By Jody Bourton

Earth News reporter



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Octopuses are excited by high definition television, say scientists.

In experiments evaluating how the creatures react to moving images, the animals responded far more vigorously to HDTV than standard definition TV.

It appears that standard definition moving images are not sufficiently "convincing" for the sophisticated cephalopods, say the scientists.

Researchers can now use HDTV as a tool to study elements of their behaviour, such as personality.

Details of the discovery are published in The Journal of Experimental Biology.

It was a case of the technology not being up to the relatively high standard of octopus eyesight

Ms Renata Pronk

Macquarie University, Sydney Australia

Octopuses appear to be intelligent animals, that respond to their environment with brilliant colour changes.

In theory, showing moving images to them, of predators, prey or other octopuses for example, would be a good way to study their behaviour.

But in previous experiments, cephalopods - the family containing octopuses, cuttlefish and squid - have not responded to standard quality video images.

This team of researchers decided to test how octopuses reacted to HDTV, which has roughly five times as many pixels as standard definition TV (SDTV).

Ms Renata Pronk from Macquarie University, Sydney, Australia and colleagues collected gloomy octopuses (Octopus tetricus) from Sydney Harbour, transferring them to a tank at the Sydney Institute of Marine Science.

There, they exposed the octopuses to three HDTV videos, recording the animals' response.

One video showed a crab, a natural food for octopuses, running across the screen.

The second video showed another octopus and the third a simple jar.

The octopuses reacted differently to each video, but their behaviour was not consistent over time.

For example, on one day an octopus would react excitedly to the crab video, but it would show little interest on another day.

This demonstrates that gloomy octopuses have "episodic personalities", say the researchers, which means their personality varies over time.

The discovery that octopuses react to HDTV will now allow researchers to study aspects of their personality and behaviour further, says Ms Pronk, including why octopus personality appears to be variable and short-lived.

High standards

"We developed a method of showing video to an octopus, which was the first time this has been successful with any cephalopod," says Ms Pronk.

The octopuses likely react to a few features of HDTV, she says, including its higher definition and higher frame rate, and the refreshing of horizontal lines across the screen at the same time, a feature called progressive scan that is not included in SDTV.

"It was a case of the technology not being up to the relatively high standard of octopus eyesight."