Shabbat 121: The 5 Dangerous Creatures

A footnote to the Who's Who on Rabbi Yosi ben Halafta. And: Amira le-Akum, and how Jews are not responsible for non-Jewish activities on Shabbat. But Jews are responsible for the activities of Jewish children on Shabbat. Also-ran: When a miracle put out a fire on Shabbat, and that's not the focus of the story of putting out a fire on Shabbat. Also: a focus on determining Halakhah based on real-life stories. And: overturning a bowl to do actions indirectly on Shabbat - including to protect against scorpion bites, except that that seems to violate the melakhah of tzad (trapping). The Gemara lists 5 dangerous animals that you can always kill on Shabbat, and then expresses ambivalence re that plan. But isn't this a pre-pikuach nefesh situation? Would it be an exemption to break Shabbat, or an obligation in the fulfilment of keeping Shabbat, to the nth degree?