Lesson Plan - SHACC · 2020. 9. 22. · nomes provide insights into elasmobranch evolution and the origin of vertebrates. Nature Ecology & Evolu- tion, 2(11), 1761–1771. doi: 10.1038/s41559

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Title: “Shark Evolution and Conservation” Connections

Surfers share the water with

Focus Question When did sharks first appear on Earth and why are they important to marine ecosystems today?

Objectives/Outcomes Students will be able to: Graph the lengths of various large sharks and compare them to

Megalodon Understand how to use a phylogenetic tree Understand the importance of sharks in a marine ecosystem

Key Terms Apex predator, ecosystem, chondrichthy, food web, conservation,

phylogenetic tree

Outline Discuss the Focus Question with class: “When did sharks first appear on Earth and why are they important to marine ecosystems today?

Next show them the video “Why Sharks Matter” (about 4 minutes) https://www.youtube.com/watch?time_continue=84&v=DvRN3a3j5xQ

Students will break into groups of 2 (or some can work alone) to work on the student handout and the graph. (You will also have to provide Students Handout with background information)

To wrap up the lesson, come back and have students answer the Focus Question one more time and have students brainstorm and/or shark what they wrote for the “Reflection” on the handout.

Assessment 1. Student engagement and participation.

2. Completion of worksheet: “SHARK EVOLUTION AND CONSERVATION”

Topics Shark Evolution, Apex Predators and Conservation

Grades 6-8

Duration 60 minutes

Materials Pencil or pen, ruler Chromebook Google Sheets Internet access Student handouts

Standards NGSS

MS-LS4-2 MS-ESS3-3

Practices: Engaging in Argument

from Evidence Analyzing and Inter-

preting Data Crosscutting Concepts:

Cause and Effect Stability and Change

Core Ideas: LS4.A: Evidence of Com-

mon Ancestry and Diver-sity

ESS3.C: Human Impacts on Earth Systems

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GUIDED INSTRUTION: PROCEDURE:

1. Discuss the Focus Question. Record responses or have students write down the question and responses in their notebook (Interactive Science Notebook or Logbook). You will come back to this at the end of the lesson and record their thoughtful answers.

2. Have students discuss with their “elbow partners” about what they think of sharks.

3. Have students “popcorn” read and annotate the “Background” information.

4. Next show them the video (about 4 minutes) https://www.youtube.com/watch?time_continue=84&v=DvRN3a3j5xQ

(File:Megalodon-Carcharodon-Scale-Chart-SVG.svg. (n.d.). Retrieved October 21, 2019, from https://commons.wikimedia.org/wiki/File:Megalodon-Carcharodon-Scale-Chart-SVG.svg.)

5. Students will break into groups of 2 or some can work alone to work on the student handout and the graph.

6. Students will need to have access to the internet to research the lengths of the 5 large sharks they choose to compare to Megalodon. Be sure to either use the metric system or standard measurement units.

7. You will need to set up Google Classroom if you would like students to turn in their graphs digitally or have them “share” it with you. You may want to modify this and have them create the graph by hand. You will need graph paper if you choose to make this modifi-cation.

8. Students will need to create a new Google Sheets document in order to create a bar graph. Make sure to remind them to title the document with their name and their partner’s name.

9. To wrap up the lesson, come back to the Focus Question and have them answer the question.

10. Then have students brainstorm and/or shark what they wrote for the “Reflection” on the handout.

Materials Pencil or pen, ruler Chromebook Google Sheets Internet access Student handout

NGSS MS-LS4-2: Apply scientific ideas to construct an explanation for anatomi-cal similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships MS-ESS3-3: Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment Practices Analyzing and Interpreting Data Engaging in Argument from Evidence Core Ideas LS4.A: Evidence of Common Ancestry and Diversity ESS3.C: Human Impacts on Earth Sys-tems Crosscutting Concepts Patterns, Cause and Effect, Stability and Change

EXTENSIONS:

Create an Infographic for a favorite shark

Research and create a PowerPoint presentation on a favorite shark

Create a video to help save the sharks

Watch the documentary “Sharkwater” or “Sharkwater Extinction” by Rob Stewart. Here is the link to the website for worksheets and more background information.

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https://www.sharkwater.com/downloads/SharkwaterExtinction_Educators_Guide_2018.pdfhttps://shacc.org/host-an-event/

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RESOURCES:

Estes, J. A., Terborgh, J., Brashares, J. S., Power, M. E., Berger, J., Bond, W. J., … Wardle, D. A. (2011). Trophic Downgrading of Planet Earth. Science, 333(6040), 301–306. Retrieved from https://science.sciencemag.org/content/333/6040/301.full

File:Megalodon-Carcharodon-Scale-Chart-SVG.svg. (n.d.). Retrieved October 21, 2019, from https://commons.wikimedia.org/wiki/File:Megalodon-Carcharodon-Scale-Chart-SVG.svg.

