Script for
Oceans Life - Past and Present

This slideshow is designed for upper primary, but can be used with multiple age groups including adults.  It is an attempt to provide background information on climate change and how important oceans are to the overall driver of climate on the surface of the Earth.

Slide 1.  Ocean Life – Past and Present

On the animation the blue are cold surface currents and the red is warm surface currents.  Point out that the currents are different as you go down with depth.  This presentation looks at present day marine life and see what clues we can find from marine fossils.  We can tell changes of climate through time because of the fossils.


is the scientific study of the ocean. Traditionally, the Earth has been viewed from land. However, if you look at the Earth from outer space, the oceans comprise 71% of the Earth’s surfaces. The continents are really only the tops of high mountains from the ocean bottom. Oceanography is concerned with studying the biology, geology, chemistry, and physics of the oceans.

The oceans have evolved distinct features that are unique among the other planets in the Solar System. The oceans harbor entire populations of organisms that use the marine environment to their benefit. The oceans also provide humans with valuable nutrition, transportation, and weather. Many organisms originated in the sea. The marine environments are more stable by continuously supplying the needs of organisms than the unforgiving land environments.

Marine water has many elements and compounds dissolved, creating the term “salt” water (including Na, Cl, Mg, C, P).   There are also other components like silicic acid that are important to creating shells.  Humans and most organisms require fresh water to survive.  Most organisms on land require oxygen.  Marine animals also require oxygen, which is dissolved in water.

The interaction of the oceans and atmosphere creates our weather.   

Slide 2.   Why are oceans important? 

We need to look at present oceans.  The surface of the water has dissolved gases so available to organisms including oxygen and carbon dioxide.  Fish have developed gills that allow them to capture oxygen from the water.   Although water is H2O, organisms cannot take the oxygen out of water. 

In this picture carbon dioxide is seeping from the ocean floor near Ischia, Italy from volcanic activity.  It becomes dissolved within the marine water.  Marine plants, both large and small can take this carbon dioxide and use it in their photosynthetic process. 

Oceans are important because they create currents, on the surface and with depth.  The difference of warm water and cold water; density (caused by dilution of a normal 35 parts per million).  Oceans also maintain cold and heat slower than land.  The interaction causes weather patterns.  Also just the fact that the earth rotates causes what is called the Coriolis effect (a deflection to the right in the Northern Hemisphere and left in Southern Hemisphere)

Over time this would affect the biological life.  The clues they leave through time are fossils.  The information tells a story of climate change through time.

Picture information: Volcanic carbon dioxide seeps from the ocean floor near Ischia, Italy. (Image credit: Pasquale Vassallo, Stazione Zoologica Anton Dohrn)

Slide 3.   Land and Water

Compare land with water on the surface of the Earth.  There is about 71% of the surface that is water (both marine and fresh).  Look at the position of land vs water.  If you compare northern and southern hemisphere there is a pattern.  North and South America (land and land); Europe and Africa (land and land); Atlantic (ocean and ocean); Pacific  (ocean and ocean); but India Ocean and Asia (ocean and land).  The difference in cooling and warming of water and land, makes this area the origin of most weather patterns and then goes east.  Rotation of the Earth (Coriolis Effect) creates this dynamic system.

Slide 4.  Water Masses with Depth

Atmosphere and Oceans as they interact together are basis of our weather.

Temperature and density can define a water or atmospheric mass.  Different organisms live in different water masses.  Cold water organisms will not be abundant in warm water.

Slide 5.  World Wide Circulation

In the oceans warmer water can hold more salt, and colder water holds less salt. Salt water is more dense than fresh water of the same temperature. The salt water will layer itself below the fresh water. Warm water is less dense than cold water. So cold water will layer under warm water. Add the combination of different amounts of salt and different temperature and you have a layering effect in the water column. The world’s oceans are a three-dimensional nightmare of layers of different water masses that can move in different directions.

