To Fin or not to Fin


Every salmon has a little adipose fin on its back, between its tail and its dorsal fin. The adipose fin has no bones or spines to fill the thing up. The dorsal fin is poky. The tail fin? Also poky. But the adipose fin is, well, fatty is a good word, I guess. Lipid. Gooey. Salmon have a bloop on their back and nobody knows what it’s for.

In fact, adipose means “fat”. It’s a Latin word that showed up in the English language because, for whatever reason, we needed more words for fat in our language. Heaven forbid we just say “fat fin”.

two_fins2
No blog is complete without a photographic rendering of two fish butts.

You see, when the baby salmon hatches in the river, it grows a bit, and then eventually makes its way to the ocean. After a time in the ocean, its urge to breed blinds it from everything else. It needs to get to its birthplace in that river. It stops eating. It becomes all drive and push. Every one of its organs deteriorate except for its sexual organs. A salmon is essentially a swimming phallus.

And this, biologists thought, is why salmon need that extra energy. Extra fat. An adipose fin.

Of course, as most scientists do, they soon realized they were wrong about the adipose fin. Because, after all, when it comes down to it, what do we truly know about salmon?

A little bit. But as to the adipose fin, biologists still have no idea what the fin does.

So when fish hatcheries became a thing around 1870 in the USA, fish farmers  decided to cut off the adipose fin, so they could determine which salmon were hatchery-raised, and which ones were wild. Fin? Wild fish. No fin? Farm fresh.

But–and I’m speaking hypothetically here–what if these organs have a purpose scientists never even perceived?

Scientists recently discovered that fish with adipose fins will flick their tails 10% more than fish without one. This may not sound like a big deal, but a salmon is a propulsion machine. A tail flick means the difference between jumping a rapid, and not making it. Biologists have also discovered neural pathways amid all that back bloop. They think the adipose fin is a sensor fin. It lets them feel currents (or undercurrents?) they could not otherwise feel.

I am not the only one who remembers the 1970s. Those were glorious days. We loved removing useless things. I know my mother had her tonsils removed. I never did but I’m pretty sure most kids of my era had them taken out. And adenoids. A gall bladder is equally pointless. I’m pretty sure Judi doesn’t have a gall bladder, as a matter of fact.

This doesn’t matter to me overly much; I’m not a lover of adenoids, or tonsils. I have never once seen my spleen or my appendix. If I had a fin on my back, and that fin was filled with “bloop”, I would probably want it my back. Or maybe I wouldn’t. Instead of worrying about the existence of a back foreskin, maybe I should just enjoy what I have?

Here’s a thought experiment: what if scientists in the 1950s had decided the external cartilage on a person’s ear is worthless? Just a decoration. Who needs ear? Sure you could navigate without it. But how much better could you hear with the external ear channeling the sensations of sound? Don’t try this at home, kids. Absence of an ear will only make it harder to hang spark plugs from the sides of your face.

Another thought experiment: is it a short step from removing parts of the body one finds useless, to removing parts of society one finds useless? Is euthanizing people the slippery-slope result of a mindset that cuts fins off the backs of salmon? Of course not! We’d shout. A fish is a fish, but a person is a person, no matter how small.

Don’t be shooting me angry e-mails. I did say this was just a thought experiment.

My grandma and grandpa Farmer never kept anything that wasn’t useful. Their ideas ran contrary to the hard-line “Keep everything” thinking that lots of depression-era folks seemed to have. Their home was not sparse by any means, but definitely uncluttered. Everything had a purpose. If it didn’t, it would be trashed. No sense keeping useful things.

Sometimes, when I think about it I wish they hadn’t decided to live so lean. Tidiness is a good thing, I won’t deny it, but I’ve often wondered what it would be like if I saw a treasured plaything from their childhood, or a scrapbook my grandma’s great grandma kept. But those things were never there. Maybe for some folks memories are like adipose fins: possibly useful to someone, but if necessary, disposable.

Things that are there, but not understood, are like an undiscovered country. Rather than decide something is without use, maybe we just haven’t looked hard enough. Biology is a marvelous place to explore. Maybe there are mysteries yet to be unraveled in the universe. Maybe some of them are right there inside our own bodies. Did you ever wonder what it would be like to have gills?

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