25 May 2011 Last updated at 11:38

In Pictures: Cuttlefish camouflage

An Australian giant cuttlefish camouflages (c) Sarah Zylinski

The effectiveness of the Australian giant cuttlefish's camouflage has been examined by scientists. The animals are known for their ability to both blend-in for protection and stand-out to attract mates.

A cuttlefish switches from display to camouflage (c) Sarah Zylinski

In this photograph a male rapidly switches from breeding signal to camouflage as a diver approaches. Cuttlefish are masters of changing colour but are actually colour blind according to scientists.

A camouflaged giant cuttlefish (c) Sarah Zylinski

By focussing on their patterns rather than overall body colour, scientists aimed to understand more about the cuttlefish's amazing transformations from their own perspective.

Professor Justin Marshall of University of Queensland photographs a cuttlefish (c) Sarah Zylinski

Biologists from the UK, US and Australia quantified how well the cuttlefishs' patterns match their background by analysing how often the patterns repeated on the animals' surface compared to the immediate environment.

A close up of a signalling male (c) Sarah Zylinski

The mathematical analysis showed that camouflaging cuttlefish's patterns occured with the same frequency as patterns in the environment. Signalling males meanwhile stood out by diverging from these patterns with dramatic white stripes.

The field site near Whyalla, South Australia (c) Sarah Zylinski

Australian giant cuttlefish (Sepia apama) are the largest in the world at up to 50cm across and they live off the southern coast of Australia. Each year they come inshore to breed and hundreds can be encountered on a single dive.

A male cuttlefish displays to attract a mate (c) Sarah Zylinski

"Male giant cuttlefish embark on elaborate displays to each other, to battle out the right to mate with females, and to the females themselves," explains ecologist Dr Sarah Zylinski. "This involves passing bands of dark [cells] over their bright blue-green and white-striped bodies in waves."

A cuttlefish displays an elaborate passing cloud signal (c) Sarah Zylinski

Researchers believe the cuttlefish rely more on high contrast patterns for visual recognition during the breeding season. Here a male warns off a rival with an complex signal said to resemble passing clouds.