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This is an overview article which contains background information and cross-game comparisons. For game-specific information and stats, see the articles linked on the right.
Gameplay articles
Fallout 3Mirelurk
Mirelurk hunter
Mirelurk king
Point LookoutSwamplurk
Swamplurk queen
Fallout 4Mirelurk hatchling
Mirelurk spawn
Softshell mirelurk
Mirelurk razorclaw
Mirelurk killclaw
Glowing mirelurk
Mirelurk queen
Mirelurk hunter
Mirelurk king
Far HarborBloodrage mirelurk
Nuka-WorldNukalurk hunter
Nukalurk spawn
Nukalurk queen
Nukalurk king
Fallout 76Mirelurk spawn
Mirelurk hunter
Mirelurk king
Mirelurk queen
Nuclear WinterPrime mirelurk queen
Venomous mirelurk
Steelshell mirelurk
Hardshell mirelurk
Mirelurk vorpalclaw
Deadly mirelurk
Mirelurk hunter
Mirelurk king

Mirelurk is a commonly used term referring to a range of mutated crustacean and turtle species endemic to the Eastern Seaboard, particularly areas belonging to the Columbia and New England Commonwealths.

A similar term, lakelurk, is used to refer to mutated turtles in the Colorado watershed in the Mojave Wasteland.


Mirelurks have the dubious distinction of being one of the first radioactive mutants to emerge into the world, as a result of widespread radioactive pollution of the environment by United States megacorporations such as Poseidon Energy or General Atomics. Environmental organizations such as Nahant Oceanological Society, dedicated to saving the oceans, attempted a variety of last-ditch efforts to raise awareness of the problem and encourage radical action to curtail environmental destruction at the hands of reckless corporations.[1] However, their efforts were in vain. Ignored by authorities, to the point where they refused to even take their phone calls (as was the case with the Boston Port Authority), they attempted to garner attention by reporting the situation to the Galaxy News Network. The media ignored their reports as well, except for running a story about the upcoming shellfish season and how great it was going to be. Of course, it neglected to mention that the average increase in mass on the order of 14% in crabs and 12% in lobsters meant that the available food supply would run out quickly, leading to colony collapse and localized extinction.[2]

Although the Great War put an end to corporate pollution, it was replaced by overwhelming amounts of nuclear fallout instead. In the ensuing melting pot of mutations, the modern mirelurks emerged. Attempts to classify the resulting creatures have proven difficult. The crab mirelurk, for example, contains multiple phylum markers from two distinct and unrelated species: The Atlantic horseshoe crab (Limulus polyphemus) and the Atlantic blue crab (Callinectes sapidus). As such, it would be necessary to catalog it simultaneously as belonging to the Crustacea and the Chelicerate phylums, with the simultaneous classification of two distinct classes (Merostomata and Malacostraca). As such, wasteland scholars generally assign it its own classification: Scylla serrata horrendus.[3][4] Mirelurks are also known to have a pronounced sensitivity to white noise, as seen in Vault 92 and on Spectacle Island.

Although mirelurks tend to inhabit polluted rivers, coastal waters, and sewers, their meat is considered a delicacy among wastelanders. Mirelurk hunters and herders can count on a steady demand for their meat and make a high profit selling it to wasteland traders.[5] However, the size of the meat market means competition is stiff and suppliers can be targeted by rivals attempting to knock them out of the market (sometimes literally).[6] They also grow remarkably fast, requiring just a few weeks for them to reach maturity. If corraled and domesticated, mirelurks can be a flexible supply of food. The Free States did, in fact, entertain such an option.[7]

Mirelurks can also be a blight on permanent settlements, as is the case with Rivet City. Mirelurks nesting below inhabited decks are a continued nuisance for denizens of the city, despite regular extermination operations by the city's security team.[8] Infestations are made even worse by the fact that mirelurks have adapted to lay their eggs in multiple small nests throughout shallow water (unlike pre-War crustaceans that adhered their eggs to their body), likely because they grow larger relative to the parent and have developed a hard calcified shell; if disturbed, the larval mirelurks within exhibit incredible precocious behavior and are ready to attack if need be.[9]


Crab mirelurkEdit

Gameplay articles: Fallout 3, Fallout 4, Fallout 76

One of the most common variants of the mirelurk, Scylla serrata horrendus is the result of mixing between Chesapeake Bay horseshoe and blue crabs. Regional variations exist: for example, crab mirelurks in the Capital Wasteland tend to be bipedal and slimmer, while those in the Commonwealth and Appalachia are quadrupedal and rounder.[10]

Their most noticeable feature is the large, chitinous shell that provides excellent resistance to firearms, melee weapons, and even ray guns. Soft body parts, such as their faces and sections of their abdomen, are much less resistant.[3][11][12] Of course, that only applies to adult mirelurks. The shell's chitin takes time to harden and young mirelurks are quite vulnerable at that stage of their life.[13]

An interesting feature of crab mirelurks is that they instinctively know how to protect themselves with their shell. When faced with prey that can attack them at long range, a crab mirelurk will lower its head to cover its body with the chitinous shell, greatly increasing its ability to survive.[14] Other animals tend to avoid mirelurks, perhaps instinctively realizing the danger posed by the shell.[7]

When hunting, mirelurks rely on their extraordinary sense of smell, with their poor eyesight a secondary aid. They catch their prey with their primary large claws. Once immobilized, the prey is then stripped down and consumed with the claws on their abdomen, capable of stripping animals down to the bone within minutes.[7]

Lobster mirelurkEdit

FO4 Mirelurk hunter transparent
Gameplay articles: Fallout 4, Fallout 76

The lobster mirelurk is a unique mutation found in New England environs, called mirelurk hunter by its denizens. The most characteristic elements of this kind of mirelurk are the oversized claws and its head, housing the eyes and antennae, its primary sensor organs.[15] Although they lack the protection of their crab cousins, lobster mirelurks make up for it with their more powerful melee strikes and the ability to spit corrosive acid at targets.[9]

