Ever wondered how most spider species are found all across the globe when climates are so different and vast waters separate continents?
Biologists at the Natural History Museum in London have just provided the answer. The research was a joint effort of scientists from the University of Nottingham, UK, the University of Granada, Spain, as well as Miyagi University of Education, Japan.
Perhaps fitted for nursery rhymes, the extraordinary characteristics of the spiders that caught the attention of the scientific team include harnessing wind, tossing lines to a safe harbour and weighing anchors to keep safe.
The most common of these features is called ballooning. Spiders use it to catch the breeze in an instantly spread web and use it to fly across vast areas. From one end of the yard to another, or even better, from one continent to another if they mastered their sailing skills.
Ballooning comes as no surprise. The fact that it is used to sail on waters does. Ballooning spiders move at an incredible speed of 30 kilometers per day if the wind is sufficiently strong. Previously, it was thought that ballooning was a land-bound technique. Once the spider would reach water it would undoubtedly perish.
Yet, and this is where the big surprise kicks in, it doesn’t. Spiders have evolved to adapt to any conditions, exhibiting mesmerizing skills.
Dr. Morito Hayashi, lead researcher on the study, stated:
“We have now found that spiders actively adopt postures that allow them to use the wind direction to control their journey on water”.
“They even drop silk and stop on the water surface when they want. This ability compensates for the risks of landing on water after the uncontrolled spider flights”.
In order to reach this conclusions, the team gathered 325 spider specimens ranging across 20 linyphiid species and one tetragnathid species. All of them were placed on trays filled with water to see how they react in the presence of air generated from a pump.
Firstly, the research team observed that all 325 spiders had legs that are water repellent, keeping them rather afloat. With smooth moves, they managed to sail, anchor and walk on water.
The spiders lifted their legs as the air was generated from the pumps to use them as sails. The current smoothly took them across the water trays without one turbulence behind. With some specimens, the scientist observed upsidedown sailing: lifting their abdomen as a sail.
To anchor, the spiders released their silky web on water, which led to the slowing of sailing or full stopping even when strong wind was fueling their sails. To safely harbor, they would spring a thread that would eventually glue to a floating object. Goal achieved, the spider climbs on the silky thread to eventually arrive on the floating object and get out of the water.
At the same time, the specimens were observed to skilfully make use of the wind, by walking on water rapidly in a downwind direction.
The study on the fascinating creatures and their sailing skills is featuring in the BMC Evolutionary Biology journal.
Image Source: The Guardian