GSC 05.different

FOCUS

Biological communities at hydrothermal vents

GRADE LEVEL

5-6 (Life Science)

FOCUS QUESTION

What organisms are typical of hydrothermal vents

near the Galapagos Spreading Center?

LEARNING OBJECTIVES

Students will be able to identify and describe at

least three organisms that are typical of hydro-

thermal vent communities near the Galapagos

Spreading Center.

Students will be able to identify and discuss at

least three lines of evidence that suggested the

existence of hydrothermal vents before they were

actually discovered.

Students will be able to explain why hydrothermal

vent communities are apt to be short-lived.

MATERIALS

 A variety of art supplies, including construction

paper, markers, pipe cleaners, glue, tape, scis-

sors, etc.

 Copies of “Guidelines for Murals and Reports

on Hydrothermal Vent Organisms,” one copy

for each student or student group

AUDIO/VISUAL MATERIALS

None

TEACHING TIME

Four to five 45-minute class periods, plus time for

student research

SEATING ARRANGEMENT

Classroom style or groups of 3-4 students

MAXIMUM NUMBER OF STUDENTS

KEY WORDS

Hydrothermal vent

Galapagos Spreading Center

Mid-ocean ridge

Plate tectonics

BACKGROUND INFORMATION

On February 17, 1977, scientists exploring the

seafloor near the Galapagos Islands made one

of the most significant discoveries in modern sci-

ence: large numbers of animals that had never

been seen before were clustered around under-

water hot springs flowing from cracks in the lava

seafloor. Similar hot springs, known as hydrother-

mal vents, have since been discovered in many

other locations where underwater volcanic pro-

cesses are active.

These processes are often associated with move-

ment of the tectonic plates that make up the

Earth’s crust. The outer shell of the Earth (called

the lithosphere) consists of about a dozen large

plates of rock (called tectonic plates) that move

several centimeters per year relative to each

other. These plates consist of a crust about 5 km

2005 Galapagos Spreading Center

And Now for Something

Completely Different…

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

thick, and the upper 60 - 75 km of the Earth’s

mantle. The plates that make up the lithosphere

move on a hot flowing mantle layer called the

asthenosphere, which is several hundred kilome-

ters thick. Heat within the asthenosphere creates

convection currents (similar to the currents that

can be seen if food coloring is added to a heated

container of water). These convection currents

cause the tectonic plates to move. Where the

plates move apart, a rift is formed that allows

magma (molten rock) to escape from deep within

the Earth and harden into solid rock known as

basalt. Areas where this happens are known as

spreading centers, and are a well-known feature

of mid-ocean ridges (MORs) such as the East

Pacific Rise and Mid-Atlantic Ridge. Spreading

centers are also called “divergent plate bound-

aries,” because the plates are moving apart.

Convergent plate boundaries, on the other hand,

occur where tectonic motion causes plates to col-

lide. When one plate descends beneath the other,

the process is called subduction and high temper-

atures and pressures are generated that can lead

to explosive volcanic eruptions (such as the Mount

St. Helens eruption which resulted from subduc-

tion of the Juan de Fuca tectonic plate beneath

the North American tectonic plate). Transform

plate boundaries occur where plates slide hori-

zontally past each other. At these boundaries, the

motion of plates rubbing against each other sets

up huge stresses that can cause breaks (faults) in

the rock that can result in earthquakes. A well-

known example of a transform plate boundary is

the San Andreas fault in California.

Volcanic activity can also occur in the middle of a

tectonic plate, at areas known as hotspots, which

are thought to be natural pipelines to reservoirs

of magma in the upper portion of the Earth’s

mantle. The volcanic features at Yellowstone

National Park are the result of hotspots, as are

the Hawaiian Islands. As the Pacific tectonic

plate moves over the Hawaiian hotspot, magma

periodically erupts to form volcanoes that become

islands. The oldest island is Kure at the north-

western end of the archipelago. The youngest is

the Big Island of Hawaii at the southeastern end.

Loihi, east of the Big Island, is the newest volcano

in the chain and may eventually form another

island. As the Pacific plate moves to the north-

west, islands are carried farther away from the

hot spot, and the crust cools and subsides. At the

same time, erosion gradually shrinks the islands,

and unless there is further volcanic activity (or a

drop in sea level) the islands eventually submerge

below the ocean surface. To the northwest of

Kure, the Emperor Seamounts are the submerged

remains of former islands that are even older than

Kure.

The tectonic setting of the Galapagos Islands is

more complex. The Galapagos were also formed

by a hotspot called the Galapagos mantle plume

(GMP), which continues to produce active vol-

canoes (the Sierra Negra volcano erupted on

October 22, 2005). These islands are formed on

the Nazca Plate, which is moving east-southeast.

