Gulpers are mutated salamanders that roam the Island. They can hang on trees, in order to take their victims by surprise. They can also slide through swamp-like areas and hide underwater. They tend to stay near bodies of water, as said by Old Longfellow and can grow to the size of deathclaws.
Having movement patterns similar to deathclaws, when engaged in combat, they will rush towards the player character, trying to dodge bullets if shot, and will attack with their paws and large mouth, or even do a slide attack where they hit the player character with their snout. Gulpers can also be seen hanging upside down on tree branches, dropping down to attack the player character when they come near. The Wasteland Whisperer perk can be used to pacify them. Gulpers are also able to slowly regenerate health.
When first arriving at Far Harbor, the player character must help the harbormen defend against a horde of gulpers, radroaches and anglers.
These gulpers have a lighter coloration, less Damage Resistance and less health and power than their elders. The lighter coloration makes young gulpers much easier to spot while hidden, as the light coloration usually clashes with their surroundings.
Gulper devourers are huge creatures roughly on par with deathclaws. They will often charge at the player character, dealing knockback on impact before following up with devastating melee attacks. While posing a considerable threat, they have a weak point: their soft bellies, quite similar to that of a deathclaw.
Gulper devourers level with the player character and are therefore immune to the Wasteland Whisperer perk.