3 replies to this topic

[gcbryan]

I went diving a few days ago with the local sixgill (shark) expert from the Seattle Aquarium and we were also discussing GPO's. I had a question that I forgot to ask so since he had asked me to email him a picture that I had taken of something else (Vermilion Rockfish) I asked him my GPO questions.

I'll just post my question and his answer. Maybe it will be of interest and maybe fill in some details for some of the PNW divers on this board who might find this interesting.

Question:
Regarding the GPO beak. What is it's primary use? Is it to break open things or primarily to inject the enzyme that paralyzes and disolves muscle tissue? To put it another way, when I see crab shells outside of a GPO den did the tentacles pull the shell apart or did the initial crack come from the beak?

Answer:
The primary use of the beak is for tearing tissue to eat. It probably is used to open some crabs shells as well. The octopus can drill with its radula to make a hole in clam and crab shells. It also can inject or spit a venom that acts as a neurotoxin and as a proteoltyic enzyme. The venom can kill its prey and start a digestive process that allows the octopus to separate all the crab tissue from its shell.

Very large octopus can pull crabs open. Most medium to large octopus will drill a small hole in the rear of the crab's carapace to inject venom. This kills the crab and makes the rear of the shell easier to pull open. They may also bite near the rear edge of the shell. Look at crab carapaces you find near an octo den and hold them up to a light. You should see a small hole near the rear edge of the shell ~1/16 in. diameter

[6Gill]

Another fact to add is that the beak is the only hard part on an octo. This allows the full grown GPO to fit through very small openings such as cracks in the rocks.Somewhere there is video of a GPO(approx 85lbs) entering and travelling through a 2" diameter clear acrylic tube.their ability to change colour along with the ability to 'shape shift' is another thing that makes them so intresting to observe underwater.

Eric

[gcbryan]

Another fact to add is that the beak is the only hard part on an octo. This allows the full grown GPO to fit through very small openings such as cracks in the rocks.Somewhere there is video of a GPO(approx 85lbs) entering and travelling through a 2" diameter clear acrylic tube.their ability to change colour along with the ability to 'shape shift' is another thing that makes them so intresting to observe underwater.

Eric

Good points. I once saw a rather large one on China Wall retreat into a small crack in the wall. It looked more like smoke being sucked into a hole.

[Brinybay]

...
Somewhere there is video of a GPO(approx 85lbs) entering and travelling through a 2" diameter clear acrylic tube.
Eric

That would be "The Octopus Show"