With their ears.
to hear their pray in the water
Yes, and because people just like to hear themselves say "I've hunted lions".
Sea lions are in the family Otariidae ("eared seals"), therefore they have external ears and hear stuff very much the same way we do. The family Phocidae ("earless seals") has no visible ears, but can still hear.
To hear the big scary lions coming to eat them :D
No they don't. They just have very good hearing.
with the roar and the amount of hear they have around there neck (maybe).
It's Hear Our Song by The Chemists
No, mountain lions are unable to roar. Only the big cats - lions, tigers, jaguars and leopards - can roar. Mountain lions can scream but not roar. The scream can only be heard fairly close to the animal,
Yes and from what I hear leprechaun like to eat unicorns as well.
Yes. Cats, birds, bats, lions and even humans without ear lobes can hear perfectly well without them.
it's "hear our song" by the chemists
They have big ears. That is because lions hunt their prey by listening. Lions with better hearing find more food and over time they produce more descendents, which improves the general level of hearing in the species.