Mirelurk

Mirelurk is a term referring to a range of mutated creatures.

Background
Ada mentions the mirelurk is an irradiated, "hyper-evolved the horseshoe crab" that functions in a caste-like system. Moira Brown classified them as Scylla Serrata Horrendus and questioned if they had evolved from crabs or some sort of brine shrimp. John Hancock states that mirelurks were much smaller before the bombs dropped.

Mirelurks nesting below inhabited decks are considered a nuisance for inhabitants of Rivet City, regularly exterminated by the city's security team. They lay eggs in small clutches and grow quickly, used as food and traded throughout the wasteland. Mirelurks are sensitive towards high pitched noises, such as those occurring in Vault 92 and on Spectacle Island.

Crab mirelurk


 Mirelurks are heavily armored and resistant to most forms of damage, but their faces are vulnerable. Other animals tend to avoid mirelurks, perhaps instinctively realizing the danger posed by the shell. 

Mirelurk king


Mirelurk kings have distinct adaptations to their water-rich environment, with pronounced webbed extremities and numerous fins all over its body. They also have the ability to cloak themselves in order to ambush unsuspecting prey.

Behind the scenes



 * Porter Gage refers to mirelurks as "mudcrabs" when talking to him. 