Archive for October 28th, 2012

Nature Ramble

Sorry about the last couple of weeks, ran out of steam. In fact, I have been quite out of sorts.

But we’re pretty much back to normal now and should proceed.

This week we travel to Africa, the South African desert actually, and we’re talking about poop.

Dung beetles like to chill on top of balls of poop.

Dung beetles eat feces. Everyone knows this. But here’s something you didn’t know: newly published research reveals that dung beetles can use spheres of rollable poop-meals as portable AC units — and they’re damn effective ones, at that.

The sands of the South African desert can exceed temperatures of 60 degrees Celsius, or 140 degrees Fahrenheit. That’s ridiculously hot. In fact, for a dung beetle like Scarabaeus lamarcki — which transports its meal by rolling it into a ball and pushing it across the scorching desert landscape with its hind legs — it’s too hot, as demonstrated in a study by functional zoologist Jochen Smolka in the latest issue of Current Biology. Using infrared thermography and behavioral experiments, Smolka and his colleagues have shown that dung beetles use their poo-ball as “a mobile thermal refuge” — a portable evaporative unit that cools the beetle slightly as it rolls, and dramatically when it clambers on top of it….

…So what’s the secret to ball-cooling? The big one is evaporation. Dung balls are moist. As that moisture evaporates it keeps the ball very cool — around 32 °C, even when it’s resting atop 60 °C soil. What’s more, note the researchers, “because beetles roll their ball rather than drag it, the ball, preceding the beetle, cools down the sand the beetle is about to step on” by around 1.5 °C.

All told, that means a beetle’s ball of crap helps keep it cool in three ways. First: as a platform, elevated above the scorching desert sand. Second: as a heat sink, drawing heat from the beetle’s forelimbs whenever they start to overheat. And third: as a mobile sand-cooling unit, paving a cooler path for the beetle as it pushes its prize ball of poo from one place to the next.

Source:  io9 There’s more tech stuff and a video clip there.

%d bloggers like this: