Swimming ants don shades to save their eyesight

Dec 17, 2013

Australia's unusual swimming ants take their own 'sunglasses' when they go to the beach – to shield their sensitive eyes from bright sunlight.

Scientists at Australia's Vision Centre (VC) have discovered how the world's only swimming ants manage to cope with extremes of light and darkness, and how they navigate between their nest and food sources.

"These ants are found in North Queensland, where they establish nests in the where ocean and land meet," says Dr Ajay Narendra of The VC and the Research School of Biology (RSB) at the Australian National University (ANU).

"They are the only ants that we know of whose daily activity is tidal-dependent. Instead of relying on temperature or light intensities like most ants, their foraging activities are based on the tides."

Dr Narendra explains that the ants are active during low tides with most ants returning to the nest before the water level rises: "So they're faced with the task of being active at a wide range of light intensities and as a result, developed striking visual adaptations to cope with it."

The researchers first found that the ants' structure is similar to those of strictly night-active ants. To capture more light, they developed larger lenses and wider vision compared to the day-active ants.

Due to their wider vision cells, the swimming ants also have a special way to protect the cells from burning out when they are active in bright light during the day, Dr Narendra says.

"In bright conditions, they restrict the amount of light that reaches their retina," he says. "The cells in their eyes move closer, forming a 0.5 micrometre wide aperture – 500 times thinner than a human hair. This makes their eyes less sensitive during the day.

"And at night, the cells move away, opening up the aperture to nearly 5.0 micrometres in width, making their eyes more sensitive at low light."

Dr Narendra says that the formation of such a narrow aperture for the swimming ants is quite extreme, and scientists know of no other ant that does the same.

"This method is similar to how humans protect their eyes," he says. "Our pupils dilate in the dark and narrow when it's bright.

"Something similar happens in the ants' eyes. This technique is crucial for all animals that experience a wide range of to protect their vision."

The group is at present studying the swimming behaviour in these .

Explore further: New England Aquarium offering penguins 'honeymoon suites'

More information: Narendra A, Alkaladi A, Raderschall CA, Robson SKA, Ribi WA (2013) Compound Eye Adaptations for Diurnal and Nocturnal Lifestyle in the Intertidal Ant, Polyrhachis sokolova. PLoS ONE 8(10): e76015. DOI: 10.1371/journal.pone.0076015

Related Stories

Ants pay high price for night life

May 28, 2013

(Phys.org) —Despite being night creatures, Australian bull ants have trouble finding their way home in the dark. Scientists at Australia's Vision Centre (VC) have found that bull ants that travel at night ...

Ants use 'photo library' to find home

Jul 16, 2013

(Phys.org) —Ants keep a collection of 'snapshots' taken close to the nest so they can find their way home from unfamiliar locations.

Study says nocturnal ants have evolved night vision

Oct 06, 2010

(PhysOrg.com) -- Researchers studying the eyes of different Australian bull ants have found the first evidence of adaptation of visual structures within a single species to distinct light intensities.

Recommended for you

Telling the time of day by color

Apr 17, 2015

Research by scientists at The University of Manchester has revealed that the colour of light has a major impact on how the brain clock measures time of day and on how the animals' physiology and behavior adjust accordingly. ...

Aphrodisiac for fish and frogs discovered

Apr 17, 2015

A supplement simply added to water has been shown to boost reproduction in nematodes (roundworms), molluscs, fish and frogs – and researchers believe it could work for humans too.

Evolution puts checks on virgin births

Apr 17, 2015

It seems unnatural that a species could survive without having sex. Yet over the ages, evolution has endowed females of certain species of amphibians, reptiles and fish with the ability to clone themselves, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.