Early Busting signs?

[MDblue1984]

Ok.. As some of you are aware, I have a little 4" blue crab as a pet. Had it since it was 2 and 3/8" and it has molted twice.. (checked with VIMS and they said it's legal to own a blue as a pet under 5")

The premolt signs on juvies seem to be different than mature adults..

One thing I have noticed, is instead of red signs, they seem to be black signs instead. Dunno why that is, just seems to hold true.

His swimmer fin goes black around the edges and bottom usually a week out from molting (observed from 2 prior molts) **in picture**

now the one thing I am curious about is that I am pretty sure he is REALLY close to busting.

It looks to me (also in the picture) that before he seperates his carapace, do they also seperate the chitin around the swimmer fin as well?

In the picture, it looks as if the outer shell is broken around the ligament and the newer, soft shell is protruding a bit. I can't get him to get at a good angle to take another picture, but it looks like his old shell has cracked about 3/4 of the way around his swimming legs. The "unbroken" part of his hard shell looks to be on his underside where all the other leg joints meet. Reasoning suggests they do this due to the fact that they need more room to help "jimmy" (pardon the pun) their swimmers out of the old shell.

Would I be correct in assuming this is a normal trait in molting blues? Or am I so incredibly impatient for him to molt that I am, in fact, seeing things?

[jack1747]

The first crack is under the points on the carapace...

[Mikie]

Just looks like the normal membrane at the joint to me, from the picture. I don't see any "sign" at all on the swim fin. I've had plenty of peelers smaller then 4" and they all display the normal signs prior to molting. Maybe just not showing up on the picture, be sure to post if it sloughs any time soon.

The top shell has to separate and lift across the rear, from the crab swelling inside, that is what provides the room for the crab to work the swimmer fins out, and then back the rest of the way out of the shell. As a side note, just about all of the ones that don't make it - the swimmer fins get hung up and don't come out, which doesn't allow the crab to back out.

[jack1747]

I agree.  Kept 100s of crabs in aquariums.  Started back in the 50's using pickle jars.  They all signed the same. 

[MDblue1984]

Ive had this one molt on me twice, and ive been there for both. Very interesting to watch.. it just looked like the joint was separated from the shell.

I have yet to see a red sign out of this guy.. so far, the black colors on the swimmer you see in the picture, shows up bout a week or two prior to molt. it starts on the tip of the paddle, very faint, grows out a bit, then lines the entire swimmer paddle like red sign adults. anyone know what that may be? led me to believe it was a pre-molt sign in juveniles.

Just looks like the normal membrane at the joint to me, from the picture. I don't see any "sign" at all on the swim fin. I've had plenty of peelers smaller then 4" and they all display the normal signs prior to molting. Maybe just not showing up on the picture, be sure to post if it sloughs any time soon.

The top shell has to separate and lift across the rear, from the crab swelling inside, that is what provides the room for the crab to work the swimmer fins out, and then back the rest of the way out of the shell. As a side note, just about all of the ones that don't make it - the swimmer fins get hung up and don't come out, which doesn't allow the crab to back out.

[MDblue1984]

PLEASE TAKE NOTE: that I am in no way trying to say I'm right in any of this. Just trying to wrap my head around this strange, delicious creature living in my fish tank.

[Mikie]

Ive had this one molt on me twice, and ive been there for both. Very interesting to watch.. it just looked like the joint was separated from the shell.

I have yet to see a red sign out of this guy.. so far, the black colors on the swimmer you see in the picture, shows up bout a week or two prior to molt. it starts on the tip of the paddle, very faint, grows out a bit, then lines the entire swimmer paddle like red sign adults. anyone know what that may be? led me to believe it was a pre-molt sign in juveniles.

You might be looking at the wrong spot on the swimmer fin. You don't look at the "paddle", you look at the next section back. Click on the crab at the bottom of the page, go in the science section and look under molting. There are some excellent pics in there of where and what to look for.

[jack1747]

Try to get someone that sheds crab to show you the signs. Sometimes it's almost impossible to learn it on your own.

A few seasons ago I was working on a peeler boat and was having a terrible time signing the peelers.  Until the Captain said, "are they polarized sunglasses?" 

I guess your not wearing sunglasses while looking at the aquarium tho...