Hi Ardavan,

Interesting question - are you sure sex reversal can occur in crayfish / crab?  I had assumed it was fixed genetically, in part because of the occasional presence of hermaphrodite individuals that are male on one side and female on the other.  Similar to occasional animals with different pigmentation on each half. Cheers, caleb.

Hi Caleb. Yes it is possible in most crustaceans species by manipulation androgenic gland (AG) or androgenic gland hormone (AGH). If we block AG peptides or remove AG from body we can produce female animals. Also it can be affect by environmental situations as you said (occasional presence of male or female) or by temperature and ...

Amir Sagi published to many articles about this matter: http://www.bgu.ac.il/~sagia

thanks dear Koushik. 

Do you know any reference about the time of start sex differentiation in crayfish? or maybe in crab? 

Dear Ardavan

First crab Instar is next to megalopa stage in crab larval stages and physical sex determination is at First crab Instar stage. Whatever manipulation by using hormone you do before attaining First crab Instar stage only. Applying intended method at larval stage will result in sex reversal/production of mono sex of large population. Please follow the reference given here.

Baghel D.S.,Lakara W.S., Rao G.P.S., 2004. Altered sex ratio in giant fresh water prawn, Macrobrachium rosenbergii (de Man) using hormone bioencapsulated live Artemia feed. Aquaculture Research, 35, 943-947.

All the best for your innovative idea.

I think normal sex reversal is rare in true crabs (Brachyura). There are some reports in mole crabs, e.g., http://www.biolbull.org/content/160/1/161.short. It does occur in crabs as a result of feminization from rhizocephalan barnacles and perhaps a few other parasitic castrators. Normal sex reversal is much more common in shrimp and there are several papers in the literature on this. I think in crayfish, it's done experimentally as Ardavan Farhadi has indicated, by removal of the androgenic gland, but does not occur as a normal developmental process.