Symbiotic Strategies
Video Segments: The Secret World of Sharks and Rays

These brief video segments can be used alone or in combination, to introduce a topic or to spark discussion among your students. The video segments can be adapted for any grade level – suggested focus questions are provided. Stream the video segments from the playlist below, or scroll to the bottom of the page to find downloadable QuickTime versions of the videos. These videos are also used in the lesson plan Symbiotic Strategies (grades 9-12).

Sharks and their biological cousins, the rays, are among the highest-profile denizens of the deep. But sharks are not the solitary killing machines that popular movies and the press might have us believe. In their marine environment, sharks coexist with numerous other species – many of whom flock to be near the sharks, rather than running from them in fear. These excerpts from the NATURE episode “The Secret World of Sharks and Rays” examine the interrelationships between sharks and other marine species. In many of these cases, the interaction between two different species mutually benefits each species. But humans, too, have become an increasingly important player in the lives of sharks – and as they are increasingly hunted for their fins, sharks are actually becoming more endangered than they are dangerous. The impact on the marine ecosystem that would result from the disappearance of sharks would be devastating, but there is still time to save these magnificent creatures, and the ecosystems that depend on their existence.

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Suggested focus questions:

Clip 1: Shark and Turtle

  1. How does the turtle protect itself?
  2. What relationship is held between the tiger shark and the loggerhead turtle?

Clip 2: Unlikely Travel Companions

  1. List three ways in which being near a shark might be beneficial to a fish.
  2. What is one way that a shark might benefit from a fish (other than as prey)?
  3. Classify each shark-fish relationship shown in this clip as commensalism, mutualism, or parasitism.

Clip 3: Sharks and Fishermen

  1. How have sharks become trained to follow fishermen?
  2. Describe how the following species pairs interact in the clip: fishermen/fish; sharks/fish; sharks/fishermen.

Clip 4: Collapse of Sharks

  1. Why are shark populations in danger of collapse?
  2. How has the relationship between sharks and humans changed over time?
  3. What might happen if the shark fin trade continues unchecked?

Clip 5: Sharks in our Future

  1. Describe the type of tourism seen in this clip.
  2. What benefit do these businesses provide to: sharks? To local populations? To tourists?
  3. How might these businesses help prevent the collapse of shark populations?

Downloadable QuickTime versions of the video segments:
(Note: To download a video, right-click on the video title and click “Save Link As…” or “Save Target As…”. On a Mac, press the CTRL key and simultaneously click the mouse, then save the link.)

Clip 1: Shark and Turtle

Clip 2: Unlikely travel companions

Clip 3: Sharks and fishermen

Clip 4: “Collapse of sharks

Clip 5: “Sharks in our future

  • Deborah


  • dasha

    i thought that was awesome. but sad too. i liked it. helps me with my school work.


    heyy guys if u see this im at jjh :] ooh ya this page was good

  • alexandra cromwell

    interesting. helped with homework

  • JLCH

    It Was Awwwwwwwwwsome That was Cool that the prey became the hunter It Was Coolz

  • kayla romano

    dont kill sharks. thats f-ed up yo.

  • j. williams

    This video showed symbiotic relationships with sharks and other organisms that i didnt know existed.


    WOW! This is a wonderful vidio full of so much helpful information! :)

  • Eddie

    This was not boring. It was very fascinating. Those people don’t know what they are saying. It showed me the good side of sharks. Now I want to go out and swim with them. :P

  • Desiree

    Great for biology students

  • sadie

    before people go off sayin this video is boring they should learn how to spell or atleast realize the importance of the video and that what these heartless people are doing to animals all across the world is wrong and that it needs to be stopped.

  • Nena

    this is lame!

  • haliegh

    i think these vidoes are pretty cool espically for learning new thing for different people
    i think different people should watch these videos wore often and comment their or your opinion to what you think these video ratings are

  • Ginger

    This video and activty are great. My kids loved it. I love using PBS and NOVA activites in the classroom

  • molly mcfly

    i sat thru this whole thing and enjoyed it. im not a teacher. im a molly!

  • andy six

    i sat here and thought it was chill but not the chill although the loghead t was cool biting at the shark that was amazing.

  • LA Web Design,Los Angeles Web Design

    fantastic publish, very informative. I wonder why the other specialists of this sector don’t realize this. You must proceed your writing. I’m confident, you have a great readers’ base already!

  • Hayden Wolfe

    i thought it was sad that some sharks are still alive when there fins get cut off which is why we should ban together and help save sharks

  • lucas Wulf

    SHARK HUNTING RUINS the natural Ecosystem so all of you Shark Hunters you are KIlling natuer right now. :(

  • D’Asia Cox

    this video was amazing the loggerhead turtle won the shark swim away.

  • Megan scheffe

    So sad! Why do people have so much value for shark fins!? If they keep doing this the sharks will eventually go extinct

  • Mark Villanueva

    The turtle protected itself with its jaws to fight off the shark. Thats an example of predation because the prey (turtle) was being preyed upon the predator (shark) but roles switched later on.

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