On the western side of the Nazca Plate, this

motion produces a divergent plate boundary with

the Pacific Plate. This boundary is called the East

Pacific Rise. On the northern side of the Nazca

Plate, just north of the Galapagos archipelago,

another divergent boundary exists with the Cocos

Plate. This boundary is known as the Galapagos

Spreading Center (GSC). A convergent bound-

ary exists on the eastern side of the Nazca Plate,

which is being subducted beneath the South

American and Caribbean Plates. This subduction

has caused some of the oldest seamounts formed

by the GMP to disappear beneath the South

American and Caribbean Plates, so it is not cer-

tain exactly how long the GMP has been active

in its present position (for illustrations of these

boundaries and plates, as well as detailed dis-

cussion of tectonic processes, see “This Dynamic

Earth” available online from the U.S. Geological

Survey at http://pubs.usgs.gov/publications/text/dynamic.pdf).

This tectonic setting means hydrothermal systems

along the GSC may receive magma from the

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

GMP as well as from rifts associated with the

spreading center itself. One of the key questions

about hydrothermal systems is how their biologi-

cal and geological processes are affected by vari-

ations in the supply of magma and thickness of

the Earth’s crust. Because the Galapagos mantle

plume is known to provide an increased supply

of magma to nearby hydrothermal vent systems,

the GSC is an ideal ”natural experiment” to study

this question. Ironically, despite the importance

of hydrothermal vents, the Galapagos Spreading

Center (GSC) where they were first discovered

has received very little exploration. This is the pri-

mary purpose of the 2005 Galapagos Spreading

Center Expedition.

In this lesson, students will learn about the first

exploration of hydrothermal vents, and investigate

some of the vent animals that had never been

seen before vent systems were discovered.

LEARNING PROCEDURE

1. To prepare for this lesson, review background

essays for the 2005 Galapagos Spreading

Center Expedition, the 2005 Galapagos

Rift Expedition, and the 2002 Ocean

Exploration Galapagos Rift Expedition (http://

oceanexplorer.noaa.gov/explorations/05galapagos/welcome.html;

http://oceanexplorer.noaa.gov/explorations/05galapagosrift/

welcome.html; and http://oceanexplorer.noaa.gov/

explorations/02galapagos/galapagos.html, respectively)

In addition, visit the Dive and Discover Web

site (http://www.divediscover.whoi.edu/expedition9/; linked

from the 2005 Rift Expedition Web page) for a

complete chronicle of the 2005 Galapagos Rift

Expedition, as well as the Dive and Discover

presentation on the 25th anniversary of the

discovery of hydrothermal vents (http://www.

divediscover.whoi.edu/ventcd/vent_discovery). You may also

want to obtain the CD-ROM of this presentation

or download selected images to accompany

your narrative about the discovery of hydrother-

mal vents in the following step.

2. Briefly review the concepts of plate tecton-

ics, being sure that students understand the

processes that take place at convergent and

divergent boundaries, why these boundaries

are often the site of volcanic activity, and the

distinction between volcanic activity at hotspots

and at plate boundaries. Hotspots are believed

to originate deep inside the Earth, far below

the tectonic plates that are floating on the asthe-

nosphere. Thus, hotspots are essentially station-

ary, while the plates are in constant motion; so

“chains” of islands and seamounts are formed

by hotspot lava as a plate moves over a hot-

spot location. Scientists have found that the dis-

tance between hotspots remains constant over

periods of time in which the distance between

features on tectonic plates changes by thou-

sands of kilometers. This observation provides

further evidence that hotspots are relatively

stationary.

Tell students that the idea of plate tectonics (like

many important scientific concepts) took a long

time to become accepted. The idea of conti-

nents moving across the surface of the Earth

was first suggested by Abraham Ortelius (a

Dutch mapmaker) in 1596, but it was not until

1912 that the idea was developed as an actual

scientific theory by a German meteorologist

named Alfred Wegener. Even then, the theory

was not generally accepted until the 1960’s

(see “This Dynamic Earth,” http://pubs.usgs.gov/

publications/text/dynamic.pdf for more details about the

history of plate tectonics theory).

Once accepted, plate tectonics theory helped

explain many different observations about

Earth’s biology, geography, and geology; but

also raised many new questions as well. One

of these concerned the possible existence of

hot springs in the deep ocean. The idea was

that lava erupting onto the seafloor at diver-

gent plate boundaries would cool and solidify

to form new crust. Because the cooling lava

would contract, cracks would be expected to

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

form in the solidified surface. Seawater enter-

ing these cracks could come into contact with

hot rocks below the seafloor where the water

would become heated and rise back to the

surface, possibly forming geysers or other fea-

tures similar to those seen on land (such as in

Yellowstone National Park).

