Beaver

What you're getting

Look, this isn't a toy beaver—it's a proper look at how beavers actually behave. When one gets startled, it does something rather brilliant: it dives fast and whacks the water hard with that flat tail of theirs. The noise it makes is genuinely loud, travels miles both above and below the surface, and basically screams "danger" to every other beaver within earshot.

Once that alarm's sounded, the nearby beavers get the message and disappear underwater. Smart creatures, really.