Have you ever seen a lobster with an eroded looking shell, with lesions or spots on its back? Lobsters have been known to get shell disease, an epizootic disease caused by bacteria that could be affected by their environment. Between 1998 and 2004, shell disease has been observed in lobsters all the way up to mid-coast Maine. Shell disease is more prevalent in southern waters and corresponds to warmer water changes. (Journal of Crustacean Biology, n.d.)
The lesions start out small but once they become visible other organisms like bacteria, protozoans, and nematodes can be found living in the infected area. It appears that the disease increases as the lobsters’ vulnerability to it increases. Lobster shells play an important role in protecting them from diseases. Their shells are made up of calcium, phosphate and magnesium. The chemical reactions that occur when these minerals dissolve in the surrounding seawater create higher pH levels and that creates a barrier between the lobster and the seawater. Ever wonder why a lobster may feel slippery? That is the protective barrier! (https://www.fisheries.noaa.gov/science-blog/lobster-shell-disease).
Shell disease can cause mortality in lobsters which can attribute major economic losses and has not been known to be a threat to humans as it has not been linked to pollution. But it is possible for these lobsters to recover from shell disease. As noted in section 1.4 Molting lobster may be able to shed the disease with their shell. But if the infection reaches the epidermal cell layer it can enter their blood stream and ultimately kill them.
Mutations can vary in lobsters in severity and type. When you see a blue, yellow, red, or even white lobster, that is a genetic mutation causing their color to be abnormal. Some lobsters have been documented with numerous claws on one arm, malformed claws, and even dual sex organs. Although lobsters with mutations like these are safe to consume, they are rare wonders and are often given to aquariums for preservation.