While no one had actually seen a seafloor hot

spring, there were several pieces of evidence

that supported the idea:

• In certain parts of the Red Sea, deep waters

are known to have unusually high tempera-

tures, and abnormally high concentrations

of salt. Investigations of this phenomenon in

the 1960s found that seafloor sediments from

the same area were unusually rich in copper,

iron, manganese, zinc and other metals.

• Because the Red Sea has a mid-ocean ridge

running through it, scientists speculated that

hot brines and metal-rich sediments might be

related to the divergent plate boundary, and

that similar conditions might exist at other

spreading centers. Deep-sea drilling expedi-

tions to spreading centers in the Atlantic,

Pacific, and Indian Oceans found that sedi-

ments from these sites also contained high

concentrations of metals. In addition, metal-

rich sediments were also found on top of

volcanic ocean crust at sites far away from

active spreading centers, suggesting that

these deposits had been formed at mid-ocean

ridges and then transported away by seafloor

spreading.

• Deep-sea drilling expeditions also recovered

rocks from midocean ridge sites that were

different from the generally black rocks found

in the deep ocean. Analysis of minerals in

these unusual rocks suggested that they could

have been formed from typical black rocks by

chemical reactions that can only take place in

the presence of hot water.

• Plate tectonics theory led some scientists to

realize that large deposits of metal-rich ores

on land were pieces of the seafloor (called

ophiolites) that had been thrust on top of con-

tinents by collisions between tectonic plates.

The minerals in ophiolites were found to have

many similarities with the minerals found in

rocks near mid-ocean ridges.

• Scientists expected that the seafloor near

midocean ridges would be heated by hot

mantle material rising to the surface at diver-

gent plate boundaries. But measurements of

actual temperature in these areas were cooler

than expected. One of the proposed expla-

nations was that seawater entering cracks

in the seafloor could absorb heat and then

carry it away as the heated fluid rose back

to the seafloor surface and dispersed into the

ocean.

Seafloor hot springs offered an explanation

for many different observations; an important

characteristic of a good scientific theory. Since

the ultimate test of this theory was to find one

of these springs, a series of expeditions was

launched to study midocean ridges in greater

detail than had ever been attempted before.

For the first time, these expeditions made

extensive use of deep-diving submersibles.

Expeditions to the mid-Atlantic ridge made

many important observations, but did not find

a hot spring. Finally, in 1977, an expedition

studying the Galapagos Rift found an important

clue: an area of seafloor where the water tem-

perature was noticeably higher than normal,

and where the lava bottom was covered with

hundreds of clam and mussel shells. When sci-

entists descended onto the site in the submers-

ible Alvin, they saw shimmering water flowing

out of small cracks in the lava, then turning

cloudy as minerals began to precipitate out of

the warm fluid. The first hydrothermal vent had

been discovered.

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

But the biggest surprise was that the clams and

mussels were not alone: dense biological com-

munities that included crabs, octopi, bright red

tubeworms, and orange animals resembling

dandelions were found around the Galapagos

hydrothermal vents—and scientific ideas about

life on Earth were changed forever.

3. Tell students that they will be working in small

groups to create a class mural of a hydrother-

mal vent ecosystem. They will then prepare, as

a group, oral and written reports describing

the component of the class mural they created.

Students should be divided into one of the fol-

lowing groups:

• Tubeworms/Microbes

• Mussels/Clams

• Hydrothermal Vent Geology [focusing on the

physical structure of the vent(s) itself]

• Vent Shrimp/Dandelion Animals

• Octopi/Zoarcid Fish

Using the “Guidelines for Murals and Reports

on Hydrothermal Vent Organisms” worksheet,

guide students to use the Web sites referenced

in Step 1 and others that they may discover to

learn how to construct their group component

of the class mural and group reports.

4. Lead a discussion of students’ reports. The fol-

lowing points should be included:

• Often, mussels are among the first organisms

to colonize hydrothermal vent sites.

• Tubeworms can grow up to two meters long

and ten centimeters in diameter.

• Tubeworms obtain their nutrition from symbi-

otic bacteria that live inside the tubeworms.

The bacteria use carbon dioxide, hydrogen

sulfide, and oxygen to produce sugars that

the tubeworms use as food. The tubeworms

use their red plumes to extract hydrogen sul-

fide and oxygen from the surrounding water,

and make these chemicals available to the

symbiotic bacteria.

