To survive in the desert heat, many animals opt for being active at night or living underneath the scorching sands. But that's not always an option. In an attempt to avoid nocturnal predators, Namib Desert beetles (Onymacris plana) are active during the day, meaning that they must also face temperatures that sometimes soar to 70°C. These sweltering temperatures, coupled with the intense solar radiation in the Namib Desert and their black bodies, mean that these beetles could overheat quickly if they can't cool off. Even though they seek shade frequently, their food is scattered across the dunes, requiring them to scurry across the open sand from one food source to another. With water being so scarce, these insects can't afford to cool themselves by sweating. So how do these black, flightless beetles survive in temperatures that could cook them alive? Carole Roberts, Elizabeth McClain and Duncan Mitchell of the University of the Witwatersrand, South Africa, teamed up with Victoria Goodall of Nelson Mandela University, South Africa, and Mary Seely and Joh Henschel of the Gobabeb Namib Research Institute, Namibia, to see what these insects do to keep themselves from overheating while out in the blazing sun.

The team headed to the Gobabeb Namib Research Institute in the Namib Desert to find these beetles and figure out how they are managing to stay cool enough to survive being out during the hot desert days. Once they had found the beetles, Roberts and colleagues began the difficult task of measuring how hot the muscles inside their thorax get. The researchers held the beetles 15 mm above the sand to stabilise their body temperature. This is the same height that their tiny legs lift their bodies off the sand as they run and can be 20°C cooler than the surface of the sand dunes. Then, the scientists let some of them run off while keeping others stationary. To their surprise, the sprinting beetles cooled down by ∼1.5°C. Also, the body temperature of the stationary beetles rose to 46.5°C – the temperature when beetles seek shade – in only 8 min. This suggests that the beetles can run to cool off, but how is this possible?

‘The cool wind across their bodies created by their sprints might be enough, actually, to cool them down’, explains Mitchell. To find out whether this is how the beetles are cooling off, the scientists headed back into the lab with some beetles in tow to recreate the desert dunes. The team set up heat lamps to resemble the hot desert sun and a fan in front of the beetles to imitate the headwind they make as they run. With no headwind, the temperature inside the tiny insects rose to an astounding 51°C – the highest temperature the beetles can stand. When the fan was turned on, the beetles’ temperature dropped by almost 13°C, keeping them cool even in the blistering heat of the lamps.

So how do the beetles cool themselves by running when any other animal would likely develop heat stroke? Roberts and colleagues believe that it is a combination of the Namib Desert beetle's thin, disc-like shape – which allows it to get rid of excess heat quickly when air is moving over its body – and the fact that they don't use much energy when they're running. Being so energy efficient means that the beetles don't produce much heat while they run and the breeze they create while running is enough to cool themselves down. So, even though these beetles may not seem like they have the ideal attributes to survive in the desert sun, they've managed to beat the heat by developing a strategy all their own: run to keep cool.