Talk:Sea Dragon Leviathan/@comment-33517231-20171029214633/@comment-34575811-20180206050456

"With few substantial targets in the volcanic cave systems the sea dragon likely ventures out into cooler waters to hunt other, smaller leviathans, cornering them and forcing them deeper, where they are ultimately boiled alive."

From the "Behavior" paragraph in the PDA databank entry. I suppose it doesn't necessariy say they killed the leviathans and brought them back, but rather they maneuvered in a way to make the reapers flee down to the lava zone, where the reapers then either died from the heat or were killed directly by the sea dragon.

Apart from direct in-game evidence, I don't think killing them and dragging them back would be implausible behavior anyway. Plenty of real-life predators will eat some of a kill on the spot then transport the rest somewhere else for safekeeping or privacy from competition, like a nest. Especially if it has young to feed. I believe there are also reaper skeletons in the corridor connecting the Lost River to the Mountains, so judging by that, the sea dragons indeed don't always haul their prey all the way back home.

Also, since these creatures live in a pretty extreme environment, in both pressure and temperature, it may be unhealthy (or at least uncomfortable) to be in reaper waters for too long, so they'd want to go up, grab a meal, then go back. It would make sense if they would make a kill then drag it back with them to chow down in the toasty heat of their primary  habitat.