Rhinos' feet tested to see how they support heavy loads

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Media caption,

Prof John Hutchinson explains how rhinos at Colchester Zoo have been trained to walk across a hi-tech track

Rhinos are one of the heaviest land animals but one thing puzzles scientists: how do they carry this weight on their stumpy little feet?

Now a team from the Royal Veterinary College (RVC) is trying to find out.

Rhinos at Colchester Zoo have been trained to walk across a hi-tech track that is packed full of sensors.

This will allow the researchers to measure the pressure and forces in the rhinos' feet to reveal how the weight is distributed.

Prof John Hutchinson, from the RVC's structure and motion laboratory, said: "Rhino feet are a bit of a mystery to us.

"There is a little bit known about their anatomy and their health, but nothing that is known about the mechanics of their feet, the physics, the physiology, the detailed anatomy or the behaviour of how they use their feet."

Under pressure

To find out more, the researchers went to Colchester Zoo, where the rhinos have been trained by their keepers.

The animals are given a signal - a gentle touch on the horn with a pole - then the idea is that they walk through a small, narrow enclosure, which has been fitted with the pressure track.

The scientists are looking for the rhinos to step directly onto the middle of each pad as they walk through.

Image caption,
A rhino's foot is surprisingly small given the large amount of weight it has to support

Prof Hutchinson said: "The pressure pads measure the amount of force per unit area that the rhinos are placing on individual regions of their feet at a high resolution."

Dr Olga Panagiotopoulou, who is also working on the study, is interested in looking at the differences between how elephants and rhinos carry their weight.

Elephants have five toes that point forwards, giving them a tip-toed stance, as well as a recently discovered sixth that points towards their heel, and a squishy pad at the back. Rhinos have three rigid toes, with a more evenly spread pad across their feet.

Dr Panagiotopoulou said: "Our preliminary results show that there is a difference in the distribution of weight between an elephant and a rhino's foot.

"Elephants generate the highest pressure on the outside part of the feet, whereas rhinos have the highest pressures on the inside part.

"The next step is to try to see if there are any anatomical differences or differences in the loco-mechanics to account for this."

Heavy load

The team is especially interested in finding out more about rhinos because animals in captivity frequently suffer with problems with their feet. Like cattle, their feet can be trimmed to relieve pressure - but not knowing where the highest pressures are generated makes this a process of trial and error.

Prof Hutchinson said: "The more we know about how their feet work, the more we can help them."

The RVC team also said that learning about how rhinos carry their bulk could also lead to interesting applications in the future.

Prof Hutchinson explained: "From understanding the feet of rhinos, as an example of a big land mammal, we could draw inspiration and understand how to build devices that can handle heavy loads and carry them around while moving."

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