Let’s start with the most familiar gang: the bony fish. This class is called Osteichthyes (say that three times fast). Think salmon, trout, tuna, and your pet goldfish. They have skeletons made of, yep, bone. Over 95% of all fish on Earth are in this class. That’s like saying 95 out of 100 kids in the cafeteria are eating pizza.
Then we have the sharks and rays. Their class is Chondrichthyes, which means “cartilage fish.” Their skeletons are made of rubbery cartilage—like your nose or ears. They’re the cool, leather-jacket-wearing rebels of the ocean. No bones, just pure attitude and a killer smile.
And don’t forget the lampreys and hagfish. They belong to Cyclostomata, a class so old they don’t even have jaws. They look like something from a sci-fi movie, with round, sucker-like mouths. These are the “before TikTok was invented” ancestors—ancient, weird, and frankly, a little unsettling.
A Quick Trip to the Pet Store
Next time you’re at the pet store, look at the tanks. The tiny neon tetras? Bony fish. The sleek, predatory-looking catfish? Also bony. If you ever saw a baby shark in a tank (please don’t keep one), that’s cartilage class. The point is: you can’t lump them all together in one biology locker. They’re more diverse than your Spotify playlist.
Fish Production Class 9 Notes at Kelsey Sapp blog
Now, why should you care? Because knowing this makes you sound brilliant at dinner parties. When someone says, “I love fish,” you can casually reply, “Oh, which class? The bony ones or the cartilaginous ones?” Watch their jaw drop—it’s a superpower.
