So it has come to my attention that, get this, spiders can now conquer the waves by, thats right, Sailing!
It is a whole other level of arachnophobia right there. Until about a week ago the dispersal of spiders would mainly have to be by ‘ballooning’ a strategy that Charles Darwin coined upon the Beagle in 1832, after seeing thousands of tiny red spiders ‘floating’ aboard the ship using parachutes made of silk. These observations lead to the conclusions that the ‘ballooning’ behaviour was well established within these species. Darwin would also be surprised to find that ballooning spiders are also competent sailors on water too.
A paper published in BMC Evolutionary Biology shows that these sailing behaviour for the first time. Being able to move over water is a highly needed for species were aerial dispersal is relied on so heavily, just in case of a water landing.
Now sailing in spiders unfortunately doesn’t involved miniature boats and life vests, instead the ‘sailing’ behaviours are 5 different water-related behaviours that the spiders, more than 20 different species, displayed upon being placed in a shallow tray with 1cm water depth, then having air pump-generated ( to mimic wind).
The five behaviours consist of sailing, upside down sailing, anchoring, walking and death mimicry. The sailing behaviour, and the upside down sailing, is the raising of the legs, or abdomen, to allow to ‘catch’ wind, much like actual sails. Anchoring is the release of silk onto the surface of the water; this in turn slows the spider’s movement and may help to tether the spider to floating objects. Walking is the spider rapidly moving its legs in an attempt to walk across the water’s surface. Death mimicry is in fact a lack of sailing behaviour but due to the spider’s size and its water-repellent feet is simply floats until reaching dry land.
It was found that the species and individuals that showed a preference and keenness to balloon their way off of dry surfaces were also found to be the most adapt at the talent for sailing. The scientists have concluded “the sailing behaviour is almost completely associated with, and possible a requirement for, the aeronautic behaviour.”
The paper;
Morito Hayashi, Mohammed Bakkali, Alexander Hyde & Sara L. Goodacre (2015) Sail or sink: novel behavioural adaptations on water in aerially dispersing species. BMC Evolutionary Biology 2015
