In the newsroom the other day, Dave Davis, one of the sports guys, emerged from his lair, and by way of greeting, I asked him how he was doing.

“Happy as a clam,” he replied.

“How come clams are so happy?” I asked. “I mean, you’re stuck in a shell underwater, can’t move around and visit other clams …”

“You’re right,” Dave mused. “Maybe it should be ‘happy as a lobster.’”

“Naah. Lobsters have it even worse, always fighting with each other, and then you crawl into a trap — boom! Next thing you know, you’re tossed in boiling water. And crabs? Don’t get me started.”

Anyway, I looked it up later, and apparently the full phrase, dating back to the 19th century, is “Happy as a clam in high water.” Now this makes more sense. At low tide, clams and other mollusks are easy pickings for birds and people, but in high water, they’re safe and happy, I guess, in a clamlike sort of way.

The more I thought about it, the more I realized how many everyday expressions are derived from qualities associated with animals.

Clams, it turns out, aren’t the only so-called happy creatures. Dating back to the 1700s, a cheerful person was thought to be as happy as a lark because of that bird’s jubilant song. We now know that birds sing for a variety of reasons — they’re trying to attract mates, sending an alarm, or simply telling rivals, “Back off!” Birds almost never sing just because they’re feeling chirpy.

Likewise, it’s unfair to say that a contented person is as happy as a pig in — well, you know the old saying. It’s sometimes sanitized as “happy as a pig in mud.” Actually, unlike many animals, pigs are quite clean and prefer to do their business away from their living quarters.

As for a dog with a bone, though, I’ll grant you — that’s one happy canine.

Which reminds me of the riddle: What has four legs and one arm? Give up? A happy pit bull. (Hey, all you Staffordshire terrier owners, lighten up. It’s a joke.)

Conversely, as one who has been stung on numerous occasions, I can verify that hornets indeed are angry when you stir up their nest.

As for wet hens, I’m not sure what makes them angry. According to the Urban Dictionary, after farmers took away the eggs, sometimes a chicken would go back to an empty nest and refuse to lay any more. The farmer would then dunk the hen in a tub of water, making it mad enough to resume laying.

If you ask me, this sounds like a lot of bull. I think you’d have to be as crazy as a loon to believe it. Who knows: Maybe they’re just crying crocodile tears.

I will grant, though, that many expressions are spot on.

Oxen are indeed strong.

Cats often are scaredy.

Mice usually are quiet, but I’m not sure a church mouse is any more silent than a run-of-the-mill mouse. That’s a horse of a different color.

Mules can indeed be pretty stubborn, but calling an umpire blind as a bat? Horsefeathers! Bats can see just as well as humans, but at night they rely on internal sonar systems instead of their eyes to navigate.

And horses don’t become more famished than other animals, so if we miss a meal, why do we say we’re hungry as a horse?

I’ve also come across a few junkyard dogs in my time and found them no meaner than lapdogs.

Bees and beavers may seem busy, but many other creatures are just as frenetic.

Slippery as a snake? Nope. They’re dry and no more slippery than an aardvark, and that’s the doggone truth.

Doggone, by the way, is a polite alternative to an expletive that takes the lord’s name in vain.

Anyway, I guess being happy as a clam is just another way of saying everything is ducky, but frankly I don’t think swimming around in a pond all day and preening your feathers is all that it’s quacked up to be.