• Mussels obtain food from symbiotic microbes

living in their gills, as well as from food fil-

tered from the surrounding water

• Dandelion animals belong to the phylum

Cnidaria, which also includes jellyfish,

anemones, and corals. The “dandelions” are

actually colonies made of many individual

animals.

• Dandelion animals are scavengers, and are

among the last animals to colonize vent sites.

If there are a lot of dandelions around a vent

site, it usually means that the vents are no lon-

ger active and most of the other organisms in

the area are dying.

• Shrimp eat microbes and may also eat mus-

sels.

• Hydrothermal vent microbes include bacteria

and Archaea.

• Vent microbes are the base of the vent system

food chain.

• Vent microbes are chemoautotrophic, and are

the base of the vent system food chain.

• Vent microbes grow on every surface. Some

live inside tubeworms, clams, and mussels

and have symbiotic relationships with these

animals.

• Vent clams depend on symbiotic bacteria that

live in the their gills and produce sugars from

chemicals in the hydrothermal fluid.

•Octopi and zoarcid fish are top preda-

tors. Octopi eat crabs, clams, and mussels.

Zoarcid fish eat everything from tubeworms

to shrimp.

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

• Vent crabs include species like the Galatheid

crab (squat lobster) that are scavengers, as

well as species like the brachyuran crabs that

are fierce predators. Predatory crabs eat bac-

teria, shrimp, mussels, clams, tubeworms, and

other crabs.

• The Rose Garden was the hydrothermal

vent site where vent tubeworms were first

observed.

• Between 1977 and 2005, the Rose Garden

vanished, possibly due to a volcanic eruption

nearby.

THE BRIDGE CONNECTION

www.vims.edu/bridge – Select Ocean Science Topics,

then select Ecology, then Deep Sea

THE “ME” CONNECTION

Remind students that new scientific theories, and

sometimes actual discoveries, often are met with

skepticism before they are accepted; particularly

if they challenge a widely accepted belief or

theory. Have students write a brief essay in which

they discuss whether this a a good thing, or is an

obstacle to better understanding.

CONNECTIONS TO OTHER SUBJECTS

English/Language Arts; Physical Science;

Geography; Earth Science

EVALUATION

Class mural, reports and discussions in Steps 3

and 4 provide opportunities for assessment.

EXTENSIONS

Visit these sites for many more activities and links

related to plate tectonics, earthquakes and seis-

mology:

http://www.ldeo.columbia.edu/~mwest/WS4instructors/primer.html

RESOURCES

http://oceanexplorer.noaa.gov/explorations/05galapagos/welcome.html

– Web page for the 2005 Galapagos

Spreading Center Expedition

http://www.divediscover.whoi.edu/ventcd/vent_discovery – Dive

and Discover presentation on the 25th anni-

versary of the discovery of hydrothermal vents

http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/ps_vents.html

– Article, “Creatures of the Thermal Vents”

by Dawn Stover

http://www.oceansonline.com/hydrothe.htm – “Black Smokers

and Giant Worms,” article on hydrothermal

vent organisms

Tunnicliffe, V., 1992. Hydrothermal-vent communi-

ties of the deep sea. American Scientist 80:

336-349.

Corliss, J. B., J. Dymond, L.I. Gordon, J.M.

Edmond, R.P. von Herzen, R.D. Ballard,

K. Green, D. Williams, A. Bainbridge, K.

Crane, and T.H. Andel, 1979. Submarine

thermal springs on the Galapagos Rift.

Science 203:1073-1083. – Scientific jour-

nal article describing the first submersible

visit to a hydrothermal vent community

NATIONAL SCIENCE EDUCATION STANDARDS

Content Standard A: Science As Inquiry

• Abilities necessary to do scientific inquiry

• Understandings about scientific inquiry

Content Standard B: Physical Science

• Properties and changes of properties in matter

• Transfer of energy

Content Standard C: Life Science

• Structure and function in living systems

• Populations and ecosystems

• Diversity and adaptations of organisms

Content Standard D: Earth and Space Science

• Structure of the Earth system

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

Content Standard E: Science and Technology

• Abilities of technological design

• Understandings about science and technology

Content Standard F: Science in Personal and Social

Perspectives

• Populations, resources, and environments

• Science and technology in society

Content Standard G: History and Nature of Science

• Science as a human endeavor

• Nature of science

FOR MORE INFORMATION

Paula Keener-Chavis, Director, Education Programs

NOAA Office of Ocean Exploration

Hollings Marine Laboratory

331 Fort Johnson Road, Charleston SC 29412

843.762.8818

843.762.8737 (fax)

