On the heels of Valentine’s Day this week, I was thinking of how silly it is that when we humans try to make a kissy face, we often end up sucking our cheeks in to make fish lips. And yet, most fish don’t really have lips that look anything like this. And they certainly don’t kiss — or at least in the sense that we think of kissing.

In reality, fish have a variety of mouth types, very few of which look much like our silly imitation of them. As with many animals, fish mouths are specific to what they eat. There is a wacky array of mouth types including everything from a small sucking mouth that doesn’t have anything like teeth and is designed to eat things like algae, to a large toothy mouth that is made for crunching through the shells of its prey.

Then, there is the placement of the mouth. Think of a catfish with its mouth on the bottom that is designed to cruise along the bottom gathering detritus and other small food items. This is categorized generally as an inferior or downward-facing mouth. Then, there are also fish with upward-pointed mouths made to pull in other creatures from the water column. The hatchetfish is a good example of this type of superior-mouthed or upward-facing-mouthed fish. In addition to its upward-facing jaw, it also has a deep scoopy chin to scoop up water along with its prey. There is also a more straight-up mouth type: the terminal mouth type that points straight ahead. These are common in predatory fish like tuna that charge forward to capture their prey. And, maybe my favorite contender for the fish with the best lips, the hogfish. Its lips don’t look anything like a hog but instead look a bit like Lips, the trumpet player from The Muppets with big thick lips that stick out and fierce teeth inside. This “protrusible” mouth type is made for crunching through the shells of crustaceans. Another type is the jawless fish. It isn’t that they don’t have mouths — more that they can’t open and close them in a hinged way but instead have round mouths with rasps or bristles around them.

That covers most of the basic types of fish mouths, though there are myriad varieties of each type. And I haven’t even touched on the types, sizes and orientations of teeth that are designed for anything from grinding to crunching.

Mouth and lip types aside, you might wonder whether fish actually kiss. Most commonly in an aquarium, you might see fish “kissing” the surface of the glass. This is not a display of self-love but rather a way to suck in algae. There are, however, fish called “kissing fish” that kiss each other. But rather than this being a sign of affection, kissing fish kiss to establish territory. They essentially fight by kissing, as their mouths are jagged and rough.

Perhaps when humans make a fish face, they ought to try kissing a fish. Some fishermen believe that this can bring you good luck. Some will kiss the first catch of the day and then release that one, believing that it will result in them catching more fish afterwards. It’s a kind of reverence for the catch.

Whatever the type of mouth, human or fish, happy Valentine’s week to everyone. And now you know a bit more about those silly fishy lips we all make.

Susan Olcott is the director of operations at Maine Coast Fishermen’s Association.