It’s always the big guns that grab the headlines.
Yesterday, we watched two leopards do battle, which was a lifesaver for the third party involved, a warthog.
Today, we turn our attention to one of the unheralded heroes of the southern African natural landscape, the humble dung beetle.
It’s tough getting the plaudits when you’re most renowned for rolling around balls of turd, but let’s not underestimate the sophisticated skills in action.
National Geographic is impressed, and so are we:
Using scent detectors on their antennae, dung beetles home in on a pile of feces and descend en masse. Each beetle then races to tear off a chunk, roll it away, bury it, and devour the droppings before the other dung beetles can steal it for their own. But how they are able to navigate away from the fray, and do so in efficient, straight lines, has been the topic of intense study.
Massive respect to those who devote themselves to such studies, by the way. I would imagine it could make for some awkward glances over Christmas lunch with the extended family, but science needs you.
They actually use many different methods to navigate:
In 2003, a scientist by the name of Marie Dacke discovered that nocturnal dung beetle species like Scarabaeus zambesianus can navigate by the polarized light of the moon. A decade later, Dacke found that another species, Scarabaeus satyrus, uses the light of the Milky Way when the moon isn’t available. A year after that she revealed that day-rolling species such as Scarabaeus lamarcki look to the sun as their guiding star.
All of that is amazing, and puts that one friend of yours who tries to get into people’s pants by pointing out the constellations to shame.
Dacke’s studies weren’t done, and she has now uncovered another tool:
According to a study published today in the Proceedings of the National Academy of Sciences, when the sun is at its highest point in the sky and thus useless for navigation, dung beetles abandon the ball of fire and decide to follow the wind instead.
The findings suggest that the animals can interpret two different kinds of signals and opt to use one or the other depending on the conditions around them.
“These systems appear to be extremely flexible,” Dacke says. “Which is fascinating when you imagine that their brain is about the size of a sesame seed.”
I feel an immense sense of achievement every time I arrive somewhere having used Google Maps, and these beetles are shaming us.
Figuring out the wind navigation system was no small feat, with Dacke and her team required to remove a number of variables. Having done so, the full skillset of the beetles became apparent:
“They will follow the wind, because that is now the cue that they are using,” says Dacke, who is an expert in neuroethology, or the study of how the nervous system controls behavior. “If we change the direction of the wind by 180 degrees, the beetle will change its direction by 180 degrees as well.”
But things really got interesting when the team prevented the beetles from accessing some of their sensory systems.
In one experiment, the scientists removed the club at the end of the insect’s antennae, which is thought to help them sense odors.
Like the others, these beetles successfully followed the wind when the sun was high. This suggested that the beetles were feeling the wind rather than smelling something in it.
That excellent photo above was taken by Chris Collingridge.
The final step was to remove the antennae altogether, which resulted in the rudderless beetles rolling their balls without direction.
If you’re looking for a word to sum up what this all means, it’s the fabled “cognition”:
What’s more, it’s important that dung beetles seem to be merging two different kinds of information—one mechanical, the other visual—into a single brain region. [Paul Graham, who studies ant navigation at the University of Sussex] says this suggests “even small-brained animals are undertaking sensory processing that is reminiscent of what some people would call cognition.”
Researchers aren’t yet done, and the next step involves a deep dive into how the beetles decide which information to utilise at any given time. This will involve recording the beetles’ neurons.
Sheesh, talk about newfound respect for both beetle and researcher.
I’ve said it before and I’ll say it again – nature, what a rush!
[source:natgeo]
