Spiders can sail over the surface of water using specially-adapted legs as well as web material, a new study concludes. The arachnids do so by using silk as an anchor and their legs as sails, propelling themselves across the water in much the same way as a sailboat.
A total of 325 spiders from 21 species, collected from islands and nature preserves around Nottingham in the United Kingdom, were examined as part of this study. Researchers exposed the animals to blasts of air, comparing the actions of the spiders on solid surfaces to those on water.
This new finding could help explain why spiders are able to migrate across vast distances, quickly colonizing new habitats, researchers state. The spiders were capable of sailing across fresh and salt water in both calm and turbulent conditions.
"For the first time experts in the SpiderLab at The University of Nottingham have described how money spiders use water tension, their legs as a 'rudder' and a good following wind to propel themselves across water," the University of Nottingham reports.
Spiders slow down, or even halt their travel on the water by deploying an anchor of webbing. Researchers believe this material can even be used to attach the animals to floating debris on open water or can be cast to a shoreline to bring the spider back to land.
Many spiders are also capable of a form of flight known as ballooning that can carry the animals up to 19 miles each day. This method of taking to the air involves catching the wind with silk, which provides the impetus to lift the arachnid off the ground. However, the spider has no control over where it travels, and biologists once believed the creature could be in serious danger if it landed on water.
"Even Darwin took note of flying spiders that kept dropping on the Beagle miles away from the sea shore. But given that spiders are terrestrial, and that they do not have control over where they will travel when ballooning, how could evolution allow such risky behavior to be maintained?" Morito Hayashi from the London Natural History Museum said.
Like the 1966 Batman, played by Adam West, these spiders are ready for anything. After striking the surface of the water, they deploy their legs as sails and align their bodies to take full advantage of the wind.
Sailing behavior could even help some spiders incapable of ballooning, when heavy rains or other conditions produce local flooding, researchers concluded.
Study of the sailing capabilities of spiders was profiled in the journal BMC Evolutionary Biology.
