Well it depends on the species lol but Killer whales easily kill Great whites, and pods of the smaller dolphins handle em too, one dolphin alone probably wouldn't be able to kill a great white but...
I'd become a crow. I just read about em and I never knew this but they are actually super smart. http://www.birds.cornell.edu/crows/AP%20HART93%2020Mar10%20cutout_kjm5340.png
None of those were likely depersonalization. Usually it doesn't last only a couple days, that sounds like just a hang over.. You do realize molly comes with a bad hang over right? Also wtf is Molly...