Summary: The Sydney octopus (Octopus tetricus) occurs in unusual numbers on a shell bed of its prey remains that have accumulated as an extended midden where additional octopuses excavate dens. Here, O tetricus are ecosystem engineers, organisms that modulate availability of resources to other species and to their own species by causing physical state changes in materials. A community of invertebrate grazers and scavengers has developed on the shell bed. Fishes are attracted to the shell bed in numbers significantly greater than in nearby habitats. Large predators, including wobbegong sharks, were attracted to and fed on concentrations of fish, inhibiting the activities of the original engineers, the octopuses. Positive feedbacks included the accumulation of shell debris, increasing shelter availability for additional octopuses and aggregating fish. Negative feedbacks included reductions of nearby prey size and availability, aggression among octopuses, and predator limitation to octopus activity that would otherwise maintain the shell bed.
David Scheel, a biologist at Alaska Pacific University; Peter Godfrey-Smith, a philosopher of science who has appointments at City University of New York and the University of Sydney; and Matthew Lawrence, an Australian diver, collaborated to record interactions between common Sydney octopuses off the Australian island of Tasmania.
Their method was to put cameras on the sea floor in areas where there were plenty of these octopuses and then comb through hours and hours of video.
They aren’t done yet, but Dr. Scheel presented some of their initial findings in Anchorage at the annual meeting last month of the Animal Behavior Society, and they have about two dozen examples of octopuses signaling their aggressive intent.
exciting stuff with the NY Times article. about our unique octopus site .
from a post i put up on tonmo a number of years ago , significant things have happened, in a good way .
without tonmo i probally never would have made the inital contact with PGS and then david Scheel , and Stefan ... so well done. to this forum and the moderator.
i have really enjoyed working with people from a totally different background , . it has been a great learning exeperence .
i still love visiting octopolus . as i never know what will happen or how the occys will behave . and as ive said in previous posts their moods can change . for no aparent reason .
i thought id scare some recent pics from a dive i did at Nelson bay. we came across a blue lined octopus that seemed quite excited , i managed to get a few pics , but all the time i was shooting him i had to back peddle , as the plucky little guy was swiming straight for me . at one stage he even landed on the lense of my camera . very interstering . while this was going on i was a bit distracted .
you can understand my suprise when i turned away from the occy to seem my dive buddy swiming up to the occy , glove removed , and was just about to try and touch and play with the blue lined octopus !!!
i very quickly gave signals of danger , dont touch , ect and when we got out from our dive , i explained to her the potential danger of blue lined octopus .
I am glad your dive buddy understood your signals before he reached the octopus. Your helicopter trip to the decompression chamber was enough diving excitement for me to read for a lifetime! More pictures coming?
As Matt says, all the science at the Octopolis site came initially out of Matt's TONMO posts. Crissy Huffard (mucktopus on TONMO) told me about Matt's posts and I got in touch with him. Then David Scheel saw an article about it, over in Alaska, and he contacted me. Now Stefan Linquist is on the team also.