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Understanding Dory: 5 Facts About the Pacific Blue Tang

If seeing Finding Dory is part of your weekend plans, you’re not alone: Box office analysts are predicting that the new Pixar movie will likely open between $115 and $120 million. While you’re sitting around waiting for the movie start, here’s a little bit of knowledge you can drop about Dory’s species, the Pacific Blue Tang.

1. IT HAS A LOT OF ALIASES.

Though the fish's scientific name is paracanthurus hepatus, it's also known as Pacific blue tang, royal blue tang, hippo tang, regal tang and palette surgeonfish, among other things.

2. THEY HELP KEEP CORAL REEFS HEALTHY.

Blue tangs eat nothing but algae, and they’re instrumental in keeping the algae levels on coral down to a manageable level. Without the blue tang there to eat their fill, algae could overgrow and suffocate the reefs.

3. DON’T EAT DORY.

The Paracanthurus hepatus has poisonous flesh. Eating it may cause ciguatera, a foodborne illness passed on by certain reef fish that have toxins in its flesh. If you happened to accidentally ingest one, it probably wouldn’t kill you—but you’d likely come down with a bad case of diarrhea.

4. IT'S NOT ALWAYS BLUE.

Despite its name, the blue tang is not always azure. It can change color at night because of the way light is reflected from the pigments in its skin, becoming “whitish with a shade of violet.” Researchers believe its nervous system is less active at night, which may also affect its coloring. And juvenile blue tangs are bright yellow, which darkens as they mature.

5. IT CAN CUT YOU.

She may seem sweet in the movie, but the real-life Dory can (and will) cut you. The blue tang has a sharp spine that can stand erect as a means of self-defense. Because of this sharp, scalpel-looking spine, the blue tang is part of a family of fish known as “surgeonfish.”

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Goldfish Can Get Depressed, Too
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Don’t believe what Pixar is trying to sell you: Fish are not exactly brimming with personality. In aquariums, they tend to swim in circles, sucking up fragments of food and ducking around miniature treasure chests. To a layperson, fish don’t appear to possess concepts of happy, or sad, or anything in between—they just seem to exist.

This, researchers say, is not quite accurate. Speaking with The New York Times, Julian Pittman, a professor at the Department of Biological and Environmental Sciences at Troy University, says that fish not only suffer from depression, they can be easily diagnosed. Zebrafish dropped into a new tank who linger at the bottom are probably sad; those who enthusiastically explore the upper half are not.

In Pittman’s studies, fish depression can be induced by getting them “drunk” on ethanol, then cutting off the supply, resulting in withdrawal. These fish mope around the tank floor until they’re given antidepressants, at which point they begin happily swimming near the surface again.

It’s impossible to correlate fish depression with that of a human, but Pittman believes the symptoms in fish—losing interest in exploring and eating—makes them viable candidates for exploring neuroscience and perhaps drawing conclusions that will be beneficial in the land-dwelling population.

In the meantime, you can help ward off fish blues by keeping them busy—having obstacles to swim through and intriguing areas of a tank to explore. Just like humans, staying active and engaged can boost their mental health.

[h/t The New York Times]

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The Shocking Science of Electric Fish
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Like slippery Pokemon, electric eels can produce shocks strong enough to incapacitate large predators. But where do these electric fish get the power to generate such high-voltage attacks?

In a recent video, TED-Ed explains the volatile biology at play. Electric fish like electric eels (which are more closely related to catfish than actual eels) all contain at least one electric organ. This organ is packed with disc-shaped cells called electrocytes. These cells naturally release sodium and potassium ions which create a positive charge inside the cells and a negative charge outside them. But when electric fish send signals from their brains to these organs, it opens up the cells' ion channels, allowing the ions to re-enter. The result is an electrocyte with a positive interior and a negative exterior on one side and a negative interior and a positive exterior on the other—basically a biological battery. Once these cells are charged up, fish can use them to disrupt nearby electric signals, detect other fish, and even paralyze prey.

Fish aren’t the only animals that use electricity to their advantage. The oriental hornet, for example, makes electricity out of sunlight, while some spiders harvest charged particles by coating their webs in electrostatic glue.

[h/t TED-Ed]

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