A research team from the University of Nottingham in collaboration with the Natural History Museum has found out that some spiders are able to sail over water. The fact that spiders can glide through the air using strands of their web silk was a fact known for a long time. However so far scientists were not able to completely understand how spiders can survive when they travel across whole bodies of water. The paper was published in the journal BMC Evolutionary Biology.
Morito Hayash from the Natural History Museum was the lead author of the study. He remarked:
“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?”
For the study the researchers analyzed 21 common species which live on small islands in the UK. More specifically they gathered 325 adult spiders from nature reserved in Nottinghamshire. The spiders were placed on water trays and the scientists observed the spiders’ behavior when air was generated through a pump. After this they compared this behavior with the one observed on dry surfaces.
According to Hayashi the spiders actively adopted various postures which enabled them to use the wind direction in such a way that they were able to control their movement on water. They even used the web silk as an anchor to stop them or help them slow down their movement on water. This indicates that the silk is used as a way to help the arachnids hang onto objects which are floating on the surface of the water and to reach the shore.
The study is also an important proof of how spiders can adapt when they are exposed to various aquatic environments. This is an important feature because it allows spiders that travel through ballooning to survive in case they fall into the water.
Study co-author Sara Goodacre from the University of Nottingham said that the fact that spiders are able to sail enables them to move from one land mass to another and even across immense spatial scales through air.
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