SIr, i am working on two crabs, one is identified as Paratelphusa masoniana while other havenot identified yet. yeah, one thing is true that i am working on adult crabs, so may be as per your view it will take long time but how much? Its 4 months over now. Secondly sir, i donont know one of the plausible reason that a female having crablets in its abdomen showed cannibalistic attitude towards its youngone, even she was provided with quality food. why its so?

The females do such things under stress conditions. And they molt ONLY if the conditions are good and they feel comfortable.

Does Paratelphusa have a terminal molt? If so, they won't molt after reaching adulthood. As others mention, adults in some species do not molt often. Work by Adiyodi indicates that one species of Paratelphusa molts after their 3d ovarian cycle, which might indicate but once per year or a terminal molt depending on the species: http://www.jstor.org/stable/30155451, and http://www.tandfonline.com/doi/abs/10.1080/01651269.1981.10553379

http://link.springer.com/article/10.1007/BF00016859#page-1

You might try a literature search on these references.

As Oleg points out, cannibalism is common in crabs, you need to separate the larvae from the female. The larvae may cannibalize each other, too, so you need to provide ample space and food if you're trying to rear them. Zmora's work with Callinectes gives some details for rearing a portunid.

http://www.sciencedirect.com/science/article/pii/S0044848604006544

There are likely some references for breeding Eriocheir or Paratelphusa, too.

Tnx Jeffrey Sir

..despite the fact that they are freshwater crabs, are they always in freshwater or they migrate to estuarine systems to reproduce?

Are you sure the water quality under which you're rearing them are specific for the species, did you confirm the variables in the wild and apply them to your rearing system?

..as already suggested separate the young from the adults after they emerge,. Most animals not only crabs are cannibalistic on their young when in captivity.

Respected Azubuike, i have work in the wild and recorded the various parameters (physico-chemical) that are suitable to them and yeah these are exclusively freshwater crabs, as there donot have any source of water other than freshwater... thanks for the reply..

can you suggest some experiment that i can perform on crabs under lab conditions?

...as regards experiments i'll suggest growth experiments using different kinds of feeds to see which promotes growth and maturity faster. The preferable life-stage to use would be the juveniles, because they have a greater need to grow than the adults.

..as i asked earlier how much of their biology do you know? do they reproduce all year round or seasonally, in which case specific environmental variables may be required for their growth, development and reproduction.

Many records of failure in rearing species in captivity has been largely attributed to limited knowledge of their reproductive biology, cycle and cues.

They are seasonal breeder and breed twice in a year, june-july and december-january...

From your analysis of water quality is there any similarity in water quality parameters between these two periods? if yes, what are those parameters?

High oxygen and absence of carbonates

High oxygen suggests that your rearing set-up will require sufficient oxygen supply, while carbonates suggests you check the water hardness and presence of carbonates that may make your set-up unsuitable for rearing the species.

My experience reveals that if you rear them in the lab in adult condition, it would be difficult to see them molting. However, if it is in the molting season, and if the crab has already shown signs of premolt initiation (this could found out from microscopic observstion), then the molting would furthered in the lab condition, which in turn would be a good opportunity to observe them molting and characterize the molting stages. If you have more questions, I would be glad to answer.

Anilkumar Gopinathan

Professor

School of Biosciences and Technology

VIT University, Vellore, Tamil Nadu, India

Cell phone: 9952187178

My experience reveals that if you rear them in the lab in adult condition, it would be difficult to see them molting. However, if it is in the molting season, and if the crab has already shown signs of premolt initiation (this could be found out from microscopic observation), then the molting would be furthered in the lab condition, which in turn would be a good opportunity to observe them molting and characterize the molting stages. If you have more questions, I would be glad to answer.

Anilkumar Gopinathan

Professor

School of Biosciences and Technology

VIT University, Vellore, Tamil Nadu, India

Cell phone: 9952187178

[email protected]

Depends on molting period and age of reared species. If you caught recently molted specimens (after molting period) and if they are adults, it is possible, that they molt only once or twice per year. So you can wait some weeks or months. It is very usual pattern - younger decapods molting more offten, while adult large ones reduce their growth (i.e. molting).

From factors (environmental) inhibiting molting process it would be low temperature or low pH value.

Milos

You can observe molting stages by examining third maxillae of mastigobranchi or you can observe the carapace sliding at the back of the crab.