Kooah's Hatchlings - O.briareus

DWhatley

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Since I am seeing some parallel behavior, I will continue to post here for growth observations and thoughts. This week both octopuses started coming out on the wall clear of their live rock when the lights are turned off and it is about 11:00 PM.

Within a day or two of each other the "twins" seem to have become aware of things breaking the surface. At first we noticed Tatanka grabbing for the feeding stick at the water line and assumed it was Neal's fingers that attracted him but his next similar feeding and similar action by Cassy make us think they are newly detecting the water breaking at the surface.

Tonight, Neal kept Cassy's shrimp at the surface and she climbed up the back wall to attack it (she has been coming out further from the live rock all week). She considered taking his fingers along with the shrimp (held in different arms) but decided the shrimp was large enough for dinner after several pulls. We expected that eyesight might have improved for this distance but the arms still waved only in the general area of the food until there was contact (arm outstretched about 8 inches). This is the first time we have seen her near the surface (there is a 2" glass plate in the back at the water level in this tank, originally to support lights, and she was suspended from it hanging upside down).

We tried something similar with Tank (his aquarium is deeper) and he stretched his arm out at least a foot but decided the food was not what he was looking for when he touched it with the tip of an arm. He seems to have better eyesight or detects the surface break better as his arm was well position and did not flail in the water column. It may also be that my thought that they are very farsighted comes into play because the surface was further away. When the shrimp was offered on the feeding stick and placed close to the mouth, it was accepted.
 

DWhatley

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The twins were both out around 10:00 tonight so I fed them early and experimented a little with their vision. I can't quite get a feel for where they can focus. Tatanka inked at movement 10' away (a measured distance from the bottom of the stairs to the tank) the other night when I startled him but neither can see the shrimp at the end of a feeding stick. The seem to detect the stick better than the shrimp but I don't think it is sight. They also seem to detect that the shrimp is in the water but fail to realize a live crab is being offered by hand. It is interesting to see that the serpents (particularly Pesky and PeskyToo, the red brittles) know immediately when food is being offered (even live that they don't eat) and have a better chemical detection of location.

Tonight Cassy completely misguessed where the shrimp was but the second I scratched the stick on the live rock she was all over it.

I also noticed tonight that Cassy often hangs upside down from an overhang. I mentioned this odd behavior in her Kooah's thread and don't know what to make of it. We have not noted Tatanka taking this pose and he is in the original hatching tank where Kooah resided. I have considered the possibility of a male/female difference but KaySoh was also female and did not take this posture.
 

Nancy

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I never noticed my bimac Ollie to have any trouble seeing anything at any distance, close up or outside the tank (to maybe 10 feet, but not sure).

I enjoyed holding up a fiddler or the occasional crawfish outside the tank so she could see it. She could recognize what it was very well, and was clearly excited, wiggling about. I would release it into the water, and she would be all over it. Pieces of thawed frozen shrimp were fed by the feeding stick, and she saw that very well, too. Maybe the vision capability differs by species.

D, we've had other octopuses that sometimes liked to hang upside down. Maybe it's just individual preference.

Nancy
 

DWhatley

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Monty has no difficluty seeing close up but I have not yet come up with an interesting test to see how far away he can see (he does notice the dogs when they go by his tank and he has intently watched me pet the wolfhound who's head is above the tank table height). I have noticed sight issues with all the briareus and they appear to be quite far sighted. This may or may not be related to them being nocturnal hunters but the mercatoris did not seem to have the same kind of vision. SueNami could detect my son at the top of the stairs which is probably another 15' away (the 10' measurement was at the bottom). I am quite sure that their arms are very sensative to vibration and Cassy's reaction tonight was an example.

What I find kind of interesting is that Kooah showed this behavior (none of my others, any species, have), Tatanka does not (or at least not yet) but Cassy does. I think Cassy's arms are thicker near the head than Tanks but I don't know if that is relevant.
 

DWhatley

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First pets

Somewhere around 4:00 AM the dogs wanted out and I noticed Cassy sitting on the wall so I initiated eye contact. She could definitely detect movement 2' away and bobbed to get better focus (or at least that is what thinking is on the bobbing). I opened the tank and wiggled my fingers but got no response so I moved closer. When I was about 2" away she knew something was there from the current and ducked down into the LR but did not go far. After several disappearances she and made herself as big and white as a little octo can be and reached for whatever was making the current. On contact she withdrew her arm rapidly, similar to the other contacts but this time she moved to a new location, closer to me. I slowly moved my finger to her eyes and she let me pet her. At one point she came partial out from her cover and reached for my finger but, again, on contact quickly withdrew. However, she let me pet her again and moved so that I could pet her whole mantle. The whole interaction lasted about 20 minutes.

Afterwards, I looked to see if Tank was out but he was nowhere to be found.
 

DWhatley

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5 months and two days and all is well

Mamma Cass and Tatanka continue to grow and now look like the smallest ones we traditionally see from Tom. They are still smaller than any I have purchased but well on their way to looking like real octopuses. The are not out in the light still so I can't sex them but I can often see that they are awake before lights out and have fed Cass on the back wall under the rocks a couple of times and Tatanka at sunrise once or twice. Slowly we seem to be getting there. They are touching more but still not social.
 

DWhatley

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Changes at 5 months

At just over 5 months old we are seeing dramatic changes in socialization and hunting accuracy. Almost overnight the two surviving octopuses are either out or allow themselves to be seen at 6:30 PM feeding time. The confirmed male has started dancing on the front glass at night and both are much more accurate with their attempts at capturing food in the water column (vs hunting the rock by feel). We are not sure if their eyes are now better developed or if their coordination has dramatically improved but the difference is remarkable.

Tatanka remains more curious than Cassy and will react without running away to fingers moving along the aquarium wall while he is walking along it. I won't say he follows the finger but he does reach to for it. Sometimes he uses multiple arms to try to touch it and sometimes he pulls away when there is nothing there to touch.
 

Level_Head

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They sound like they are faring well after a lifetime in your care.

The eyes of mammals in general (and humans in particular) are close to adult size at birth. Our eyesight does not change much during normal growth. But octopus eyes go from near-microscopic to near-human in size (and obviously the squid branch has gigantic eyes). Thus, the vision changes throughout the animal's life, though the changes (like the growth rate) would be more dramatic in the early stages. The lens distance will be different, the image will fall on a greater number of retinal receptors and so forth. (Their lenses don't flex, they move forward and backward to focus -- and the ratio change rate of different optical refraction around the edge of the lens -- a very clever system -- would have to change as the lens grew.) I'm not surprised at the evidence you are seeing.

Daq (in Chapter 2) knew early on that his eyesight would improve as he got bigger. Fortunately, he didn't have to hunt for his supper.
 

DWhatley

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So when am I going to get to read about Daq?

I love the research you have done for this. I am extremely weak in biology so it is comforting to know that my observations appear to have some biological merit. What is seemingly odd is that the focal range has changed in roughly 1 week's time.
 

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