Hara, Y., Yamaguchi, K., Onimaru, K., Kadota, M., Koyanagi, M., Keeley, S. D., … Kuraku, S. (2018). Shark ge-nomes provide insights into elasmobranch evolution and the origin of vertebrates. Nature Ecology & Evolu-tion, 2(11), 1761–1771. doi: 10.1038/s41559-018-0673-5

Long, J. A., Burrow, C. J., Ginter, M., Maisey, J. G., Trinajstic, K. M., Coates, M. I., … Senden, T. J. (2015). Correc-tion: First Shark from the Late Devonian (Frasnian) Gogo Formation, Western Australia Sheds New Light on the Development of Tessellated Calcified Cartilage. Plos One, 10(6): e0131502. doi: 10.1371/journal.pone.0131502

Martinez-Perez, C., Martin-Lazaro, A., Ferron, H. G., Kirstein, M., Donoghue, P. C. J., & Botella, H. (2018). Vas-cular structure of the earliest shark teeth. Acta Geologica Polonica, 68(3), 457–465. Retrieved from https://geojournals.pgi.gov.pl/agp/article/view/26058

Myers, R. A., Baum, J. K., Shepherd, T. D., Powers, S. P., & Peterson, C. H. (2007). Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean. Science, 315(5820), 1846–1850. doi: 10.1126/science.1138657

Pimiento, C., Ehret, D. J., Macfadden, B. J., & Hubbell, G. (2010). Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama. PLoS ONE, 5(5): e10552. doi: 10.1371/journal.pone.0010552

Pimiento, C., & Clements, C. F. (2014). When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record. PLoS ONE, 9(10): e111086. doi: 10.1371/journal.pone.0111086

Raup, D. M., & Sepkoski, J. J. (1982). Mass Extinctions in the Marine Fossil Record. Science, 215(4539), 1501–1503. doi: 10.1126/science.215.4539.1501

Stevens, J., Bonfil, R., Dulvy, N. K., & Walker, P. A. (2000). The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems. ICES Journal of Marine Science, 57(3), 476–494. doi: 10.1006/jmsc.2000.0724

Teen Kids News. (2017, August 31). Why Healthy Oceans Need Sharks? Retrieved October 21, 2019, from https://teenkidsnews.com/tkn-news/science/why-healthy-oceans-need-sharks/.

Turner, S., & Miller, R. (2005). New Ideas About Old Sharks. American Scientist, 93(3), 244-252. doi: 10.1511/2005.53.965

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Shark Evolution and Conservation Activity (STUDDENT HANDOUT)

BACKGROUND:

Sharks have a cartilaginous skeleton and belong to the Chondrichthyes phylum. Their ancestors first evolved around 450 million years ago (Hara et al., 2018). According to fossil records, modern cartilaginous fishes, like sharks, derived from jawless fishes or agnathans (Turner & Miller, 2005). Today, there are approximately 830 species of Chondrichthyes, which also include skates and rays (Turner & Miller, 2005). Chondrichthyes have survived five mass extinctions (Raup & Sepkoski, 1982). The evolution of jaws enabled fish to grasp live prey and even cut or chew for easier digestion. It is thought that this useful adaptation increased the evolutionary opportunities for early fishes and particularly sharks, thus helping them to survive the harsh marine ecosystem (Turner & Miller, 2005). As jaws evolved so have teeth. Most sharks’ teeth continuously replace themselves throughout their lifetime, leaving behind an abundance of fossil records (Martinez-Perez et al., 2018). Because sharks’ skeletons are made of cartilage there are very few fossils other than teeth for paleontologists to study.

Based mostly on an abundance of dental fossil records, Carcharocles megalodon (“Megalodon”) is confirmed to be the largest shark to have ever lived on Earth. According to Megalodon’s tooth height, it reached a total length of about 14.2-16m or about 50 feet (Pimiento et al., 2010). Megalodon was also an apex predator that fed on marine mammals, such as cetaceans (whales and dolphins). It lived on Earth from 15.9-2.6 million years ago (Pimiento & Clements, 2014). Apex predators feed at the top of the food web and usually do not have predators of their own. They are often large-bodied vertebrates with large habitat ranges. These apex predators, such as the Megalodon and today’s large sharks, are important for maintaining stability within an ecosystem. If apex predators disappear, they can produce negative effects throughout the marine food web (Myers et al., 2007).

