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Cuttlefish egg bubble?


Blue Ring
Aug 29, 2014
After lurking for a while I finally pulled the trigger and setup a small cuttlefish tank. After cycling and running the tank for a few months with a pair of chromis and some assorted macro I ordered some bandanesis eggs from bluezoo. The eggs arrived 2 weeks ago and appeared to have no issues and after acclimating I added them to breeder net.

So far none have hatched but this morning when I woke up I noticed a single egg appears to have a relatively large clear bubble growing out of it. It doesn't appear to have any holes in the egg or bubble from anything hatching and I haven't seen movement in the bubble while the main egg remains black. Does anyone have any idea what is happening or what caused the bubble? Is this normal? Google found a few vague references but nothing really detailed. I've attached a pic but the photo is bad through the breeder net mesh.
I've noticed it doesn't seem to be active and just sits in the corner of the breeder net all day. Is that normal? I added a few live mysis of various sizes and they don't seem to illicit any response even when they walk over it exploring themselves. It's changed position once since it hatched. Aren't they usually more active and inquisitive?
Also this morning I noticed the egg sack detached and is floating around. Will they circle back and eat it or should I remove it?
Usually we see bubbles like that when the egg casing has been breached from some kind of mechanical damage, possibly from the shipment. As the egg swells in later development, it pushes out the hole. These eggs tend to hatch prematurely, which could be why your little one isn't doing so well. I hope the others are still looking ok!
The fact that it had not fully consumed the yolk sack agrees with @Tentagal 's suggestion that this one likely hatched prematurely. Unfortunately, few survive if they have not fully consumed the yolk sack before hatching but keep offering live mysis and be sure there is plenty of dark time as new hatched often feed only at night. If you don't have it in the breeder net now, you might also add some chaeto to serve as both a hiding and hunting environment.
The one that had the bubble actually wasn't the egg that hatched. The bubble seems to have grown more but hasn't hatched as of this morning. This morning the hatchling appears to have developed color where yesterday it was pure white. I currently have some ulva in the breeder net for coverage. There are a few mysis in the breeder net and keeping lights off while I'm at work so I guess time will tell.
You still might try a little chaeto since the ulva is less open. Both should attract the mysis but I am not sure if the cuttle will be encouraged to hunt there.
Yeah it's mostly ulva but kinda clump of macro as well with some coulerpa etc. I noticed today it is more of a muted beige instead of the solid white it was originally so taking that as a decent developmental sign. When I got home tonight I could at least visibly see it's eyes darting around watching stuff unlike any time I've viewed it prior.

Today a few other eggs are starting to bubble and a few are starting to just stretch and become clear. Saturday will be 3 weeks since they arrived so I'm guessing any day will have more hatching.
If you go through a few of the journals you will notice that it is not unusual to be concerned about new hatchlings not eating or at least not being seen to eat. The existence of a yolk sac at hatching is a bigger concern but the best we have seen is to continue to introduce new food regularly (twice or three times a day seems to give the best result).

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