- By Peter Rissaoui
It would be impossible for a human-sized spider to walk up walls, but what are scientists hoping to learn from this?
A human could not do what Spider-Man can unless 40% of the body was covered in sticky pads and they had impossibly large feet, according to new research. Scientists in Cambridge (UK), Australia and the USA comparing the weight and foot pads of climbing creatures including spiders, found a size limit when it comes to the sticky pads. A gecko is about the largest animal that can climb using this method.
The scientists from the three countries are hoping that the study could help in the development of new adhesive substances.
In order to successfully scale a building the way Marvel comic book hero Spider-Man does, a human would need “impractically large sticky feet, our shoes would need to be a European size 145 or a US size 114” explained Walter Federle, from Cambridge University’s Department of Zoology.
“We’d need about 40% of our total body surface, or roughly 80% of our front, to be covered in sticky footpads if we wanted to do a convincing Spider-Man impression,” Dr David Labonte, from the same department, expanded further.
This means in reality Spider-Man probably could not do what a spider can, but tree frogs, arachnids and geckos can. This is because of the percentage of their body surface covered by adhesive foot pads in relation to their overall weight, the researchers concluded.
The sticky pad percentage increases with body size and weight setting an “evolutionary limit” to the size of animal able to use this climbing method. Anything larger than a gecko would need “impossibly big feet”.
The research teams compared the weight and foot pad size of 225 climbing animal species.
“We were looking at vastly different animals. A spider and a gecko are about as different as a human is to an ant, but if you look at their feet, they have remarkably similar footpads,” Dr Labonte said.
“Adhesive pads of climbing animals are a prime example of convergent evolution, where multiple species have independently, through very different evolutionary histories, arrived at the same solution to a problem. When this happens, it’s a clear sign that it must be a very good solution.”
The research paper’s Co-author Alex Dittrich, a PhD student at Anglia Ruskin University in Cambridge, said: “Different animals have come up with remarkably similar adaptations to dealing with the problem of climbing vertical surfaces, however it appears that there are size limitations on those using sticky foot pads. Spider-Man might need to rethink his methods.”
The researchers hope their work could contribute towards the development of man-made adhesives, which could have important roles to play in engineering, search and rescue and the military.