Why do dark­ling bee­tles do so well in the Namib Desert?

BBC Wildlife Magazine - - Q&A - Richard Jones

The Namib – a coastal desert that stretches for 2,000km along the south-west coast of Africa – is one of the dri­est habi­tats on Earth. Sur­vival here de­pends on find­ing and re­tain­ing water.

Water loss is a key eco­log­i­cal con­straint for many small in­sects, which rapidly lose vapour through the breath­ing tubes on each body seg­ment, par­tic­u­larly dur­ing flight. Bee­tles, how­ever, equipped with tight-fitting wing­cases, are bet­ter able to com­bat this. In any case, many Namib­ian dark­lings have given up on fly­ing – their wing­cases are fused to­gether, fur­ther im­prov­ing vapour in­su­la­tion.

Dark­lings have also adapted their be­hav­iour to life in the desert. They avoid the heat of the day by scav­eng­ing on dead an­i­mal and plant ma­te­rial after sun­set, and are adept at find­ing mois­ture via a strat­egy known as ‘fog­bask­ing’. Scal­ing the dunes in the early morn­ing, the bee­tles tip their tails into the air to har­ness the mist blow­ing on­shore from the At­lantic, which con­denses on their bod­ies. When a droplet is large enough, it trick­les down water-re­pel­lent grooves to­wards

the mouth.

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