Lakelurks are mutated snapping turtles that live around aquatic areas like Lake Mead. They attack by using shrieking sonic pulse waves to stun enemies, then rip them apart using their claws. They are fiercely territorial and extremely aggressive, attacking almost anything that comes near them or their nests. They are usually found in small groups of two to three, though can occasionally be found in larger groups comprised of around five to eight. They have a high Perception, which makes them very quick to find potential prey within their immediate area.
Strangely, if they follow their prey into water, they will have no underwater attacks and will only continue to glare. However, if their sonic attack is fired from land, it will pass straight through the water as it does through the air, putting their prey at a disadvantage of not being able to defend themselves.
The standard lakelurk with all characteristics stated above. The largest lakelurk hot spots are Lake Mead and the caves inside Camp Guardian. There are also large groups at Blue Paradise Vacation Rentals and at Ruby Hill mine. About 2-4 can be found down the hill from the cap counterfeiting shack near Lake Mead, and around four lakelurks can be found on the scavenger platform. Four more lakelurks may be discovered just south of the Hoover Dam southern fence line barrier on the eastern side of the Colorado River in a small cave area. At lower levels, lakelurks will rarely drop lakelurk meat when killed. Higher level lakelurks, however, more often than not drop lakelurk meat. The lakelurk shriek has a 50 damage health effect that ignores DR/DT along with a -10 to Perception effect.
The alpha male lakelurk was a sub-species of lakelurk that was to appear in Fallout: New Vegas, but was cut from the game prior to release. It is a stronger form of the lakelurk that is visually identical to the lakelurk king.
The lakelurk king is a stronger variation of the standard lakelurk. While visually similar, the king has slightly glowing eyes, fins, claws, and other protrusions. Also of note is the apparent light coloration resembling "body paint" on its chest and back. It can be found in the Camp Guardian caves in a large room among multiple lakelurk egg clutches. Killing it will cause the other lakelurks in the cave to frenzy and become hostile towards each other.
The following is based on unverified behind the scenes information and has not been confirmed by canon sources.
Cachino makes a reference to Nero "sleeping with the lakelurks," the Fallout equivalent of "sleeping with the fishes," a euphemism implying death coined in older mafia films where someone would have their feet encased in cement, then be thrown into a body of water.