Mirelurk (Fallout 3)

Mirelurks are mutated horseshoe crabs living in the Capital Wasteland in 2277.

Biology
Mirelurks are descended from Chesapeake Bay horseshoe crabs. The full scientific classification of the mirelurks is Kingdom: Animalia, Phylum: Arthropodia, Subphylum: Crustacean/Chelicerata, Class: Merostomata/Malacostraca, while Order, Family, and Genus are left undetermined due to their mutation. The Subphylum and Class are disputed in an Enclave Officer's Field Research terminal, as he believes horseshoe crabs and blue crabs both evolved into mirelurks, due to their DNA/RNA samples having markers from two different Subphyla and Classes. Furthermore, he and the player both fill in the missing Order, Family, and Genus with the same answers (on the terminal, and in a Science dialogue check after completing the mirelurk portion of The Wasteland Survival Guide quest): Scylla serrata horrendus.

Mirelurks are always found in aquatic areas such as the mouth of the river Potomac and the river itself. If not in an aquatic habitat, mirelurks have been seen in dark, cool areas, like caves, metro tunnels, and derelict facilities (Anchorage War Memorial) However, mirelurks do not reproach from light; they can be seen during the day, swimming in rivers and walking along the banks. This is especially true around Arefu and the Anchorage War Memorial.

Gameplay attributes
All mirelurks, except for mirelurk kings, are surrounded by a thick shell which is difficult to penetrate, even with powerful ballistic weapons such as the Gauss rifle. Their only weak spot is the face, but the area is small and difficult to hit. When charging, mirelurks will lower their head to protect this area. However, they will swing their heads up during the attack animation, exposing their faces. Low level players will find mirelurks to be among their deadliest enemies.

Mirelurks are extremely territorial, so if anything trespasses, they will attack it until it is dead. Even if the trespasser makes a run for it, the mirelurk will still pursue them ferociously.

Mirelurk meat, especially the soft shell variety, is highly nutritious and grants some of the highest HP replenishment of any food in the game. This is reinforced by Grandma Sparkle, as she will tell the player that mirelurk meat is "the best meat in the wastes". Both are slightly radioactive, but no more than typical food. Chefs throughout the wasteland have developed many culinary uses for mirelurk; the most prominent being the creation of mirelurk cakes. In fact, a recipe for them can be found in a fridge in the Anchorage War Memorial.

Mirelurk
The most common type of mirelurks have a whitish-grey shell, are about a head shorter than a normal human, and walk slightly slower than a human. Mirelurks fight with their claws and lack ranged attacks.

Additionally, at close range they can charge forward in a brief burst of speed for a headbutt, which also makes it impossible to target their face. However, their face is most vulnerable in the seconds after a headbutt, when their 'head' is raised.

‡ Due to their hard shells, shots on the torso only do half of the normal damage.

Mirelurk hunter
A much larger, reddish-brown colored version of mirelurk. In addition to their two main arms, hunters also have two pairs of small, segmented vestigial appendages growing out of their chest. Mirelurk hunters inhabit the Potomac River in the northern wastes and several sewers and caves near the metropolitan area of the Capital, along with a good number in the Anchorage War Memorial. Hunters are very aggressive and are more difficult to kill due to their increased strength, speed, and health.

‡ Due to their hard shells, shots on the torso only do half of the normal damage.

Mirelurk king
Mirelurk kings are different from other mirelurk variants, mainly because they do not resemble their crab-like "subjects". They are not crabs, but are mutated snapping turtles that appear more humanoid and do not have a heavily armored carapace, making them easy to distinguish from standard mirelurks. They are possibly a separate species in a symbiotic relationship with the crab-like mirelurks.

Mirelurk kings have a sonic projectile attack that disregards damage resistance and causes lots of limb damage to the subjects head.

Unlike Mirelurks and Mirelurk Hunters, they cannot float in water.

† Torso shots only do 2/3 of the normal damage.

‡ Instantly cripples target head. Cannot be used if their head is crippled.

Nukalurk
A mirelurk hunter variation that is only found in the Nuka-Cola Plant. They are oddly colored, having a dark blue exoskeleton stippled with glowing blue features along certain regions of their bodies. This coloration is probably due to prolonged exposure and or consumption of the radioactive Strontium isotope that was used to color Nuka-Cola Quantum before the Great War.

Their meat is notable for a small boost in AP as well as radiation and health; 4 rads, +10 AP, and +20 HP. However, only 10 nukalurks appear in-game, limiting the amount of meat available to no more than 10.

‡ Due to their hard shells, shots on the torso only do half of the normal damage.

Swamplurk
Swamplurks (designated "mirelurk" in-game) are a variation of mirelurk which inhabit the swamps of Point Lookout. They are visually identical to mirelurk hunters except for their size, their green-tinged shells due to the swampy environment and the lack of vestigial limbs on their abdomen.

‡ Due to their hard shells, shots on the torso only do half of the normal damage.

Swamplurk queen
Swamplurk queens (simply called swamplurk in-game) are a variation of the Capital Wasteland's mirelurk kings that inhabit the swamps of Point Lookout. Like the mirelurk kings, they are mutated from snapping turtles native to local rivers. They look extremely similar to kings, distinguishing traits being a mossy coloration and strangely shimmery glowing yellow eyes.

Unlike mirelurk kings, the swamplurk queen spits acid from its mouth, similar to a centaur. Although not radioactive, this acid is highly damaging. They are most likely female and therefore responsible for breeding.

Strangely even with its lack of clothing the Swamplurk queen can be pickpocketed allowing for the player to reverse pickpocket explosives for an easy kill, if they can get close enough with a sneak. However this results in a negative karma.

† Torso shots only do 2/3 of the normal damage.

‡ Cannot be used if their head is crippled.

Catfish mirelurk
A humanoid, mutated catfish known as a "catfish mirelurk" also appears in The Art of Fallout 3, the art book available with the collector's edition of Fallout 3.

Appearances
Mirelurks appear in Fallout 3 and its add-on, Point Lookout.

Bugs

 * Mirelurks killed in water will often flip over on their fronts and twitch. This is purely a graphical glitch related to their wireframe. Sometimes they will twitch so much they fall right through the floor, or become trapped in walls and doors while constantly playing a collision noise that can alert other enemies.
 * Sometimes when Mirelurks are killed on land, body parts will sink into the textures on the floor, as much as half their body, and the remaining parts will flail and bounce.

Behind the scenes
A mire is a tract or area of wet, swampy ground, bog or marsh. So the mirelurks' name is fitting, as they tend to lurk in mires.