In the deep, cold, and dark open oceans of the world, a diverse group of fishes and other animals aggregate. These animals are strange looking- the fish are small, with big sharp teeth, and have lures and small spots on their bodies that produce light, there are bright-red shrimp-like animals, and many different kinds of jellies. These animals live in this seemingly inhospitable environment so that they can hide in the darkness from their predators. For the fish, these predators include sharks, tunas, and dolphins- animals we would worry about if they were to lose a major source of food. The depth of this midwater layer can change with location, time of day, time of year, and other factors, but is typically around 200-1000 meters (~600-3000 feet), in the layer of the ocean called the mesopelagic zone, also referred to as “the twilight zone.” Spanning all of the oceans (except for very close to the coasts) this region harbors a huge diversity and abundance of animals. This 5 day unit introduces students to methods that marine scientists use to study the mesopelagic zone, what the environment is like, who lives there, how they are affected by human activities and why it is important for people to understand these things.

  • Students graph and visualize authentic data to model how water column properties (temperature, oxygen, chlorophyll, nutrient levels) change with depth.
  • Students construct mesopelagic research plans employing current sampling techniques and technologies to collect data to respond to student-generated questions.
  • Students observe and analyze specimens (or photographs) of deep sea animals to compare and contrast characteristic features.
  • Students investigate the importance of oceans and anthropogenic impacts in the deep sea to design solutions for threats to the health of deep sea environments.
  • Students act as fishery resource managers to analyze needs from various stakeholders in a simulation to make data-based decisions that incorporate ecosystem health and economic interests.
  • The ocean environment is the same at all depths.
  • There are no or few animals living in the deep open ocean.
  • Most animals in the oceans live close to the surface.
  • All fish are big.
  • The oceans are well-studied; there are few unanswered questions related to the oceans.
  • Ecosystems and fisheries are not linked by individual species.
  • The deep sea is so far removed from human impacts that we do not negatively affect deep sea environments.
  • There are 5 lessons in this unit. Each lesson includes a PowerPoint presentation and an activity. Students will plot oceanographic data (lesson 1), design their own deep sea research plans (lesson 2), make observations of mesopelagic animals (lesson 3), develop solutions for human impacts in the deep sea (lesson 4), and run simulations of ecosystem based management techniques (lesson 5).
  • This lesson provides an overview of the physical properties of the ocean that change with depth as well as the tools that are used for sampling these properties. Material presented includes: (1) What a CTD is and how it is used to sample water column properties, (2) temperature decreases with depth (students draw on prior knowledge that cold water sinks, and warm rises), (3) oxygen decreases with depth as a result of both physical and biological forcings, and (4) nutrient concentrations increase with depth because they are used up by photosynthetic organisms near the surface and released at depth as waste. After the presentation, students plot data and answer questions provided on a handout.
  • Activity: plot data, interpret, and answer questions.
  • This presentation explains the different methods that are used to study mesopelagic animals and includes: (1) Nets, which are relatively low cost and simple to deploy, but generally kill the animals that they collect, so are not good for observing live animals, (2) Fishfinders (i.e., SONAR) use soundwaves to survey the water column; they allow scientists to survey a large region of the ocean while conducting other scientific activities, but do not provide explicit information on which animals are detected, (3) Remotely operated vehicles allow for direct observations (with video) of the mesopelagic zone and collection of live animals, but only survey a very small volume of water. Operating an ROV is very expensive, (4) Submarines actually bring scientists into the environment, providing them direct observations of the mesopelagic zone. They are also very expensive to operate, and can be risky to humans.
  • Activity: pose a scientific question about the mesopelagic zone and design a research plan to answer the question.
  • This lesson introduces some of the key adaptations that mesopelagic animals have for living in the deep open ocean. These include: (1) Large mouths in order to effectively catch what little prey is available, (2) the ability to produce light and (3) camouflaging by being transparent, black, red or silver.
  • The lesson is followed by an activity in which students look at images of different mesopelagic animals and observe the different adaptations.
  • Human activity has an important impact on all submarine environments, including the mesopelagic zone. This lesson introduces students to the different impacts that humans have on deep sea environments, challenging them to connect the link between human actions on land to remote deep-sea environments. The deep sea is hard to see and study, and therefore commonly overlooked or ignored, but is increasingly impacted negatively by human actions. The students are further called upon to develop their own creative solutions to address human impacts in the deep sea.
  • Activity: summarize the main human impacts in the deep sea, and propose solutions to some of these.
  • Activity: role play as marine resource manager and make management decisions in a simulation.
  • These lessons were developed for a 9th grade Earth Science class. Each paired lesson and activity were designed for a 90 minute long class. There are no necessary prerequisites. This lesson would most appropriately be taught within a larger unit on oceans.
  • Each lesson has an accompanying activity that is required for evaluation:
          Lesson 1: Students plot real oceanographic data and answer questions based
          on these data.
          Lesson 2: Students develop their own deep sea research plans using the currently
          available technologies for studying mesopelagic animals, and requiring realistic time
          and funding goals.
          Lesson 3: Students observe mesopelagic animals, and elucidate special
          adaptations for mesopelagic living.
          Lesson 4: Students develop solutions for human impacts in the deep sea.
          Lesson 5: Students run through simulations of ecosystem based management
          techniques. This activity requires synthesizing all of the information learned in
          the first 4 lessons.
  • The instructor should review and evaluate all of these activities for demonstration that students have adequately understood the material presented. Alternatively, students can review and critique each other’s work. This may be particularly useful for Lessons 2 and 4, which require creative approaches.
  • 5. Heating of Earth's surface and atmosphere by the sun drives convection within the atmosphere and oceans, producing winds and ocean currents.
          d. properties of ocean water such as temperature and salinity can be used to explain the
          layered structure of the oceans, generation of horizontal and vertical ocean currents, and
          the geographic distribution of marine organisms.
  • 6. Climate is the long term average of a region's weather and depends on many factors.
          d. use of computer models to predict the effects of increasing greenhouse gases on
          climate for the planet as a whole and for specific regions.
  • 7. Each element on Earth moves among reservoirs in the solid Earth, oceans, atmosphere, and organisms as part of biogeochemical cycles.
          b. the global carbon cycle in terms of the different physical and chemical forms of
          carbon in the atmosphere, oceans, biomass, and fossil fuels, and the movement of carbon
          among these reservoirs.
  • 9. The geology of California underlies the state's wealth of natural resources as well as its natural hazards.
          a. the resources of major economic importance in California and their relation to
          California's geology.
  • HS-ESS2-5. Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.
  • HS-ESS2-7. Construct an argument based on evidence about the simultaneous coevolution of Earth’s systems and life on Earth.
  • HS-ESS3-1. Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity.
  • HS-ESS3-3. Create a computational simulation to illustrate the relationships among management of natural resources, the sustainability of human populations, and biodiversity.
  • HS-ESS3-4. Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.

Photo Credit: Understanding Evolution

Photo Credit: PEW Charitable Trusts

Photo Credit: Amanda Netburn
Lesson Specifics
  • Grade Level: 9th grade Earth Science class
  • Time Frame: 5 lessons: each paired lesson and activity are designed for a 90 minute long class

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