A sea of floating, dead tarantula skins might be an arachnophobe鈥檚 nightmare, but the moults of these spiders could help mop up ocean oil spills.
Spider skins have 鈥渧ery strong鈥� water-repelling properties, says Tomasz Macha艂owski at Pozna艅 University of Technology in Poland, one of the team behind the concept. This means they could be useful for cleaning-up oil spills, as the materials used need to attract oil but also repel water to stop them from sinking.
Oil clean-up operations often use synthetic materials that are similar to plastic, but these cause ocean pollution and can be toxic to marine life. Organic materials such as wool, feathers and human hair are used as natural alternatives. But some of these can be ineffective at soaking up oil on the ocean鈥檚 surface because they can also trap water, causing them to sink.
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Tarantula skins
Spider skin is mainly made of chitin, a biopolymer that is also found in the tough exoskeletons of crustaceans. Chitin is widely used to clean up oil spills as its molecular structure soaks up the oil. So Macha艂owski and his colleagues wanted to find out if the skin shed by Peru purple tarantulas (Avicularia sp.), a species of spider that sheds a large number of skins during its life cycle, could be an efficient oil sponge.
They put 100 milligrams of shed tarantula skin in a dish with 60 millilitres of seawater that had 2 grams of crude oil on the surface, then measured how much oil was soaked up.
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After 2 minutes, the tarantula skin had captured 63 per cent of the oil 鈥� nearly 13 times its own weight 鈥� while absorbing very little water.
Macha艂owski says the dense, bristly hairs trap the oil, while the irregular arrangement of the hair helps it to clump together and lock the oil in. The oil is soaked up via a similar mechanism to capillary action.
Machalowski and his colleagues say there are 190,000 spider breeders worldwide. Based on this, they estimate that almost 5 million shed skins could be harvested every year via breeders to clean up ocean oil spills and decontaminate industrial waste water. Theoretically, the skins could be cleaned and reused, although this reduces their ability to soak up oil, the team also showed.
鈥淭his is a very unusual concept, but surprisingly effective,鈥� says Megan Murray at the University of Technology Sydney. 鈥淚鈥檓 not sure how this can scale up for a real-world solution, but the physical mechanism could inspire new material designs.鈥�
Journal of Environmental Management
