Now that I have your attention with that provocative title I wanted to share this Ted-ED video about the feeling of pain: How do animals experience pain.
I found it fascinating, but especially its description of nociception vs the cognitive feeling of pain. And some animals appear to be making decisions about pain (as in the octopus both protecting an injured limb but also deciding to use it to catch prey).
And I don't think octopuses can be Epicureans... Or do I?
Enjoy.