Plates and GatesELF Activity: Geosphere 2A

http://andrill.org/education/elf_activities_2A.html

As part of NOAA Environmental Literacy Grant #NA09SEC490009 to the University of Nebraska–Lincoln's, ANDRILL Science Management Office.

This material is based on work supported by an Environmental Literacy Grant from the National Oceanic and Atmospheric Administration's Office of Education (NA0909SEC4690009) and prior work supported by the National Science Foundation under Grants ANT-0342484 and ESI-0632175. Any opinions, findings, and conclusions or recommendations expressed in these materials are those of the authors and do not necessarily reflect the views of the NOAA or the NSF.

The Current Location of Continents on the Earth Today

If these were pieces to a puzzle, can you see how they would fit together?

The Continents and the Plates They are Riding On

Notice that some plates are only ocean, while others have areas of ocean and land masses. Which plate do you live on?

Pangaea

This is how the continents were positioned 250 million years ago (mya). The supercontinent was called Pangaea.

Predict which regions were warmer 250 mya based on their location. Which ones were colder?

The land masses on Earth were not always in the same position as they

are now.

Approximate location of the Equator

It took approximately 180 million years for the plates to move from their position in Map 1 to Map 2.

1

2

Notice how Antarctica has broken away from South America and all the other continents, then moved south and become isolated.

How the Movement of the Earth’s Plates Affected Life in

the Oceans

There are over 300 species of octopuses and their range is worldwide. One question researchers ask is: How are octopus species related?

How the Movement of the Earth’s Plates Affected Life in

the Oceans?

We have seen that continental drift caused Antarctica to be separated from South America about 34 mya. The Drake Passage was formed, creating a cold oxygen-rich deep water environment. The fossil record shows new species of deep water octopus evolved about the same time. When similar species of octopus were found in deep waters in the Northern Hemisphere, researchers wondered where they came from. The activity explores where these deep water octopus originated and how they spread worldwide.

Close-up map of the Drake Passage showing the bathymetry (shape of the ocean floor) in this region. When the lines are very close, it indicates a steep drop. When the ‘gate’ opened up between Antarctica and South America, the waters from the Pacific could mix with the Atlantic. Species that were previously only in one ocean were now found in both.

Here you can see how the ocean current going around Antarctica keeps the water cold. Notice the swift drop in water temperature at the Polar Front. South of the Polar Front there is very little mixing of water from warmer latitudes; this is one reason Antarctica is so cold.

About 33-34 mya, Antarctica split off from South America, forming this deep cold channel. As the water became colder, it could hold more oxygen so organisms migrated deeper and deeper.

South North

As Antarctica became more isolated from the other continents, it became colder. The Antarctic Circumpolar Current surrounded the continent so the mixing with warmer waters from the north no longer occurred. As a result, ice sheets began to form. The plants could no longer live there and the animals either left, adapted to food from the sea, or became extinct.

The black line shows how much oxygen can be dissolved in water as the temperature increases. Notice that as the water gets warmer, the less oxygen it will hold. This means that the colder the water, the more oxygen it will hold.

As the colder waters around Antarctica began to hold more oxygen, octopus species began to migrate to the deeper levels and developed new species that could only live in the deeper regions.

(b) Example of deep water species that evolved about 34 mya as the Drake Passage was opening. The deep water species have a small, non-functioning ink sac.Shallow water species (a, c, d) found in various places around Antarctica contain a large, functioning ink sac.

As the colder waters around Antarctica began to hold more oxygen, octopus species began to migrate to the deeper levels and developed new species that could only live in the deeper regions.

Recently, Antarctic deep water octopus species were found to be related to similar deep water species in the Northern Hemisphere. How did they get there?

As the continents moved to their current position, ocean currents began to form. Cold, deep water from Antarctica is moved along the bottom of the ocean and surfaces near areas where warm water is being cooled. Follow the arrows in the map below to see where warm water near the Arctic is cooled, sinks, and forms a large conveyor belt of water throughout the Earth’s oceans.

With the development of the deep ocean conveyor belt, which picks up cold water in Antarctica, deep water octopus species were able to migrate to the Northern Hemisphere.

www.oceanservice.noaa.gov/education

Blue = deep cold waterRed = warmer surface water

This map shows the deep cold water species of octopuses that developed AFTER the Drake Passage opened and the waters became deep, cold, and oxygen-rich. The blue lines show the flow of deep cold water and you can see how they were able to migrate to other deep water areas around the world.

Cousins of the deep water octopus species which evolved in Antarctica are found in these areas. They are carried by this cold, deep ocean current.

Meet the scientist who gathered data and put this story together. Jan Strugnell with one of her octopus species. Want to read more about her?

Go to: http://www.antarctica.gov.au/science/meet-our-scientists/dr-jan-strugnell

This material is based on work supported by an Environmental Literacy Grant from the National Oceanic and Atmospheric

Administration’s Office of Education (NA09SEC4690009) and prior work supported by the National Science Foundation under Grants

ANT-0342484 and ESI-0632175. Any opinions, findings, and conclusions or recommendations expressed in these materials are those of the authors and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration or the National

Science Foundation.http://andrill.org/education/elf/activities