Finding Out about Dory: 5½ Facts on the Blue Tang

SCIENCE

While you’re sitting around waiting for the movie start, here are 5½ facts you can drop about Dory’s species, the blue tang. (Mental Floss)

How do scientists study blue tangs? With coral reef surveys like this one.

Educators, scroll down for a quick list of key resources in our Teachers’ Toolkit.

This photo of a blue tang clearly shows the caudal spine slightly extended near the fish’s tail. Photograph by DerHans04, courtesy Wikimedia. CC-BY-SA-3.0,2.5,2.0,1.0

This photo of a blue tang clearly shows the caudal spine, yellow, slightly extended near the fish’s tail.
Photograph by DerHans04, courtesy Wikimedia. CC-BY-SA-3.0,2.5,2.0,1.0

Discussion Ideas

  • 1. Blue tangs aren’t always blue, and they’re not always tangs.
    • Juvenile blue tangs are bright yellow. And adult blue tangs can actually modulate their color based on environmental conditions. Under stress, for example, their blue coloration deepens to violet and the black marks may become slightly bleached.
      • Blue tangs get their color from cells called iridiphores, a type of chromatophore. Iridiphores are crystal structures of guanine (the famous G in our DNA tetrarchy of guanine, cytosine, adenine, and thymine). The crystalline arrangement reflects light at a specific spectrum and determines the animal’s color.
    • Dory’s species of blue tang, Paracanthurus hepatus, has many different names: blue tang, doctorfish, common surgeon, regal tang, palette surgeonfish, royal blue tang, hippo tang, flagtail surgeonfish, Pacific regal blue tang, and blue surgeonfish.

 

  • 2. Blue tang are everywhere and nowhere.
    • Blue tang are not listed on the IUCN list of endangered species; their populations are pretty healthy and they’re of “least concern.” However, as a nice sentence on Wikipedia notes, “the species’ range is broad, but it is common nowhere.”
    • Blue tang are entirely helpless when they hatch, lacking a pigments, eyes, a mouth or even a heartbeat. They drift with the currents for about five hours after hatching.

 

 

  • 4. Blue tangs are poison.
    • Blue tangs often carry a toxin called ciguatera. Symptoms of ciguatera poisoning are usually limited to vomiting and diarrhea, but may also include more serious symptoms such as headaches, muscle aches, and even hallucinations and heart and breathing problems.

 

  • 5. Blue tangs will cut you.
    • As its “surgeonfish” name indicates, blue tangs are handy with scalpels. The fish have caudal spines—very sharp spines that can be extended from either side of their caudal peduncle (the area where the tail joins the body). The caudal spine contains toxins that can cause a debilitating pain to small predators and uncomfortable irritation and pain in humans. Blue tangs extend their caudal spine and thrash around when threatened.
      • The defense mechanism is useful. Some parrotfish, which are similarly colored but lack caudal spines or toxins, often join groups of blue tang for protection.

 

 

Blue tangs can live more than 30 years in the wild. In aquariums, where they more readily acquire diseases, they generally survive about 8 to 12 years. The beautiful blue tang lives in the Ulm Zoo in Germany. Photograph by H. Krisp, courtesy Wikimedia. CC-BY-3.0

Blue tangs can live more than 30 years in the wild. In aquariums, where they more readily acquire diseases, they generally survive about 8 to 12 years. The beautiful blue tang lives in the Ulm Zoo in Germany.
Photograph by H. Krisp, courtesy Wikimedia. CC-BY-3.0

TEACHERS TOOLKIT

Mental Floss: Understanding ‘Dory’: 5 Facts About the Pacific Blue Tang

Nat Geo: Coral Reef Fish Survey Simulation activity

Nat Geo: Coral Reef Food Web illustrations

Animal Diversity Web: Paracanthurus hepatus

4 responses to “Finding Out about Dory: 5½ Facts on the Blue Tang

  1. Pingback: What Did You Read in 2017? | Nat Geo Education Blog·

  2. Pingback: The Blue Tang Fish ‘Dory From Finding Nemo’ Is… | JustaFact·

  3. I really like this sweet name… BLUE TANG!!! sounds like a very mischievous kind of fish… But it has poison in it’s spine… Be careful before making it your dinner and lunch… When any spices change their color is a scientific process but for me it’s like something very magical… Blue Tang changes its color during depression due to chromataphore…..

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