ScienceAlert Homepage

A yellow crazy ant (Anoplolepis gracilipes)
explores the foliage.
Image: Ajay Narendra

A young researcher says learning about how ants navigate the landscape could inform the development of ‘seeing’ robots.
 
Love bugs? Dr Ajay Narendra certainly does. It’s this fascination and respect for all creatures — great, small and creepy crawly — which sparked his passion for ants.

“Ants caught my interest primarily because of their diversity, numbers and stunning behavioural repertoire,” says Narendra, a postdoctoral fellow at the ARC Centre of Excellence in Vision Science, based at ANU.

Narendra’s ant intrigue led to him watching ants for long periods of time and seeking out information to satisfy his hunger. The more he learned, the more interested he became. During this quest, Narendra met ant taxonomist Prof TM Musthak Ali from the University of Agricultural Science in India. The expert took the young enthusiast under his wing, training Narendra in the art of taxonomy over many summer holidays.

It was because of this training that Narendra was invited to be a part of a cumulative impact assessment, where he worked using ants as ecological indicators to understand the impact of disturbance on ant diversity and distribution.

More recently, he has been investigating the ways insect sensory and navigational systems have evolved to suit different niches, either along the gradient from day to night (temporal niches), or in vastly different landscapes (ecological niches).

“Social insects like ants, bees and wasps leave their home every day in search of food and then manage to return home with remarkable precision,” he says.

The scientist says that ants that do not use pheromone trails rely either on visual landmarks, or on a combination of step counting to measure distances and a sky compass to estimate direction. The latter strategy, called path integration, ensures the insect returns home by the shortest distance.

“Ants have a stunning ability to head home by taking the shortest possible route, despite the fact they would have made a tortuous path to find the food source in the first place,”  Narendra says.

He says this behaviour has been well documented in ants that live in the saltpans of Tunisian Sahara, one of the study sites from his PhD. Incidentally, he found that ants in Australian deserts exhibit different and unique navigation styles. Ants in Central Australia interweave around grass tussocks and trees to establish idiosyncratic routes that they adhere to. “Path integration in these ants is used as a back-up strategy only in the absence of familiar visual information,” Narendra says. He says the most stunning discovery was that no matter how far the ants travel to find food, path integration system works for an exact halfway distance towards home in the absence of visual cues.

Because these different kinds of navigation behaviours were found in unrelated species, the researcher wondered if the variations were merely species differences or were they influenced by habitat complexity.

Narendra and his colleagues recently discovered that a set of closely related bulldog ant species occupy the same ecological niche but different temporal niches, which enables them to now test whether habitat complexity plays a role in the design of navigational systems. To test this, Narendra has been awarded an Australian Postdoctoral Fellowship from the ARC in 2009.

Their investigations into the visual systems of these ants indicate that habitat complexity plays a vital role in the design of navigational systems. They found that each bulldog ant species had evolved strikingly different vision-systems that correlate with their time of activity. “The day-time ants have small facet lens diameters and narrow photoreceptors in their eyes to deal with the brighter environments, while their nocturnal cousins have ‘night-vision equipment’ with larger facets and photoreceptors that are five times wider,” Narendra says.

“This discovery gains paramount importance since it had been thought impossible for closely related animals to occupy different temporal niches, as it requires substantial physiological adaptations that could not have evolved in such species.”

Narendra believes that understanding navigational strategies exhibited in different temporal niches has implications for the design of robust and flexible artificial intelligence for unpredictable environments. More generally, he hopes to share his passion and build a greater appreciation of ants. “I hope ants receive the recognition from the general public for the stunning behaviours they exhibit.”

The young researcher received some recognition himself in 2008, taking out one of the Young Tall Poppy Science Awards.

Now Narendra plans on continuing research into the ant kingdom. Next on the agenda is identifying the navigation system used in different temporal niches, understanding the relation between task specialisation and visual structures in ants, and the role of temperature and light in establishing temporal niches.

But if that all sounds too technical for your taste, fear not. Narendra is also fond of popularising ants by conducting regular walking tours around Canberra. He’s been pleasantly surprised at the number of people eager to learn more about the tiny creatures making their way around footpaths and backyards. “It was a huge surprise to see such numbers turning up to watch ants, which was fantastic.”