Dear Blue Lobster:
My yabby recently molted (is that the correct terminology?) And looked really good with its new and enlarged body but then last night I noticed that both arms and most of his legs were missing! He has a partner living with him and they get along fine. Would the loss of his arms and legs be the result of an attack? He is much bigger than his partner and now he has only one back leg on his left side and two back legs on his right and he seems to be struggling to move and around and eat.. Is there anything I can do to help it and how long til the legs grow back?
Thank you for your time.
Dear Gentle Sir:
Indeed, molting is the proper terminology for what scientists call ecdysis, the process by which an arthropod sheds its exoskeleton in order to grow. It is a dangerous process for your cray and can often result in dropped limbs, depression, and even suffocation.
In your yabby's case of missing legs, however, it sounds like domestic abuse is at play.
Domestic abuse in pets — especially crustaceans — is a little-heard-of and oft-ignored issue. It is thought that among arthropods alone, negelct and abuse account for 90% of injuries and death. Most forms of abuse are passive; that is, the owner doesn't realize they are mistreating their animals. In some cases, like yours, the abuse is carried out by fellow crustaceans.
In domestic relationships, molting is a time when tensions mount due to the preparation for the molt and subsequent recovery. When the molting cray is naked and vulnerable, the other cray will often tear limbs off or otherwise physically abuse its partner in the hours before a new exoskeleton forms.
In the future when one of your crays is about to molt, isolate it until its new exoskeleton has set. You can do this by means of a fry box, a separate aquarium, or a tank divider. You can tell the cray will molt when it begins refusing food and remains idle most of the time. Either that, or it's about to die.
In future molts, your cray's limbs should regrow, though they may be undersized. After a few more molts they will funtion normally and your cray will be healthy. In the meantime, with its reduced mobility, it might be a good idea to isolate the cray or feed it with chopsticks directly to its mouth.
Good luck on its next molt!