Class Cephalopoda are a group of mollusks that include octopuses (or octopi), squid, cuttlefish and nautiluses and can be found in all the oceans of the world. They are known for their high intelligence, ability to change color and texture rapidly, advanced eyes/eyesight, defensive ink clouds and jet powered locomotion. One of the characteristic traits of mollusks is a hard, protective external shell, and although the nautilus has an external shell, most other cephalopods do not (they are either greatly reduced or internalized). In the past, cephalopods were one of the dominant forms of ocean life; today, however, we see approximately 800 species.
Octopuses, in particular, are known for their intelligence. Several studies have shown that octopuses also have a large capacity for learning. A classic experiment illustrating this is one octopus learning from another how to open a jar to get the crustacean reward inside. And aquarium owners are well aware of the great lengths that octopuses go to in order to rearrange their tanks or even escape!
A recent study published in the Journal of Experimental Biology tested octopus behavior in a new way. Since many cephalopods use visual signals to interact with conspecifics, predators and prey, images can be used to gain insight into behavior. The researchers (Pronk, Wilson, and Harcourt) were working with the Gloomy Octopus (for real), Octopus tetricus, a native of the Sydney Harbor. They set up high definition televisions next to octopus tanks and showed them images of crabs and other octopuses. They then evaluated the octopuses response (excitable, aggressive, etc).
It isn't that this TV method hasn't been tried in the past, it has and it failed. The cause is likely the fault of the TV and not the octopus. Remember my mention of the sophisticated eyesight characteristic of cephalopods? Well, those sophisticated eyes looked at that old 26 frames per second TV and made no sense out of it. But high def TVs that run at 50 frames per second? Oh yeah!
When the octopuses were shown images of their favorite food (and one of mine), crabs, they rushed towards the TV and tried to attack it. When shown images of other octopuses they retreated to the back of their aquarium to hide. After several weeks of repeating the experiment the researchers got a good picture of the octopuses' "mood swings." Individual octopus tended to react in a consistent way to these stimuli within the same day, but within a week their behavior could be very different. The octopuses were also given images of items they had never seen before, such as a jar. Sometimes they would be bothered by the jar and other times they would be curious and go take a look at it. Overall, the authors concluded that the "gloomy octopus show temporal discontinuities, and hence display episodic personality." Basically, they are moody little things.
So now there is an excuse to buy fancy new tech -- to play with octopuses! I mean...ahem...to test octopus behavior and intelligence.
The paper abstract: http://jeb.biologists.org/cgi/content/abstract/213/7/1035
(image from scuba-equipment-usa.com)