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The ocean is filled with all kinds of creatures, even dogs and cats. Well, dogfish sharks and catsharks, that is.

Both species fall under the shark umbrella, but they're named after different household pets.

So, how do you tell the difference between a cat and a dog under the sea?

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Well, both are sharks, but they definitely aren't 100 percent the same.

This is a catshark.

This is a dogfish shark.

According to the ReefQuest Centre for Shark Research, here's the best way to tell the difference between catsharks and dogfish sharks:

  • Catsharks have what's called an anal fin, which is a fin close to their tails on their undersides. Dogfish do not.
  • Dogfish have dorsal fins very close to their heads; catsharks' are further back.
  • Catsharks are slimmer than dogfish.
  • According to Oceana, dogfish eggs hatch inside them, so they birth live young. Meanwhile PBS Nature reports that catsharks lay egg cases that hatch later.
  • Dogfish are generally bigger at around 3 to 4 feet, according to Oceana. Catfish ring in at around 2.5 feet, according to PBS Nature.

Where their names come from is also a big difference.

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Oceana reported that dogfish sharks were so named by fishermen who saw the sharks chasing down prey in dog-like packs. Catsharks, on the other hand, are named for their cat-like almond eyes, per Smithsonian.

They look just like a cat's.

See?

But as the Smithsonian noted, technically all sharks have "cat eyes" because both sharks and cats have the same reflective eyes that help them see in the dark.

That's what makes them look super creepy when you shine a light on their eyes.

So all sharks have cat eyes, but only some sharks are catsharks. And even one "dogfish" is a catshark, according to BBC. Once upon a time, the lesser spotted dogfish was mistakenly labeled as a dogfish.

Proper examination using the above criteria later uncovered its catshark status.

It basically brought back the old days of Nickelodeon's "CatDog" with that kind of scientific confusion.

Is it a catshark or a dogfish???? The world may never know! (It's a catshark.)

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Hopefully all of this cleared up any dog/cat shark confusion.

Now, just don't get us started on whale sharks or false killer whales.

The ocean animal naming system is too much.

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Add your name right now to ban the trade of shark fins in the U.S. and protect our oceans with Oceana.

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