[email protected]

ACKNOWLEDGEMENTS

This lesson plan was produced by Mel Goodwin,

PhD, The Harmony Project, Charleston, SC

for the National Oceanic and Atmospheric

Administration. If reproducing this lesson, please

cite NOAA as the source, and provide the follow-

ing URL: http://oceanexplorer.noaa.gov

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

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2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

Student Handout

Guidelines for Murals and Reports on Hydrothermal Vent Organisms

1. Which group of animals is often the first to colonize a hydrothermal vent site?

2. How big do tubeworms grow?

3. How do tubeworms obtain their food? What are their red plumes for?

4. How do mussels obtain their food?

5. What phylum includes the “dandelion animals?”

6. What do “dandelion animals” eat? What do large numbers of “dandelion animals” usually indicate

about a biological community near a hydrothermal vent?

7. How do vent shrimp obtain their food?

8. What kinds of microbes are found at hydrothermal vents? Where are they in hydrothermal vent food

chains? How do they obtain their food?

9. Where do vent microbes grow?

10. How do vent clams obtain their food?

11. Where are octopi and zoarcid fish in hydrothermal vent food chains? What do they eat?

12. How do vent crabs obtain their food?

13. What is the Rose Garden?

14. What happened to the Rose Garden between 1977 and 2005?

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

Teacher Answers

Guidelines for Murals and Reports on Hydrothermal Vent Organisms

1. Which group of animals is often the first to colonize a hydrothermal vent site?

• Often, mussels are among the first organisms to colonize hydrothermal vent sites.

2. How big do tubeworms grow?

• Tubeworms can grow up to two meters long and ten centimeters in diameter.

3. How do tubeworms obtain their food? What are their red plumes for?

• Tubeworms obtain their nutrition from symbiotic bacteria that live inside the tubeworms. The bacteria

use carbon dioxide, hydrogen sulfide, and oxygen to produce sugars that the tubeworms use as

food. The tubeworms use their red plumes to extract hydrogen sulfide and oxygen from the surround-

ing water, and make these chemicals available to the symbiotic bacteria.

4. How do mussels obtain their food?

• Mussels obtain food from symbiotic microbes living in their gills, as well as from food filtered from

the surrounding water

5. What phylum includes the “dandelion animals?”

• Dandelion animals belong to the phylum Cnidaria, which also includes jellyfish, anemones, and cor-

als. The “dandelions” are actually colonies made of many individual animals.

6. What do “dandelion animals” eat? What do large numbers of “dandelion animals” usually indicate

about a biological community near a hydrothermal vent?

• Dandelion animals are scavengers, and are among the last animals to colonize vent sites. If there

are a lot of dandelions around a vent site, it usually means that the vents are no longer active and

most of the other organisms in the area are dying.

7. How do vent shrimp obtain their food?

• Shrimp eat microbes and may also eat mussels.

8. What kinds of microbes are found at hydrothermal vents? Where are they in hydrothermal vent food

chains? How do they obtain their food?

• Hydrothermal vent microbes include bacteria and Archaea.

• Vent microbes are the base of the vent system food chain.

• Vent microbes are chemo-autotrophic, and are the base of the vent system food chain.

9. Where do vent microbes grow?

• Vent microbes grow on every surface. Some live inside tubeworms, clams, and mussels and have

symbiotic relationships with these animals.

10. How do vent clams obtain their food?

• Vent clams depend on symbiotic bacteria that live in the their gills and produce sugars from chemi-

cals in the hydrothermal fluid.

oceanexplorer.noaa.gov

2005 Galapagos Spreading Center Expedition – Grades 5-6 (Life Science)

Focus: Biological communities at hydrothermal vents

Teacher Answers (Continued)

11. Where are octopi and zoarcid fish in hydrothermal vent food chains? What do they eat?

• Octopi and zoarcid fish are top predators. Octopi eat crabs, clams, and mussels. Zoarcid fish eat

everything from tubeworms to shrimp.

12. How do vent crabs obtain their food?

• Vent crabs include species like the Galatheid crab (squat lobster) that are scavengers, as well as

species like the brachyuran crabs that are fierce predators. Predatory crabs eat bacteria, shrimp,

mussels, clams, tubeworms, and other crabs.

13. What is the Rose Garden?

• The Rose Garden was the hydrothermal vent site where vent tubeworms were first observed

14. What happened to the Rose Garden between 1977 and 2005?

• Between 1977 and 2005, the Rose Garden vanished, possibly due to a volcanic eruption nearby