Octopus breathe through gills that should be suspended "weightless" under water for all the tiny lamellae to be in touch with oxygenated water, in very much the same manner as fish gills behave. Taken out of water the surface area drastically diminishes to an unsustainable level and the octopus suffocates. This limits the time spent outside of the water to minutes rather than hours before the animal dies. Dessication is a compounding factor. In all, an octopus can travel from tidepool to tidepool and back to the sea, but I would suggest limited to distances one would measure in feet. Anyone have (anectdotal) evidence otherwise? I'd be interested
Several other factors enter into the equation including size, temperature, and adaptation to intertidal habitats.
Small individuals (species) can maintain gill configuration better than larger individuals.
Nocturnal species can make it further than animals cooking in the noon day sun.
There are a few intertidal species that hunt from tidepool to tidepool and are better adapted to being exposed. I've followed individuals perhaps 20 m crawling over exposed reef flats at night, but they were at least staying moist.
The farthest I have seen an octopus that escaped in the lab travel was a large bimac that made two circuits of the lab before we were able to bag it.
If I am not mistaken I think I remember Roland Anderson, formerly of the Seattle Aquarium, tell me that he has seen GPO's survive up to 20 min out of the water in moist environments. Some species also seem to be very tolerant of compromised oxygen exchange. I know, for instance, that O. rubescens can survive at least 3 hours in completely anoxic water.
We've had them out for some hours! One (Harry) escaped his tank and was found (during a 10.30pm check) halfway up the stairs to the staff room (a fair distance) and he still had enough energy to fight the aquarist for 3/4 of an hour!
It isn't "normal" for their tidepool (your tank) to be externally restocked with crustaceans, so the preserved trait is to jump to the next one after finishing the available meals; it is normal feeding behaviour, which could be interpreted as curiousity as well
OB nailed it. For some species, this is normal behavior. Reliable records of octopuses leaving the water go back to Aristotle. Much lessess reliable to Pliny the Elder. I've observed four species out of water or leave the water in nature. Some were hunting, some were trying to get away from me as I photographed them.
I have had male O. hummelincki try to come out of the tank when they were near the end of senescence but my first O. bimaculoides (Diego) seems to want to put his arms (only the front two, L1&R1) and the top part of his head (not mantle) out of the water on a regular basis. He seems to have found it amusing to shift his funnel to point up from under his webbing then raise his front arms and fire. He is getting pretty good at this and now manages to get me wet (initially his range was way short). He does not seem to be upset (coloration is normal) and he will then play with my hand and does not seem to be interested in coming out further but he does this several times a week.