Today, humans are having an impact on apex predators by overfishing and therefore are negatively impacting food webs. This impact of removing apex predators is called “top-down” impacts or “trophic cascades” as trophic pyramids (organized food webs) are altered affecting all aspects of the ecosystem (Estes et al., 2011). Over the past 35 years, 11 large shark populations decreased therefore having extreme effects on the marine ecosystem which they live in, such as the northwest Atlantic ocean ecosystems. Because large sharks prey on rays, skates, and small sharks (elasmobranchs), an abundance of cownose rays in the northwest Atlantic ocean easily destroyed the local scallops in that area (Myers et al., 2007). Examples like this is evidence that sharks are important for a healthy marine ecosystem.

Sharks have stood the test of time and survived five major extinctions, but today their populations are declining at an alarming rate and quickly altering marine ecosystems. It is important that research continues to be done on the importance of apex predators and the need to protect them. Internationally, restrictions need to be made and enforced in order to have sustainable and healthy marine ecosystems that will remain balanced for years to come.

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(STUDDENT HANDOUT)

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(STUDDENT HANDOUT)

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Figure 1. Phylogenetic Tree. Fossil discoveries in the deep geological record show that the early fishes

diversified during the Ordovician period into several major groups, many of which went extinct by the end of

the Devonian (Turner & Miller, 2005).


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Name:______________________________________________ Period:_________ Date:__________________

SHARK EVOLUTION AND CONSERVATION

Directions: Using the Background information and the Phylogenetic Tree answer the following questions. Once you have answered the questions, create a graph of your own comparing Megalodon length with 5 other large sharks, such as the basking shark, great white, bull shark, tiger shark, mako shark, goblin shark, greenland shark, and great hammerhead shark. . 1. When did sharks first appear on Earth? _______________________________________________________ 2. What group of fish did they evolve from? _____________________________________________________ 3. What is the shark’s skeleton made out of? ____________________________________________________ 4. When did Megalodon first appear on Earth and when did he go extinct? ____________________________ ________________________________________________________________________________________ 5. How long was Megalodon? ________________________________________________________________ 6. What is an apex predator? Give an example.___________________________________________________ ________________________________________________________________________________________ 7. Why are apex predators important to an ecosystem?____________________________________________ _________________________________________________________________________________________ 8. Looking at the phylogenetic tree, when did chondrichthyans (sharks) first appear on Earth? _________________________________________________________________________________________ 9. When did tetrapods (humans) first appear on Earth? ____________________________________________ _________________________________________________________________________________________ 10.What fish did tetrapods (humans) evolve from?________________________________________________

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11. Now that you know the length of Megalodon, research the length of 5 large sharks. (Below is a list to choose from.) Using Google Sheets, create a bar graph comparing the modern day sharks to the prehistoric Megalodon. Don’t forget to give your graph a title, label the x and y axis and create a key. Use Google Classroom to turn in your graph. Large sharks to choose from, but only choose 5 for your graph:

bull shark

tiger shark basking shark

whale shark great white mako shark

goblin shark greenland shark

great hammerhead shark

blacktip reef shark thresher shark

Using the internet find the lengths of your 5 sharks. Use this data to create your graph. Reflection: Why are sharks important and what can we do to help save them? ___________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________ ___________________________________________________________________________________________________________

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KEY: SHARK EVOLUTION AND CONSERVATION 1. When did sharks first appear on Earth? 450 MILLION YEARS AGO 2. What group of fish did they evolve from? JAWLESS FISH OR HAGFISH 3. What is the shark’s skeleton made out of? CARTILAGE 4. When did Megalodon first appear on Earth and when did he go extinct? FIRST APPEARED 15.9 MYA AND WENT EXTINCT 2.6 MYA 5. How long was Megalodon? ABOUT 14.2-16M OR OVER 50 FEET LONG 6. What is an apex predator? Give an example AN APEX PREDETOR EATS AT THE TOP OF THE FOOD WEB AND DOES NOT USUALLY HAVE PREDATORS 7. Why are apex predators important to an ecosystem? THEY KEEP THE FOOD WEB BALANCED AND THE ECOSYSTEM HEALTHY 8. Looking at the phylogenetic tree, when did chondrichthyans (sharks) first appear on Earth? ABOUT 450 YEARS AGO, AT THE END OF THE ORDOVICIAN PERIOD 9. When did tetrapods (humans) first appear on Earth? ABOUT 400 MYA OR IN THE MIDDLE OF THE DE-VONIAN PERIOD 10. What fish did tetrapods (humans) evolve from? SARCOPTERYGIANS

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Lesson Plan - SHACC · 2020. 9. 22. · nomes provide insights into elasmobranch evolution and the origin of vertebrates. Nature Ecology & Evolu- tion, 2(11), 1761–1771. doi: 10.1038/s41559