Though if we accidentally left out any cannibalism or marine life eating people options, please rectify that error! We are kind of ditzy, you know.
Anyway... If you are aspiring to become a proper Cnidarian, here are some movies that might help you do so. I'll stress might, but good luck to you.
SPOILERS: Most of us were good, some of us are jerks, there are probably a few spoilers, including end of movie spoilers, herein... But, who knows. I'm not sure I would trust a word that comes out of any of these peoples' mouths.
Current contributors (listed in order of chronic mouthiness): St. Sailing (15), St. Hemmingson (8), St. Klock (4), and St. Young (2).
1. Soylent Green: it will teach you one way to reduce the overpopulation of human scum, while simultaneously alleviating "starving artist" syndrome.
2. The Devil in Miss Jones: perhaps one of the first "literary" porn movies to feature ATM, a possible form of re-processing human extract as food.
3. Planet of the Apes: Charleton Heston shows much of his manly 60s figure instead of wearing that gay neck scarf and hat in Soylent Green (do damn dirty apes make a better lunch?).
4. Silent Running: Pre-Star Wars cute robotos and lonely Bruce Dern in space, maintaining food for no one.
5. Jaws: Instead of people eating people, big fish eats people.
6. Logan's Run: perfect post-apoc solution to population control without resorting to People Scoopers, swinging 70s attitude toward free sex, British accents despite being in Washington DC, crazy android that freezes people to make food out of them.
7. Pretty Baby: sexy 12-year-old Brooke Shields as brothel man food.
8. Eat the Rich: socialist film with Motorhead that knows which way to trend on who to eat first.
9. The Cook, The Thief, His Wife and Her Lover: elegant, smutty, and one of the most feel-good moments of vengeance against a human that can be had.
10. Haxan: learn how you will be treated as a Cnidarian, despite supposed Freedom of Religion (Mormons have more freedom than we do!).
11. Fear and Loathing in Las Vegas: you actually won't remember it, because you'll be lost in acid flashbacks all the way through it. It's a subconscious thing.
12. Parents: for fine lessons in upbringing children, and because it freaked St. Young out and made him hate it when I showed it to him.
13. Jesus Camp: see true super-scary cults in action, and be glad there are harmless Jellyfish worshippers in the world.
14. Orca: Farah Fawcett's leg becomes Shamu food. Horrid miscarriage scene of whale fetus that sets off the killer whale revenge story a la Moby Dick.
15. A Boy and His Dog: classic Harlan Ellison novella with a young pre-Miami Vice Don Johnson where he and his psychic K9 have a cannibal feast at the end.
16. Eating Raoul: similar to #9, but more of a case study of one possible methodology of eradicating problematic humans in an economical fashion.
17. Titus: of course in ancient Rome, this sort of thing would hardly be all that surprising anyway (they knew how to have fun).
18. Silence of the Lambs: all films with the "Hannibal Lecter" character should be watched (as if this needs any further elaboration...).
19. Deep Blue Sea: similar to #5 but much cheesier - the premise being that some silly arrogant research scientist decides to make a pair of white sharks as smart as humans, in order to study neurological theories, without EVEN ONCE considering the possibly that she has "knocked the human race off the top of the food chain", as one horrified coworker puts it (this film is of course only enjoyable from the perspective of rooting for the sharks...).
20. Delicatessen: Human scum have what's coming to them - life in the sewers, and systems for eating each other.
21. Coffee and Cigarettes: It's good for the soul to occasionally watch OTHER people do some of the same neurotic twitching you do.
22. Avatar: pop and Hollywood but includes a feel-good well-deserved butt-kicking of humans who damn well deserve it for fucking with Nature Preserves. Plus when I saw it in 3-D a floating Jellyfishy thing landed on my hand.
23. The Hunger: Miriam associates with bipedal messengers of Cnidaria, and is so artistically elegant that we overlook her weakness of screwing over the humans she doesn't feed on because she cares about them.
24. Bubbahotep: if you are a skeptic who thinks Space Jellies may not exist, you'll believe in them just like you believe in Elvis and a black JFK by the end of this.
25. Ravenous: the Wendigo is also allied with Cnidaria, and helps keep the wilderness populations of humans at a minimum.
26. The Monolith Monsters: a reminder that things will come from outer space to kill off humans and destroy all their works. This one was stopped but it's only the first.
27. Godzilla vs. Biollante: the scientist has the arrogance to gene-splice a rose with his dead wife! That alone justifies multiple cities being destroyed.
28. Gamera (1995 + sequels): about as Cnidarian as can be, even if a fire-breathing space turtle is standing in for Fiery-Raining Space Jellies and hasn't YET fully decided that humans are the biggest threat to the planet.
29. Mononoke Hime: humans are just the most disgusting polluting destructive menaces to be found, and they curse themselves by cursing all other life.
30. Tideland: If you look at people through the eyes of a little girl (as opposed to looking through the perspective of one) you might understand why the Jellyfish should just come now and get it over with, damn it.