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[Octopus Eggs]: Legs - O. Mercatoris

Britani

Cuttlefish
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Dec 3, 2014
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19
5/17/15 - We seem to have hit our mortality spike this weekend. I just had the water tested again on Friday, so I know quality is not the cause. As of tonight we have found 24 dead, but I still counted 19 alive - bringing the total that we know about to 43. The vast majority of the ones that we've found dead (with the exception of the one that I posted a picture of on 5/15) are very tiny. The first 4 that we found seemed to be a case of wrong place wrong time, and they weren't noticeably smaller than the others. I'm wondering if these others were perhaps the last eggs to hatch and were slow to hatch because they were so small or maybe they are so small because they were at the very end of the hatching cycle and just weren't as healthy? I had read on other journals that there is usually a rolling hatch of approximately 7-10 day, but Legs' eggs hatched for somewhere around 18 days. It was a full 21 days before we were sure there were no more eggs. Regardless it is hard to see them die.

Today the kids shook some shrimp out of the seaweed at the beach and we brought it home to offer the hatchlings. Some accepted being hand fed and seemed to try to eat it, but the shrimp are still quite a bit larger than the hatchlings. Others worked (some successfully) to catch them on their own after we added some to the tank. I'm not sure how much they managed to eat, but it was nice to offer something different. We also added another bottle of tigger pods, but this time I turned off the filter for about 20 minutes to try to give them a chance to secure a location in the rocks so they didn't just get sucked right into the filter. I cleaned the filter before I added them, so I'm hoping that will help give us an idea if the hatchlings are catching and eating them, or if they are just flowing right into the filter.

It seems to me that with our experience, the small hatchlings still come to the glass in the evenings, but the ones that are a little bigger seem to be staying hidden/camped out in the rocks. I am beginning to notice some frequent hiding spots, so I'm often able to count more than just the ones on the glass. This past week I've noticed that the ones I'm seeing on the glass are noticeably smaller than the ones on the rocks and small even compared to the size of the early hatchlings when they first hatched. This is why I'm wondering if the later hatchlings just aren't as hearty as the earlier ones.

Here is a picture of one of the hatchlings trying to eat the shrimp.

IMG_4713.JPG
 

DWhatley

Kraken
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Be watchful with shrimp larger than the hatchlings. Keep in mind that I often call octopus the "true chicken of the sea" as everything eats it (probably more so with squid). Predator vs prey is often size related as well as who is the stronger or most clever (clearly octos win on the last two). You can improve the direction by injuring the shrimp. I needed to do this at the end of Jabba's (cuttlefish) life (winching every feeding) as he would not eat dead, knew the difference but could not catch healthy live. Some shrimp (peppermints specifically) will hunt in packs and target larger prey. I have not seen the shore shrimp do this though but it merits watching when you add live to the tank.

If they follow my O. briareus example (these were in a 60+ gallon tank vs the nets for O. mercatoris so different species but similar environment), they should start learning feeding time and start to show up in specific spots about now. Tatanka (originally named Sitting Bull - name changed to the Indian version) would come and "sit" in a specific corner of the tank almost nightly once we established a routine.
 

Britani

Cuttlefish
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DWhatley - I have a few questions for you.

1. I have gone back to leaving the red light on all the time, but have also put on the regular lights in addition during the day (from about 7am - 4pm). Is this the right thing to do?

2. How often would you feed them at this point? I know that they are supposed to hunt at night - so I try to feed them for the last time right before we go to bed so that it is definitely dark out and "night", but we've been trying to feed them 3x/day, but definitely once in the morning and once at night.

We try to use the pipettes to blow cyclops or mini mysis right to them, but we hardly ever see all of them at feeding times, so I also blow some around the rocks. It's so hard to know if they are eating it or not!

Aside from injuring the shore shrimp before adding them so they can't bother the hatchlings, do you have any other suggestions on how to try to minimize the mortality spike? I know it's unrealistic to think they won't die, but I just want to make sure we're doing all that we can.

Thanks AGAIN for all your help/suggestions!
 

DWhatley

Kraken
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I wish I could offer additional suggestions but you are doing all I can think of. I mentioned that the survival rate is very low. We have seen O. bimaculatus (cold water species) survive in greater numbers but our few recorded Caribbean successes have resulted in very few hatchlings surviving to adults. Predation, cannibalism and feeding (or not eating enough or not eating the needed foods) are thought to be the main causes of mortality. If you are finding the bodies, they clearly are not being eaten. Cuttlefish seem to be similar in that they either eat and survive or don't eat and die tiny but what gets them eating the proper quantity is unclear. Given that feeding seems to be the major impact on mortality, I would continue feeding multiple times a day at least until they can eat a whole shrimp.

As far a lighting, I am not sure there is a "right" thing. If you want to see them you will need some kind of daylight lighting. As long as they have a dark hiding place and no or only red lights at night, this seems to work fine. Leaving the red light on during the day does nothing for the lighting. I did it to avoid yet another timer. Not turning the red light off during the night acclimates them to not total darkness at night and provides the opportunity to view them. I believe they can detect the red light (it may matter on frequency and intensity) but it is accepted as night (my guess equates it to the amount of luminescence from the full moon). If the light is turned off at night, they seem to learn this pattern as well and weight for total darkness to hunt.
 

Britani

Cuttlefish
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Dec 3, 2014
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5/24/15 - True to what everyone else has said, most of our hatchlings have died. We have counted 48 that have died, and seem to have at least 2 that are still alive. There doesn't seem to be a correlation to anything as to why they died which is incredibly frustrating. The ones that are still alive still seem incredibly small. Anyone have any thoughts on how long it takes before you see noticeable growth? I know that part of why they seem so small is that they curl up so small when they want to, but even when we pipe mini misys to them and they stretch out they are still small.

We came home tonight to find Legs had FINALLY come out of her den - and, just like everyone said, she was happy to curl up on our hand and died within about 40 minutes. It was so hard to see her go, but we were so thankful to finally get to interact with her and see her - this was the only time she had come out of the den since we bought her!

We are hoping that we can manage to keep these last hatchlings alive, but only time will tell.

Here is our last picture with Legs.

IMG_4731.jpg
 

DWhatley

Kraken
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:fingerscrossed: that the remaining hatchlings survive. I remember thinking they did not grow as I expected (even the O. briareus) for the first month or two and then finally put on a growth spurt.

Somewhere there is a (or several) key(s) to better survival but we have not found it. It is why I try to mention what we have seen not work and encourage experimentation with new foods. We think only between 1 and 2 percent survive in the wild but really can't quantify that. Theoretically, we should see better than in situ success in an aquarium but that has yet to happen.

Thanks for the update.
 

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