Close-up film shows for the first time how ants use ‘combs’ and ‘brushes’ to keep their antennae clean

jeh98 — Mon, 27 Jul 2015 15:53:30 +0000

For an insect, grooming is a serious business. If the incredibly sensitive hairs on their antennae get too dirty, they are unable to smell food, follow pheromone trails or communicate. So insects spend a significant proportion of their time just keeping themselves clean. Until now, however, no-one has really investigated the mechanics of how they actually go about this.

In a study published in Open Science, Alexander Hackmann and colleagues from the Department of Zoology have undertaken the first biomechanical investigation of how ants use different types of hairs in their cleaning apparatus to clear away dirt from their antennae.

“Insects have developed ingenious ways of cleaning very small, sensitive structures, so finding out exactly how they work could have fascinating applications for nanotechnology – where contamination of small things, especially electronic devices, is a big problem. Different insects have all kinds of different cleaning devices, but no-one has really looked at their mechanical function in detail before,” explains Hackmann.

Camponotus rufifemur ants possess a specialised cleaning structure on their front legs that is actively used to groom their antennae. A notch and spur covered in different types of hairs form a cleaning device similar in shape to a tiny lobster claw. During a cleaning movement, the antenna is pulled through the device which clears away dirt particles using ‘bristles’, a ‘comb’ and a ‘brush’.

To investigate how the different hairs work, Hackmann painstakingly constructed an experimental mechanism to mimic the ant’s movements and pull antennae through the cleaning structure under a powerful microscope. This allowed him to film the process in extreme close up and to measure the cleaning efficiency of the hairs using fluorescent particles.

What he discovered was that the three clusters of hairs perform a different function in the cleaning process. ̽��ֱ��dirty antenna surface first comes into contact with the ‘bristles’ (shown in the image in red) which scratch away the largest particles. It is then drawn past the ‘comb’ (shown in the image in blue) which removes smaller particles that get trapped between the comb hairs. Finally, it is drawn through the ‘brush’ (shown in the image in green) which removes the smallest particles.

“While the ‘bristles’ and the ‘comb’ scrape off larger particles mechanically, the ‘brush’ seems to attract smaller dirt particles from the antenna by adhesion,” says Hackmann, who works in the laboratory of Dr Walter Federle.

Where the ‘bristles’ and ‘comb’ are rounded and fairly rigid, the ‘brush’ hairs are flat, bendy and covered in ridges – this increases the surface area for contact with the dirt particles, which stick to the hairs. Researchers do not yet know what makes the ‘brush’ hairs sticky – whether it is due to electrostatic forces, sticky secretions, or a combination of factors.

“ ̽��ֱ��arrangement of ‘bristles’, ‘combs’ and ‘brush’ lets the cleaning structure work as a particle filter that can clean different sized dirt particles with a single cleaning stroke,” says Hackmann. “Modern nanofabrication techniques face similar problems with surface contamination, and as a result the fabrication of micron-scale devices requires very expensive cleanroom technology. We hope that understanding the biological system will lead to building bioinspired devices for cleaning on micro and nano scales.”

Dr Federle’s laboratory and, in part, this project receive financial support from the Biotechnology and Biological Sciences Research Council (BBSRC).

Inset images: Scanning electron micrograph of the antenna clamped by the cleaner (Alexander Hackmann); Scanning electron micrograph of the tarsal notch (Alexander Hackmann).

Reference:

Alexander Hackmann, Henry Delacave, Adam Robinson, David Labonte, Walter Federle. Functional morphology and efficiency of the antenna cleaner in Camponotus rufifemur ants. Open Science; 22 July 2015.

Using unique mechanical experiments and close-up video, Cambridge researchers have shown how ants use microscopic ‘combs’ and ‘brushes’ to keep their antennae clean, which could have applications for developing cleaners for nanotechnology.

Insects have developed ingenious ways of cleaning very small, sensitive structures, which could have fascinating applications for nanotechnology – where contamination of small things is a big problem

Alexander Hackmann

How ants use ‘combs’ and ‘brushes’ to keep their antennae clean

Alexander Hackmann

Scanning electron micrograph of the tarsal notch

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Mental time-travel in birds

ns480 — Fri, 14 Oct 2011 08:15:12 +0000

Some tropical birds collect their prey at army ant raids, where massive swarms of ants sweep through the forest and drive out insects. ̽��ֱ��behaviour of interest is called bivouac checking; it allows these birds to track the cyclical raid activity of army ant colonies.

Army ants have regular alternating periods of high and low raiding activity, and birds visit the ants’ temporary nest sites (bivouacs) to determine which colonies are raiding on a given day.

̽��ֱ��new findings published today in the journal Behavioural Ecology, suggest that bivouac checking allows birds to keep track of multiple army ant colonies, keeping account of which colonies are in periods of high-raiding activity while avoiding colonies with low-raiding activity.

Recent research has discovered that birds check army ant bivouacs at the end of the day, after they have fed at the raid. They may use the information about the army ant nest location the next day to find the ants again, thus accessing a past memory (the nest location) to fulfil a future need (bird will be hungry tomorrow), also known as ‘mental time-travel’.

Two of the authors of the study Corina Logan of the ̽��ֱ�� of Cambridge, and Sean O’Donnell of the ̽��ֱ�� of Washington, observed bivouac checking behaviour in Monteverde, Costa Rica.

Mental time-travel consists of two elements: the ability to remember past events and the ability to anticipate and plan for future events. It has traditionally been considered a quality unique to humans. However, ever since Nicola Clayton of the ̽��ֱ�� of Cambridge discovered that scrub jays (a species of large-brained crow) can remember the past and plan for the future, there have been a suite of studies showing evidence of this ability in other species as well. We now know that corvids (birds in the crow family), some primates, and possibly rats have all shown the ability to remember the past and plan for the future.

Corina Logan, said: “We suspect that future planning could be involved in bivouac-checking bird behaviour because the birds were checking bivouacs when they were not hungry, a behaviour that does not make sense until the next morning upon return to the bivouac when the bird finds the ants raiding again and encounters its next meal - a delayed benefit.”

Until recently, it has been difficult to find model systems for studying mental time travel in an ecologically relevant way. “ ̽��ֱ��fact that we might have happened on a whole new system for exploring these capacities is quite exciting,” added Corina Logan.

Certain types of birds may track army ant swarms using sophisticated memory and the ability to plan for the future.

̽��ֱ��fact that we might have happened on a whole new system for exploring these capacities is quite exciting.

Corina Logan

Glenn M Duggan FZS

White Whiskered Puff bird

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Yes

̽��ֱ�� of Cambridge - ants

Close-up film shows for the first time how ants use ‘combs’ and ‘brushes’ to keep their antennae clean

How ants use ‘combs’ and ‘brushes’ to keep their antennae clean

Mental time-travel in birds