Spiders are not welcome guests in our homes. Some of us jump on the bed, screaming when we see one. Others grab a shoe and smash the spider on sight. Yet others get an empty glass and a piece of stiff paper ready. They trap the spider under the glass, slip the paper under the bottom, and lovingly carry their visitor outside to release it back into nature. Few of us consider the incredible secret life of spiders.
The Best Insecticide
Although it is hard to believe, spiders play a vital role in the world. They are pest control. Spiders avidly devour mosquitoes that can be vectors of disease. They snack on insects that left unchecked could destroy crops. Some species even eat mice. In general, the things that spiders like eating are things that humans don’t want around. The enemies of our enemies are our friends, right?
How much of a difference can spiders make? They’re tiny but have voracious appetites. In 2017, scientists, Martin Nyffeler and Klaus Birkhofer discovered just how much spiders eat. They published their findings in The Science of Nature. By reviewing 65 previous investigations, they estimated that spiders consume between 400 and 800 million tons of insects yearly. Compare that to all the humans in the world who eat 400 million tons of meat and fish in a year. If it weren’t for spiders, there would be a lot more creepy-crawlies around.
Not The Killers we thought They were
Spiders get a bad reputation: poisonous sneaking little beasts that want to kill us all. This is not precisely true. Some spiders have diets that include pollen and fungus spores and their usual living prey (which are insects, not humans, by the way). In 2013, Benjamin Eggs at Exeter University discovered that orb spiders have a diet consisting of 75% delicious bugs and 25% pollen that gets stuck in their webs. These spiders were healthy and seemed to purposely consume the pollen since the particles were big enough so that spiders could have avoided them if they had wanted.
Some spiders risk everything for love, or at least for the chance to mate and procreate. In 2019, George Uetz, with the help of Tricia Rubi and her trained blue jays, studied just how much male wolf spiders will do to win a lovely lady wolf spider’s attention. They published their findings in Behavioural Processes.
When a male wolf spider detects the pheromone trail left by a female, he goes into a frenzy. He waves his very hairy and sexy—at least for the female spiders—legs around like a lunatic. The vibrations created travel to the female spider so that she knows there’s a suitor calling. Female spiders prefer male spiders with the hairiest legs that move them around most frenetically.
Unfortunately, love hurts. The movements that male wolf spiders make to impress females, put them at risk of being eaten by hungry birds, and this study has proven it. Spiders are delicious snacks for our winged friends and important baby food for some species. Chemicals found in spiders promote neurological development in fledglings. When a bird sees a spider, it gobbles it up.
Tricia Rubi trained her blue jays to watch for spiders. When these birds saw one, they pressed a button. Scientists showed the birds videos of unmoving spiders, walking spiders, and spiders doing their sexy dance. Birds most easily detected the spiders looking to impress females, but rarely saw the still spiders.
That is, for baby birds. We mentioned earlier that eating spiders promotes neurological development in baby birds. It can also have an impact on the personality of birds. In 2007, researchers from Glasgow University studied the effect of taurine, a chemical found in spiders.
Taurine, an amino acid, is found in spiders, breast milk, and energy drinks. Scientists observed blue tits that were given a taurine supplement to mimic a diet high in spiders. They also noted differences in blue tits that did not have much taurine as chicks. As adults, the birds which had been fed taurine were bolder and learned more quickly.
A Sticky Situation
It’s a nightmare! There’s a spider on the back of your sleeve. You shake your arm like a mating male wolf spider. Is it off? Is it off yet? No. How do spiders do that? They have real sticking power, and a team of scientists in Germany and Switzerland set out to find out just how sticky they are and how they manage it.
They conducted their research in 2004 and published the results in Smart Materials and Structures. Spiders can stick to almost any surface because their legs are covered in hairs, and those hairs are covered in smaller hairs, called setules. These are what help them stick. When a spider is on a surface, about 600,000 tips of setules are in contact with that surface. The hairs are so small that spiders stick to things molecule to molecule. When they want to move one, they lift their legs in a rolling motion that unsticks one tiny hair at a time. Spiders adhere to surfaces so strongly that up to 170 other spiders would have to hang off of them before causing them to fall when they are on the ceiling.
Spiderwebs may seem like the stuff of nightmares for some. Haunted houses wouldn’t be the same without decorative webs here are there. For others, though, spiderwebs are the stuff of dreams. Spider silk is a very strong material and has qualities that could make it useful in medicine. A comparable weight of spider silk is more durable and flexible than steel. Spider silk does not provoke allergic reactions and, in some cases, can inhibit bacteria and fungi.
We still haven’t exploited spider silk, but in 2017 researchers at the University of Pennsylvania School of Medicine made a significant step forward. They sequenced the genome of the orb spider, which spins 28 different kinds of silk. Additionally, they were able to identify the genes that give spiders the ability to make silk.