From making parachutes to building scuba tanks, the arachnids have come up with some fascinating creations
Spider silk is a wonder material that, weight for weight, is stronger than steel, tougher than Kevlar and can be more elastic than rubber. It’s also flexible and antimicrobial. Scientists have used silk to make bulletproof armor, violin strings, medical bandages, optical fiber cables and even extravagant clothing.
“I don’t think people would believe you if you told them, there’s this creature that, if you scaled it up … to the size of the human, it could catch an aeroplane with the material that it makes itself out of itself,” says Fritz Vollrath, an evolutionary biologist at the University of Oxford.
As Cords and Nets to Actively Snare Prey
Silk as a passive web for bugs to fly into may be the least interesting spider hunting method of all. To catch their next meal, spiders may use their silk as nets—or as lassos, whips, binds, disguises, fishing lines and lures.
Most spiders avoid ants because they are often predatory themselves, but one family of spiders treats ants as chow. When the wall spider (Oecobius) gets an ant alone, it runs circles around its victim, all the while churning out a silk cord and wrapping the ant from a safe distance. After the ant is all trundled up, the spider goes in for the kill by chomping the ant at the base of the antennae.
As Parachutes
In 1883, the Krakatoa volcano in present-day Indonesia erupted with the force of over 10,000 hydrogen bombs, obliterating most of the island and converting it into a lifeless wasteland. Three months later, visiting scientists were surprised to find one lifeform present in the region: microscopic spiders.
These spiders weren’t on the newborn island because they survived the blast. Rather, they had travelled there in the aftermath of the eruption—by ballooning. Now a well-known phenomenon, ballooning occurs when spiders stream their silk into the air, catching the winds like a sail for loft. Spiders have been found in the middle of the ocean, hitching a ride on the jet stream and on remote islands hundreds of miles from the mainland. Not all spiders balloon to travel extreme distances—some rely on it to flee from predators or cover short lengths without expending much energy.
As Home Décor
Orb-weaving spiders don’t just construct their homes from silk. Some of these spiders make an effort to decorate it too. They weave throughout their webs stripes of thickly banded silk called stabilimenta. Scientists first though these structures worked to stabilize the web, but the theory was disproved after they found that the patterns were only loosely knitted intro the web’s fabric. Today, the function of stabilimenta is still a mystery.
As Protection from the Elements
Jumping spiders roam freely during the day, but at night or in the midst of cold or rain, they will spin themselves a silken shelter. Jumping spiders use these “pup tents” to shed their external shell safely, store their egg sacs or hibernate. One scientist has speculated that the ability to spin cozy cocoons that insulate the spider from the cold is one reason the Himalayan jumping spider (Euophrys omnisuperstes) can survive the frigid temperatures at elevations of 22,000 feet, making it one of the highest-dwelling, non-migratory animals in the world.
As Buffers Against Tides
One spider spins cocoons to protect itself from the daily tides where it dwells. The Desis spiders scuttle amidst coral, abandoned seashells and the bottoms of kelp on the beach during low tides. When the water rises, the spiders seal themselves in these nooks and crannies with waterproof silk. Researchers have found that the spider lowers its breathing to reduce how fast it burns through the oxygen in its air pocket. Scientists still have questions—such as how the web can withstand salt or how the spider keeps time with the tide.
As Underwater Breathing Tanks
Only one arachnid lives most of its life underwater: the diving bell spider (Argyroneta aquatica). Like all other terrestrial spiders, it only breathes air. Before it submerges, it gloms a bubble onto its posterior as a temporary scuba tank. For a longer-term solution, it spins an air-filled, dome-shaped diving bell with silk on aquatic vegetation as its underwater home.
Diving bell spiders pump up their homes using bubbles they gather from the water surface. Their silken lair permits the exchange of gas molecules to the surrounding water. Scientists have measured oxygen diffusing into the diving bell and carbon dioxide diffusing out to facilitate a spider’s breathing. For this reason, scientists have even likened the homespun structure to a gill. In oxygen-poor waters, these spiders will expand the size of their homes to stuff in more air. Although the gas exchange is efficient, eventually the diving bells shrink, so the spiders need to resurface once a day to gather bubbles for reinflation.
As Door Hinges to Burrows
“Trapdoor spiders and tarantulas will use silks to reinforce the tunnels that they make. So it’s like a building material,” says Sebastian Echeverri, a spider researcher and communicator. Among his 19 pet spiders, his favorites are his two trapdoor spiders.
This kind of spider furnishes its home with a solid door made of soil, leaves and silk. The hinge of the door in particular is spun from silk. These arachnids keep the door shut in the morning and leave it open as they hunt at night, when the spiders are most active. Radiating from the entryway are trails of silk threads that act as trip lines. When a victim touches these threads, the ambush hunters will sense their vibrations through the silk and pounce.
The doors serve as protection, especially against their predatory arch nemesis: parasitic wasps. In the event of an attack, the trapdoor spiders use their fangs to hold the door shut—a move oddly reminiscent of a grumpy human teenager. But the stinging predators usually win out by chewing through the flap. The oldest known spider in the wild, a trapdoor spider residing in southwest Australia, died in 2016 at the age of 43 when it was killed by a parasitic wasp that raided its home.
Leave a Reply