Board Thread:Questions and Answers/@comment-6050823-20131110204718/@comment-4009941-20131114021333

I would think its eggs hatch inside the body. It would seem more safe for the young with all the dangers on the beaches like Ludroth or Hermitaur who nest in sand. We should also notice the many areas they thrive in, like underground cave river systems, fresh water rivers outside and salt water enviroments. Any one of these areas could be chosen by them just for breeding.

On another note I think they may have a tadpole form. If you look in the kitchen on MHFU or there appears to be a fish(If its a fish) that looks like a plesioth head with fish tail instead of a neck. I think its a  possible tadpole form. Also you can get plesioth scales in pokke so its possible they got it out of the river.

And not sure if it counts but in one of those Felyne Diary cartoon shorts another of these tadpoles(?) was seen with legs only and no arms. I would think of it like a tadpole turning into a frog that grew only its back legs first.

So Pokke and fresh water enviroments get my vote for Plesioth breeding grounds and its possible they may be able to lay eggs safely in these areas if they do with less leviathans in the areas(Until that jerk Baruragaru showed up).