Arrow Crab with a trap door.

[njbeacher]

I have had an Arrow Crab for a few months now. In the last day or so, he/she has developed what looks like a trap door. He/she is still fine as far as I can tell. Eating, walking and doing whatever Arrow Crabs do when they walk around the tank. Has anyone ever seen this before? It is a female and that is where she would keep her eggs?
Thanks.

 

[nwdyr]

don't know but I am also curious to find out what it is!!

 

[reefforbrains]

I always thought the flap was a male Crab, and thats where he kept his.........
Females no flap.

 

[njbeacher]

I will say this about it...It is a little disturbing. Doesn't it feel a little bit drafty down there? It's like looking at someone with a hinged skull, and thier brain is visible.

 

[reefforbrains]

Just because we think get accused of thinking with it doesnt make it a brain.
of course its still to be determined on what it exactly is on Arrow crabs. I only truley know sexing on the larger crabs. The larger ones are easy and distinct. I would assume it is similar but certainly not concrete.

 

[njbeacher]

I guess then it is equally disturbing to think he is just happy to see me?
<shudder>

 

[keri]

heh... it gives it quite a Suprised look lol
Could be due to something to do with shedding, maybe a bad shed? Or maybe it's about to shed? that flap is usually held tight up against the body, nomatter how attractive you are she likely isn't holding it open for you Make sure there is no fungus or anything growing in there. (or eggs! eggs would be better than fungus)

 

[crabsrkewl]

I'm pretty sure every species of crab excluding hermits have that or at least the one's I've seen at the beach

 

[ophiura]

That is normal, it is a modification of the abdomen. In lobsters, the abdomen is the "tail" and highly functional but in true crabs it is modified and reduced. It is held up under the body.
Yes, it is where the eggs would be kept, and females have a broad abdomen (males have a very narrow abdomen).

 

[smokingreefer]

Originally Posted by ophiura
http:///forum/post/2638975
That is normal, it is a modification of the abdomen. In lobsters, the abdomen is the "tail" and highly functional but in true crabs it is modified and reduced. It is held up under the body.
Yes, it is where the eggs would be kept, and females have a broad abdomen (males have a very narrow abdomen).
Mine did the same thing when I had it so don't be alarmed.

 

[valgae]

we go "crabbing" down here on the gulf coast. the females have a round flap males have a rocket. we always have to throw the females back.

 

[weirdcrab]

So...my arrow crab regularly eats out of this "trap door" and it freaks me out! So is she eating her eggs?