Bondage spider sex

If they did not have to mate with females, male spiders would certainly avoid them altogether. Females are larger, more aggressive, and often eat their suitors before or after sex.

These "bridal veils" have long been suspected to help males avoid becoming a sexual dessert

To take themselves off the menu, male spiders have employed a few tricks that distract, disarm, or detain females.

Some wait until the female's attention is elsewhere – eating a fly, for instance – before trying to copulate. Others use airborne chemicals that act like sexual sedatives, eliciting a state of catalepsy in females.

But male nursery web spiders have a more legs-on approach: they tie the female down with shackles of silk.

These "bridal veils" have long been suspected to help males avoid becoming a sexual dessert. But this idea was not empirically tested until February 2016.

The second insertion allows them to transfer double the amount of sperm

By blocking males' spinnerets using dental silicone, Alissa Anderson and Eileen Hebets of the University of Nebraska-Lincoln demonstrated that sex without bondage nearly always ended with the female eating the male. In contrast, males that could still secrete silk were not eaten.

It is about more than just practising safe sex. Males that tie females up also have a greater chance of becoming fathers, transferring more sperm into the female's two reproductive openings while she is restrained.

"They can only insert one pedipalp [the pair of feelers that are the spider equivalent of a penis] at a time," says Anderson. "And the second insertion allows them to transfer double the amount of sperm."

Bolas spider

When it comes to silk, bolas spiders are the most economical of eight-legged creatures. Their web is just a single strand, stretched from one leaf or twig to another.

Hanging from this zipwire like a trapeze artist, females then craft a sticky yoyo-like weapon, known as a bolas, that they fling at moths that fly too close.

Expecting a sexy tryst, male moths are instead whacked with a wet glob of sticky silk

They do not just build their bolas willy-nilly, however.

"That sticky silk doesn't last very long," says Catherine Scott from the University of Toronto in Canada. "It can dry out. So they don't build it until they know that there's prey within range."

And that does not take long. Bolas spiders are masters of deception, mimicking the sex pheromones of female moths and thereby enticing males to their location with these airborne aphrodisiacs.

Expecting a sexy tryst, male moths are instead whacked with a wet glob of sticky silk. The low viscosity of the bolas penetrates through the moth's outer scales and sticks like super glue.

Like an angler snagging a fish, the spider then reels in its catch of the day. 

Silkhenge

Over 5,000 years after it was built, Stonehenge remains a mystery. Who built it and what purpose did it serve? No one knows for sure.

A similar enigma can be found in nature, deep in the Amazon rainforest.

In 2013, photos of silken structures comprising a vertical pillar surrounded by an intricate fence of white were uploaded to Reddit and Facebook. They went viral, passed around the public and sent to expert entomologists.

What created these "silkhenges"?

"The verdict was that nobody had any idea," says Phil Torres, an entomologist from Los Angeles. "They were just unlike any other structure we'd ever seen."

To solve the case Torres, along with Lary Reeves from the University of Florida, travelled to the Amazon rainforest in 2014, six months after the initial discovery.

After removing a few of the silken structures from branches and leaves and placing them underneath drinking glasses, they soon had an answer. After three days, a tiny spider popped out. Silkhenge is a spider egg sac.

The species remains a mystery, however. "These things were microscopic," says Torres. "It was really difficult to get any sort of ID."

With a DNA sequencer in hand, Torres and Reeves plan to return to the rainforest this summer to correctly classify the spider suspect. They also hope to shed light on what purpose these silken egg sacs serve.

"Our best hypothesis at the moment is that it is to protect the egg from flying parasitoids," says Torres. "[But it could be] something we haven't yet thought of."

The mystery of silkhenge – structures that existed long before their stony namesake – could soon be solved.

Net spider

In a gloomy swamp of the Peruvian rainforest, a net spider is weaving its web, deftly using its legs to craft a fine mesh from the silk that exudes from its spinnerets.

When finished, its masterpiece measures around three inches (7.6cm) across. This is a vast climbing frame for these tiny arachnids, which are only a few millimetres long.

It looks like your typical spider web. Except for one important difference: an additional line of silk that connects the middle of the web to a nearby twig, fastened like an anchor.

This is no static creation. It is a spider slingshot.

By crawling backwards along this dragline, net spiders – colloquially known as slingshot spiders – convert their web into an elastic cone, with themselves at the centre. And there they wait, until they detect a nearby fly on the wing.

"For a long time, people thought that if something is vibrating nearby they would activate the slingshot," says Torres. "But most studies have now indicated that they wait for something to fly into the web."

When this happens, the spider lets go of the coiled up dragline, firing itself – and the web – at high speeds into its prey.

This added momentum increases the amount of contact between the sticky web and any mosquito or midge that triggers the slingshot, reducing the insect's likelihood of escape. "It's a really amazing system," says Torres.

Net-casting spider

Humans have been using nets to catch fish for centuries. But, in the tropical and sub-tropical regions of the world, an ingenious group of spiders – members of the family Deinopidae – has been using them to catch insects for millions of years.

They just wait. Then an insect walks by and then – BOOM! – they'll trigger it

Camouflaged as elongate sticks, the aptly-named net-casting spiders spin an intricate mesh of stretchy, sticky silk between their front four legs.

Held aloft by a harness of strong silk, these ambush predators wait for an unsuspecting insect to crawl or scuttle underneath their trap.

Using two enlarged eyes at the front of their heads and purposely placed trip-wires, these spiders can even detect prey in dim moonlight or darkness.

"They're a visual species," says Torres. "They just wait. Then an insect walks by and then – BOOM! – they'll trigger it," moving their front legs outwards and down, casting the web into a wide net which quickly closes and surrounds the prey below.

It is death from above.

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