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This is a lore summary, presenting intradiegetic or in-universe information about the subject. For game characteristics and similar data, consult the table on the right.
Game-specific articles
Fallout 3Mirelurk
Mirelurk hunter
Mirelurk king
Fallout 3: PLSwamplurk
Swamplurk queen
FO: New VegasLakelurk
Fallout 4Softshell mirelurk
Mirelurk razorclaw
Mirelurk killclaw
Glowing mirelurk
Mirelurk hunter
Glowing mirelurk hunter
Albino mirelurk hunter
Mirelurk king
Mirelurk deep king
Glowing mirelurk king
Mirelurk spawn
Mirelurk hatchling
Far Harbor
Bloodrage mirelurk
Nukalurk hunter
Nukalurk king
Nukalurk spawn
Nukalurk queen
Fallout 76Softshell mirelurk
Mirelurk razorclaw
Mirelurk killclaw
Glowing mirelurk
Bloodrage mirelurk
Strangler mirelurk
Mirelurk hunter
Albino mirelurk hunter
Glowing mirelurk hunter
Mirelurk king
Mirelurk deep king
Glowing mirelurk king
Mirelurk queen
Glowing mirelurk queen
Glowing mirelurk spawn
Mirelurk spawn
Mirelurk hatchling
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Gametitle-FO3.pngGametitle-FO3 PL.pngGametitle-FNV.pngGametitle-FO4.pngGametitle-fo4fh.pngGametitle-fo4nw.pngGametitle-F76.png

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 catalogue it simultaneously as belonging to the Crustacea and the Chelicerate phylums, with simultaneous classification a two distinct classes (Merostomata and Malacostrata). As such, wasteland scholars generally assign it its own classification: Scylla serrata horrendus.[3][4]

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 mirelurk (Regular)

Gameplay articles:

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 - migrating from Chesapeake Bay[10] - are quadrupedal and rounder.[11]

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][12][13] 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.[14]

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 range, a crab mirelurk will lower its head to cover its body with the chitinous shell, greatly increasing its ability to survive.[15] Other animals tend to avoid mirelurks, perhaps instinctively realizing the danger posed by the shell.[16]

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.[16]

Lobster mirelurk (Hunter)

Gameplay articles:

The lobster mirelurk is an 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.[17] 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] Its prey is usually consumed whole and digested in the stomach, using acids and teeth embedded in the lining.[18]

Turtle mirelurk (King)


The third of the major mirelurk types, the kings are heavily mutated snapping turtles. 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 which the other variants lack.[19] Their hands allow them to employ simple tools.[20] They also constantly exude slime to prevent their skin from drying.[21]

Though it appears human in shape, the Mirelurk King evolved in non-sapien ways, 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.[22]

Common king

Mirelurk king.png
Gameplay articles:

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.[23]

Swamplurk queen

Swamplurk queen.png
Gameplay article:

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:

