I watched this apocalyptic cartoon-film in the 2nd half of the 80’s (I believe on Belgian French TV). There’s a scene with a boy (main charachter?) who finds a creature which looks like a big seal but has a big long cylidric kinda noise/mouth.It ends up dead by being taken by some long plants hanging on the ceiling in a cave; In another scene the boy is uncounsious laying on the ground and sees a someking of gigantic kinda wasp and in a few seconds there are a hundreds of these creatures flying in front of the boy.