by Richard Macey

Sharing a movie with an insensitive eight-armed animal may not be every woman's perfect date.

Renata Pronk did it for science, and made two significant discoveries.

Her unsettling news for Christmas revellers preparing to tuck into seafood platters is that octopuses can watch television and understand at least some of what they see. Discriminating viewers, however, they enjoy only high-definition programs.

In a second finding, the Macquarie University marine biology researcher resolved a long scientific debate, discovering that octopuses, despite their intelligence, lack individual personalities.

"Octopuses," Miss Pronk said, "are very smart. I have seen my octopuses open Vegemite jars by unscrewing the lid. They can find their way through mazes to reach food rewards at the end.

"And they can learn simple puzzles", recognising that symbols, such as squares or circles, mean food is available.

"The definition of personality," she said, "is having repetition in your responses, for example, being consistently bold, or consistently shy, or consistently aggressive."

To resolve the debate she collected 32 common Sydney, or gloomy, octopuses from Chowder Bay, near Mosman, and showed them a series of three-minute videos screened on a monitor in front of their tank.

One video featured a crab, an octopus delicacy.

A second starred another octopus, while a third had a "novel object" they would not have seen: a plastic bottle swinging on a string.

Miss Pronk then watched each octopus for any consistent response pattern, such as boldness or aggression.

When the crab movie was screened "they jetted straight over to the monitor and tried to attack it", she said, adding that was strong evidence they knew they were watching food.

When the octopus movie was screened some became aggressive while others changed their skin camouflage or "would go and hide in a corner, moving as far away as possible".

On viewing the swinging bottle, some puffed themselves up, just in case the object was a threat, while others paid no attention.

But significantly, when the experiment was repeated over several days, she found no consistent response from any octopus. Such random responses implied octopuses have no individual personalities.

She suspected previous efforts to show movies to octopuses failed because their sophisticated eyes were too fast for the 24-frame per second format of standard-definition video.

"They would have seen it as a series of still pictures," said Miss Pronk, who had success using high-definition, operating at 50 frames per second.

She confessed that her work made it difficult to dine on octopus. "I know how smart they are. They are beautiful animals."