Trapped Animal Puns

I'm a dad and I like telling it, so I guess that's qualification enough. I heard this joke about 26 years ago, and I still laugh at it. Slightly long, so don't hate me.

A guy that lives alone decided that he wanted to get a pet. He went to a pet store in his city to see what was available. The man tells the associate at the store that he wants a pet, but he doesn't want an "ordinary" pet like a cat or dog, he wants something unique. The associate asks the man if he by chance has a swimming pool at his house, and the man replies that he indeed does have a pool. The associate says, "Great! I've got just the pet for you. Actually it is two pets -- two beautiful porpoises. And these aren't ordinary porpoises, either. They will never die, but there is one small catch. To keep them alive, once a year at noon on July 1, you have to feed each one of them an immature sea gull, before the birds have learned to fly." The associate tells the man that he shouldn't worry about the annual feeding, though, because the associate will always make sure he has two birds available for the man every year on July 1.

The man buys the pets, fills his swimming pool with salt water, and really enjoys the companionship of the porpoises throughout the year. On June 30, the man calls the pet store to make sure the two birds are available, and sure enough they are. The next day, he goes to the pet store at 10 a.m. to purchase the birds, and while he is inside the store he hears a lot of commotion coming from just outside the store. He goes to the front of the store to see what's going on outside, and he finds that there is a huge, ferocious lion trying to get into the store through the front door. Luckily, the door swings outward from the store, so the lion can't get it open. The police call the store associate to tell him what has happened. The main attraction (the lion) from the state zoo just up the road from the store had escaped, and the lion could sense all the small animals that were inside the pet store, so he was trying to get into the store to eat them. The police are waiting for the zoo's lion tamer to show up and get the animal back into captivity.

Meanwhile, the man who was at the store to buy the birds to feed to his pets was getting really anxious. He was trapped inside the store, there was no other exit, and the time was quickly approaching noon. The associate reminded the man that he absolutely had to feed his pets at precisely noon, otherwise th