Pardon my ignorance ... A lip is apparently a very sensitive tactile device - as it at-least serves to warn it's owner they may just be about to consume something that could cause injury. Primates (including humans), dogs, cats, sheep, buffalo, elephants, some fish, octopodes - to name a few, have a lip.
How have lips evolved to be nearly ubiquitous across animals? Why have they evolved into a beak/bill in some birds & fish? What niche/purpose do they fulfill?