Turtle mirelurkEdit

Gameplay articles: Fallout 4, Fallout 76

The third of the major mirelurk types, the kings are heavily mutated snapping turtles.[16] Standing upright on two feet, they are the most human-like of the mirelurks, especially in terms of behavior. They have a symbiotic relationship with the other mirelurk types and commonly employ ranged attacks. Early concepts had the idea for their opposable claws to allow them to employ weapons such as machine guns, though this was not implemented in the final design.[17]

Though it appears human in shape, the mirelurk king evolved, forced by the pollution and radiation. Its upper and lower fins have developed joints and claws capable of flexion. Although there is no evolutionary link between the mirelurk kings and the mirelurks themselves, the species have formed a symbiotic bond of sorts. The kings' superior intelligence allows them to dominate and perhaps control their less intelligent mirelurk peers, which in turn can expand their territory more efficiently under their control.[18]

Common kingEdit

Mirelurk king
Gameplay article: Fallout 3

The mirelurk king lacks the characteristic shell of other mirelurk variants but makes up for it with their thick, leathery skin, powerful arms and legs, and the ability to shriek at their attackers. This sonic attack is particularly dangerous against unaware or weakened targets.

Commonwealth mirelurk kings have distinct adaptations to its water-rich environment, with pronounced webbed extremities and numerous fins all over its body. Their coloration is also red, rather than the typical blue. They also have the ability to cloak themselves in order to ambush unsuspecting prey.[19]

Swamplurk queenEdit

Swamplurk queen
Gameplay article: Point Lookout

A regional variation of the mirelurk king, the queen is found in Point Lookout. The environment of the swamps resulted in adaptations such as a coat of algae covering its skin, providing a degree of natural camouflage, and the ability to spit corrosive, radioactive acid at its prey.


Gameplay article: Fallout: New Vegas

A unique type of turtle mirelurk, endemic to Lake Mead and the Colorado River. They have a distinct, green coloration and the usual sonic attack.

Behind the scenesEdit

The mirelurks got a bit of a reboot visually, as well as significant expansion on the variants with the addition of the hunter and the queen. This was simply a case of wanting to try something a bit more animalistic and to move away from the guy-in-a-suit vibe of the original.The Art of Fallout 4
Though it appears human in shape, the Mirelurk King evolved in non-sapien ways; namely, its upper and lower fins have developed joints and claws capable of flexion. Similarly, there is no evolutionary link between the Mirelurk Kings and the Mirelurks themselves; the story I told myself while building this Lovecraftian monstrosity was that his kind had evolved in ways that allowed them to dominate and perhaps control their less intelligent Mirelurk peers.

To reinforce this idea, I doubled down on the “Kingly” imagery by sculpting a hard-shelled crown (which was in the concept art to begin with) a la Dunkleosteus, as well as dressing him in long, sweeping red “gill robes,” like the ancient western kings (which was not in the concept art). I built him anticipating that he’d walk upright, proudly, with this chest out - like the Fallout 3 variety. Alas, the animator chose a more froggish route.

The model itself is 9.1K triangles, the textures 2048. It was created for Fallout 4.
Jonah Lobe


  1. Nahant Oceanological Society terminal entries; research terminal, Goals
  2. Nahant Oceanological Society terminal entries; research terminal, Lobster growth
  3. 3.0 3.1 Enclave field research terminal entries, Enclave field research terminal, Field Entry: "Mirelurk"
  4. The Lone Wanderer: "They descended from local crabs. I'd call them "Scylla Serrata Horrendus.""
    Moira Brown: "That's very scientific of you! Personally, I wasn't sure if they were crabs or if they came from some sort of brine shrimp, perhaps. Some of these observations about their armor and camouflage gave me an idea for reinforced, neutral-colored headgear. Here, consider it thanks for not interfering with them. Oh, speaking of which, take these. So you can continue to avoid them in the future."
    (Moira Brown's dialogue)
  5. Note for Ted
  6. Merc's orders
  7. 7.0 7.1 7.2 Mirelurk research
  8. Rivet City terminal entries; Bannon's terminal, Council Meeting Minutes
  9. 9.0 9.1 Behavior in Fallout 4.
  10. Morphological differences between the two crab mirelurks seen in Fallout 3 and the ones in Fallout 4 and Fallout 76.
  11. Fallout 4 loading screens: "Most Mirelurks are heavily armored and resistant to most forms of damage, but their faces are vulnerable."
  12. Tenpenny Tower terminal entries; exploration database, Mirelurks
  13. Softshell mirelurks
  14. Behavior of mirelurks in Fallout 4 and Fallout 76.
  15. The Art of Fallout 4 p. 196: "We really needed to include lobsters, given the location."
  16. The Art of Fallout 3 p. 42: "Snapping turtle variation"
  17. Fallout 3 concept art by Adam Adamowicz: "OPPOSABLE CLAW for gripping primitive weapon... like machine gun"
  18. Jonah Lobe: "Though it appears human in shape, the Mirelurk King evolved in non-sapien ways; namely, its upper and lower fins have developed joints and claws capable of flexion. Similarly, there is no evolutionary link between the Mirelurk Kings and the Mirelurks themselves; the story I told myself while building this Lovecraftian monstrosity was that his kind had evolved in ways that allowed them to dominate and perhaps control their less intelligent Mirelurk peers."
  19. Fallout 4 loading screens: "Some creatures, like the Mirelurk King, Chameleon Deathclaw and Sentry Bot, can utilize stealth to turn themselves almost invisible and ambush unwary prey."
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