae. When walking, they take winding trajectories of about five to 10 body lengths, which made them look like ants following pheromone trails. While the researchers could see what the spiders were doing thanks to high-speed cameras, many potential predators have slower visual systems, so that to them the mimics appear to be moving just like an ant would.

The researchers note that the findings “highlight the importance of dynamic behaviors and observer perception in mimicry.”

Amazing jumping spider video


This video says about itself:

Spider With Three Super Powers – The Hunt – BBC Earth

2 July 2017

Known for eating other spiders, Portia is a genus of the jumping spider that is able to leap up to 50 times her own body length. Captured by stunning close up footage, we get to witness this amazing spider use her super powers to dine on prey three times her size.

World’s strongest spider web


This video says about itself:

Spider Shoots 25 Metre Web – The Hunt – BBC Earth

25 June 2017

Which marvel of nature can build a 2 metre orb web with silk that ranks as the world’s toughest natural fibre? – The answer is the Darwin’s Bark Spider and this real life “Spider Woman” no bigger than a thumbnail has baffled scientists with her web of steel.

These spiders live in Madagascar.

Fishing spider video


This video says about itself:

26 May 2017

If the prospect of a spider that catches fish wasn’t scary enough, the fishing spider is disturbingly well-adapted to its task. This includes walking on water, as well as breathing underneath it as it stalks its prey.

I saw a fishing spider species individual recently in Wooldse Veen nature reserve in the Netherlands.

Walnut orb-weaver spider, European Spider of the Year


This video is called Spider ID: Walnut Orb-Weaver.

The walnut orb-weaver spider has been named European Spider of the Year 2017.

Deutsche Welle radio in Germany writes about it:

Germany’s arachnologists put their focus on this cute creature: Many of us have likely met the walnut orb-weaver spider at some point – around the garden or house. It loves to dwell in old masonry or in the bark of old trees or dead wood. Its cobwebs are large and beautiful: up to 50 inches in diameter.