Sharks are a Keystone Species

California Standards

Grades 9-12
Biology/Life Sciences,
(a) Biodiversity
(b) Analyze changes in an ecosystem;
(c) Fluctuations in population size in an ecosystem

NETS-S Technology Standards Addressed

1. Facilitate and Inspire Student Learning and creativity
2. Design and Develop Digital-Age Learning Experience and Assessments
3. Model Digital-Age Work and Learning
4. Promote and Model Digital Citizenship and Responsibility

This lesson Plan is for a 2 Week Group Project that follows the study of The Oceans in their textbooks.
This research project will allow the students to explore the answer "What would happen if sharks disappeared",  and requires the students to answer the following questions in their project:
What would  happen to the oceans by
the loss of the large sharks, as top predators  in shaping ocean ecology?
  • This will have what set of effects in the ocean?
  • This will have what set of effects on land for local ocean fishing populations
  • This will have what set of effects as a global occurrence?
  • This will have what effect on the global economy?

When most people think of sharks they often think of terror, shark attacks, and blood. In reality, the odds of being attacked by a shark are very small. In the US, the odds of being attacked by a shark are approximately 1 in 6 million. You are more likely to get struck by lightening, die from falling down the stairs, or drown in your own bathtub. In the first part of this lesson, students will become aware of how rare shark attacks really are.

 In the project part of this lesson, students will explore the importance of sharks in an ecosystem. Ecosystems are typically composed of a number of species and some of the species present in an ecosystem are very important for maintaining the structure of that ecosystem. For example, if one important species is removed from an ecosystem, the entire ecosystem can be disrupted. Such important species are often referred to as keystone species. A keystone species can be a top carnivore that keeps the size of prey populations in check, important plants that support insects that are prey for birds and bats, or any other organism that supports a number of other organisms in the ecosystem. If the population of a keystone species is removed or decreases, other species in that ecosystem will be affected and the species that are supported by the keystone species will disappear.

The protection of keystone species is essential for the maintenance of ecosystem health. Protecting a keystone species protects that keystone species and all of the other species that rely on that keystone species.

 In many aquatic ecosystems sharks are keystone species. In other words, the removal or decline of sharks in an ecosystem will affect many other organisms in that ecosystem. Tiger sharks provide a good example. Tiger sharks will eat almost anything dead or alive, and they consume a large number of sea turtles. Sea turtles consume large amounts of sea grass, and if sharks did not eat sea turtles it is possible that the sea turtles would overgraze the sea grass. If there were too many sea turtles and the sea grass was overgrazed, many of the animals that rely on the sea grass, such as fish, would disappear. If animals such as fish disappeared, animals that eat fish, such as the bottlenose dolphin, would also disappear. Thus, by simply removing one species, the tiger shark, the entire ecosystem is affected and many of the species will disappear from the ecosystem.

Oceans cover more than 70 percent of our planet yet they make up one of the least explored regions on Earth. Through the Tagging of Pacific Predators program (TOPP), scientists hope to both assess and explain the migration routes, ecosystems and diversity of our oceans’ species.

Partnering the National Oceanic and Atmospheric Administration (NOAA) with Stanford University and the University of California, Santa Cruz, TOPP began in 2000 as a project for the Census of Marine Life. As part of TOPP, researchers attach satellite tags to elephant seals, white sharks, giant leatherback turtles, bluefin tuna, swordfish and other marine animals. The tags collect information, such as how deep each animal dives, the
levels of ambient light (to help determine an animal’s location) and interior and exterior body temperature. Some tags also collect information about the temperature, salinity and depth of the water surrounding a given animal to help scientists identify ocean currents. The tags send the collected data to a satellite, which in turn sends the data images to computer experts andscientists. They use this information to create maps of migration patterns and discover new information about different marine ecosystems.

The information collected by TOPP offers rare insights into the lives of marine animals. Without TOPP, that information would otherwise remain unknown. With TOPP, scientists are developing a working knowledge of the particular migration routes animals take, as well as the locations of popular breeding grounds and the environmental dangers faced by different species. TOPP has shed light on how we can better protect the leatherback turtle and other endangered species. It has also been used to help ensure the sustainability of ocean fisheries.

Optional but Recommended: After the presentation of the group projects, conclude this lesson with by viewing the multiple
Award-Winning Movie about the need to preserve our sharks, called
SharkWater http://www.sharkwater.com/ .
This is a very powerful video. Check out the short clip and list of awards at the website.