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).

Background:
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.

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“