Thanks
@robyn. As with octopuses, I am cautious with my fingers and I do think Zilch may want to nibble. Sometimes he attaches to my fingers with multiple cirri and pulls his body closer. When I try to free my hand he will come slightly out of the water before releasing. When he does this I am never sure if he is simply anchoring to my fingers, if my fingers taste like food or if he is just curious about how my fingers would taste.
I suspect these guys may have individual personalities and am not surprised you found them to be more intelligent than they look (my son thinks they look "dumb") but it is hard to tell much about intent with an animal that does not change color, body posture or eye expression. One consistent observation I am trying to translate is his rise to the surface when I approach the tank (usually trying to get a picture of how low he is
). I am assuming he cannot see well enough to identify me as an individual and he does this before I put my hand (or even if I don't) in the tank. He may be expecting food but will do this even if he is not hungry. I need to experiment and see if he rises when Neal approaches as well (I am the primary feeding slave).
I think they (or at least Zilch) may be far sighted and can visually detect movement better at a distance, akin to a fixed focus lens setup for landscape rather than portrait (Brownie cameras come to mind
). The kitchen is about 15' away (as the crow flies) and he seems to see movement there very well. If he is awake, he will start pacing at the front of the tank when someone is moving around in the kitchen. If he is sleeping he does not seem to notice anything and it takes a good bit of splashing and water movement to "wake" him up. When I am in front of the tank and place my fingers inside at the top, he seems to have a bit of difficulty determining their location. Usually, he goes to his front corner and extends his cirri but does not come directly to the center to my fingers. If I am patient he will eventually find my hand but it takes several cross tank (back to front) attempts along with some odd navigation (like a tacking sailboat).
I suspect Zilch will become neutrally buoyant as he grows (I want to try to figure out sex but don't want to take him from the water). It would make sense that they create more fluid as they grow and his depth accomplishments have come after detectable shell growth. Do we have a clue on what the fluid is composed of and what foods might encourage production?