The hermit crab still resembles its unmutated pre-War ancestor closely both in appearance and habits, with the only major difference being its immense size. Towering head and shoulders over any human, hermit crabs are far too large to protect their vulnerable abdomen by squeezing it into an empty gastropod shell. Instead, they use wrecked vehicles to facilitate their ambush hunting style.
When approached, the crab will attack, utilizing its claws. They will stay stationary, not seeking out prey unless other creatures are in close proximity, in which case the crab will comb the area. This will occur in the case of the Sole Survivor, even if they are hidden. The hermit crabs inflict high levels of damage and have high HP, but are slow-moving enemies. They cannot traverse some landscapes, will not enter buildings, nor climb over obstacles. At times they will retreat to their shell and produce hatchlings in groups of up to six that will aid in their attack.
Hermit crab hatchling
Hermit crab hatchlings are identical to mirelurk hatchlings. They look similar (except the color of the skin), show the same behavior and are equally weak in combat, although they can swarm the player character in large numbers.
Just in front of the north screen of Eden Meadows Cinemas, assuming the resident ghouls had previously been taken out.
Far Harbor settlers may invite the Sole Survivor on a hermit crab hunt in the quest Deadliest Catch. The target will always be at one of the places mentioned above, and initiating the quest is the only way to respawn hermit crabs.
Hermit crabs can be hard to spot with the naked eye, especially when approaching them from any direction but their front side. A power armor helmet equipped with a Targeting HUD will identify any hidden hermit crab immediately.
Another, somewhat more dangerous check involves looking for a civilian suitcase that is stuffed between the tires inside of the Lobster Grill van. If there is one, then the wreck is harmless. However, if the suitcase is rather tucked against the van's roof, then prepare for combat.
Hermit crabs do not seem to have any defense against radiation (whether damage or poisoning) whatsoever.
Dead hermit crab hatchlings can be found scattered throughout Far Harbor, one being on the barrel in front of Longfellow's cabin.