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. I thought I posted several of my not so great pics from the Mote aquarium (TONMOCON II - Sarasota, FL) but can't seem to locate them so I am posting them here. As I understand it, these two were caught together as juveniles and had been at Mote for over a year. The size you mention almost mandates that Gertude is a Vulgaris as the others found in the Keys (and the East Coast) are much smaller. Additionally, not all octos have midden piles but the Vulgaris is famous for them (and using them to locate octos)
Diving Molassas? It would be a dream come true for me to have a "pet" that I visited like that so I hope she will interact more. With the aquarium kept, we often use a feeding stick and you might try something similar. A common bamboo skewer with a dead 3-4 inch shrimp on the end could be offered. When Octane (Hummelincki) is being stubborn, sometimes we place the shrimp under his webbing rather than just on the arms (octos have arms only - squid and cuttlefish have arms and tentacles).
Octos have only one siphon but most can move it to either mantle opening (I believe the GPO's - Giant Pacific Octopus - is different)
Yes, Grouper find octos an excellent meal and after the eggs hatch she will most likely meet her end that way. One of our members in Italy posted this link to an excellent German version of Octopus Volcano. It is rather long but well worth watching and features Vulgaris living near a live volcano in Italy:
http://www.tonmo.com/community/index.php?threads/8626/&highlight=WDR