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 scenes

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 terminals: Research Terminal, Goals: "Here at the Nahant Oceanological Society we strive to save our oceans by researching the longterm effects of radioactive exposure on aquatic life and working with the community to raise public awareness. We believe that companies such as Poseidon and General Atomics have gone unchecked too long and that radical action is neccessary to protect our world from a horrific future."
  2. Nahant Oceanological Society terminals: Research Terminal, Lobster growth: "This is insane. An increase in average mass by 14% in crabs and 12% in lobsters is not something to be celebrated! If this trend continues, the additional food necessary to sustain the shellfish population could lead to colony collapse! I've tried again to bring our findings about the growth and mutations to the press and those assholes at GNN just took our findings and spun them into a story about how great shellfish season is going to be."
  3. 3.0 3.1 Enclave Field Research Terminal, Field Entry: "Mirelurk": "Kingdom: Animalia
    Phylum: Arthropoda
    Subphylum: Crustacea/Chelicerata???
    Class: Merostomata / Malacostraca / ???
    Order: ???
    Family: ???
    Genus: ???
    After going to enormous lengths to procure DNA samples of hypothesized forebears, we cannot explain why ancestry evidence is present from two vastly different creatures; the Limulus polyphemus (horseshoe crab) and the Callinectes sapidus (blue crab). It's obvious that a mutation occurred, giving this creature bipedal movement and massive growth, but I cannot explain the presence of multiple subphylum markers in DNA/RNA. Given their mystifying origins, I have decided the species deserves its own classification, and have thus dubbed them "Scylla Serrata Horrendus." They can often be found in sewers and caves and should be considered hostile and very dangerous, as their chitnous shell provides excellent resistance to both firearms and hand-held weapons. They are disgusting creatures, and I cannot fathom their popularity as a food source among the citizens of the Wasteland."
  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: "Ted,
    The Mirelurks busted out of the storage area and have been raisin' hell through the whole facility. Price says the bastards get smarter every day. He says I'm paranoid, but I think somebody might be sabotaging things around here. We've taken on so much extra help, I don't know who I can trust around here anymore. Things don't look too good.
    I don't think I'll be walking out of here, and I figure you should be the one to get our stash. I managed to get it hidden pretty well in case something like this happened.
    I don't want any of these damn fools tripping over it, so I threw a couple of curves in, but it's nothing you can't handle. Start with my terminal -- just log in and follow the instructions. And if for some reason you've forgotten the password, you might want to sit down and have a think with a Nuka-Cola, if you catch my drift.
    If this damn meat weren't in such high demand, I'd have pulled out of this racket before the word go. I got too greedy, Ted."
  6. Merc's orders: "By now, your handler's given you the location of the job and your basic orders. Here are the details.
    Traders have been making a killing with Mirelurk meat, and we've been losing business because of it. One of our people got involved with a caravan supplier, and we finally know where it's all been coming from.
    The meat's mostly coming from one group holed up along the river smack in the middle of the ruins. There's a huge old facility under some war memorial where they've herded up a nest of Mirelurks and have been breeding and butchering them. They've been in business for months and are sure to be sitting on a pile of caps. Take what you can carry -- we just want them out of the meat market. The rest is up to you.
    This isn't the biggest job, but pull it off clean and there's plenty more work for a man with your skills. Get back to your handler as soon as the job is done and we'll be in touch."
  7. Mirelurk research
  8. Rivet City terminals. Council Meeting Minutes: "In attendance:
    Science Rep. - Dr. Madison Li
    Civilian Rep. - Bannon
    Security Rep. - Harkness
    * Bridge repair continues to be a drain on funds. Permanent bridge considered, but dismissed as too risky, in case of attack.
    * "Bridge Tax" for non-residents proposed by Bannon. Vote fails.
    * Hydroponics and city health continues well, thanks to the efforts of Dr. Li and her scientific team. However, system breakdowns are commonplace, requiring much maintenance.
    * Li proposed recruiting other scientific minds from Tenpenny Tower or Underworld. Vote fails.
    * Attempts to clear out the Mirelurk infestation in down-below continue as usual. Harkness and team is able to contain them and occasionally wipe them out, but they continue to nest in the area, posing a theoretical risk if they ever turn aggressive towards higher decks.
    * Bannon suggests closing off lower deck fore. Vote fails.
    * Funds and ammunition allocation for a Mirelurk cleaning operation proposed by Harkness. Vote passes.
    * Dr. Li leaves early to oversee hydroponics testing.
    * Meeting adjourned."
  9. 9.0 9.1 Behavior in Fallout 4.
  10. Quercus: " Oh, lovely! The classic mirelurk, migrated all the way from the Chesapeake Bay. Your friends have taken up quite a residence here, haven't they?"
  11. Morphological differences between the two crab mirelurks.
  12. Fallout 4 loading screen hints: "Most Mirelurks are heavily armored and resistant to most forms of damage, but their faces are vulnerable."
  13. Tenpenny Tower terminals; Exploration Database, Mirelurks
  14. Softshell mirelurks
  15. Behavior of mirelurks in Fallout 4.
  16. 16.0 16.1 Mirelurk Research
  17. The Art of Fallout 4 p. 196: "We really needed to include lobsters, given the location."
  18. Quercus: "My word, a mirelurk hunter! Come here, you big lobster, you. Now, I know you have teeth in your stomach, so I must ask that you don't use them on me."
  19. The Art of Fallout 3 p.}}
  20. Fallout 3 concept art by Adam Adamowicz
  21. Quercus: "I can hardly believe it - a mirelurk king! If only I had a crown for you, adorable slimy galoot. You will have to make do with this throne of a nest."
  22. 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."
  23. Fallout 4 loading screen hints: "Some creatures, like the Mirelurk King, Chameleon Deathclaw and Sentry Bot, can utilize stealth to turn themselves almost invisible and ambush unwary prey."