Commercial Fisheries News - July 1999
For lobsters, molting is a continuous process. Lobsters are always either preparing for, recovering from, or actually molting - except for adults who take a bit of time off for reproduction. Incidentally, adult females take more "time off" between molts because they carry the eggs for 9-11 months!
Great preparations take place when a lobster gets ready to shed. First, it starts to break down its old shell to soften itself up at the joints and around the edges. This makes it possible to squeeze out of the old shell later on. The lobster recycles the hard stuff (especially calcium) by dissolving and taking it up in the hemolymph (basically, lobster blood) and by storing it as stone-like "gastroliths" in the stomach.
During premolt (the days to weeks before shedding), the lobster also grows back missing parts. You can see how close to shedding a lobster is by looking at the condition and color of the "limb buds" - i.e., the stubs growing back where a lobster has lost some part of itself. Limb buds start out clear and turn pale blue, pink, and then bright red. When a lobster is within a day or two of shedding, the limb buds turn dark blood red in color. You may also be able to recognize a premolt lobster by its dark body and the presence of a deep blue line along the edge of the carapace. That line is actually the edge of the fully formed new shell underneath the old shell.
Premolt lobsters need special care because while they look and feel hardshelled on the surface, they are weak and the delicate limb buds break off easily.
Next time, I'll talk about how the lobster gets out of its shell and how to handle a freshly molted lobster.