Bottom topography can act as a barrier to water masses already in motion. If a cold saline water mass is moving along the bottom and "hits" a mountain it would be forced upwards. This is one form of upwelling. This would displace the water masses above it, causing lots of movement.   The entire cycle can take 1000 years to complete.

Slide 6.   Present Day Carbon Cycle

The Earth is a dynamic system.  Interaction of land, sea, and air causes changes of certain molecules.  Carbon is one of those.

Carbon is also present in the Earth's atmosphere, soils, oceans, and crust.  When viewing the Earth as a system, these components can be referred to as carbon  pools (sometimes also called stocks or reservoirs) because they act as storage houses for large amounts of carbon.  Any movement of carbon between these reservoirs is called a flux.  In any integrated system, fluxes connect reservoirs together to create cycles and feedbacks

Carbon cycle takes into account biological activity on earth including humans.  Through time it has changed.  Fossils give an insight of the earth’s former concentration and distribution of organisms.

At the sir-sea boundary, atmospheric CO2 is dissolved in water.  Near surface, many photosynthetic plankton convert the dissolved CO2  into organic carbon.  In addition, waster and Co2 molecules react to form carbonate ions  (HCO3’).  Carbonate ions are used by many marine organisms to form calcium carbonate shells.  As these marine organisms die, the resulting debris falls from the near the surface into deeper water.  This sedimentation increases adsorption of carbon from the atmosphere by removing carbon from surface waters.  The rate of carbon movement to the deep ocean also depends on a circulation pattern called the ocean conveyor belt. 

Slide 7.  Important  gases through Time

Different organisms produce different gases.  When plants became abundant they released more oxygen then they consumed.  The oxygen we have in the air today is because of plants over time. Not only land plants, but water plants. Gases in the Earth’s atmosphere has changed through time.  Biological life has influence the atmosphere, but the atmosphere has influenced the evolution of organisms on Earth.  Gases in the atmosphere influence what ions are available in the water.  Some of the gases can interact with organisms to evolve shell making. The atmosphere is similar to the oceans in that air masses can move from one part of the earth to another bases on temperature and pressure.

Air takes up space and has weight. It is made of a mixture of different gases which changes with altitude. At the surface of the Earth, air is a mixture of the gases including nitrogen, oxygen, argon, carbon dioxide, hydrogen, and various other rare gases. The percentage of carbon dioxide varies slightly depending on the presence of vegetation. There are also traces of ammonia, hydrogen sulfide, oxides, sulfur dioxide, and other gases. The percentage of dry air varies little at different locations on the Earth's surface.However, as you travel upward in the atmosphere the percentage of the gases changes. At 800 km there is only hydrogen and helium in about equal proportions

Slide 8. Six Kingdoms

Of the 6 Kingdoms most have representatives that live in the ocean.  Some like fungi are rare, but others like lower Animalia are very common. Present day organisms help understand past organisms and the number of calcareous organisms help scientists interpret the elements in past oceans.

many cells working together
mainly marine
calcareous, siliceous, spongin
lives in clean, medium to deep water

Includes jellyfish, corals, sea anenomes
lives near shore to deep marine
have tentacles with stinging cells (nematocysts)
calcareous outer skeletons (corals)

Includes insects, crabs, shrimp
segmented with appendages
has an exoskeleton (protection on outside)
made of chitin or calcareous

includes abalone, bivalves, gastropods
soft bodied animals
make a shell of calcium carbonate
lives in mud, sandy, forests, soil, rivers, lake, and marine

includes sand dollar, sea star, sea urchin
5 part “star” symmetry
spicules and plates made of calcium carbonate

abundant in ancient oceans
calcareous shells
lophotrochozoan organisms

Abundant in ancient oceans
calcareous shells
lophotrochozoan organisms

 Slide 9.  Organisms in ocean take up these ions   Bone versus shell

Organisms in the ocean take up ions and incorporate them into their existence.  Shells usually are for protection, while bones are usually part of the living organism’s metabolic stability.   The two pictures show the difference between the make up of shell and bone.  Bone tends to be “holey” to allow blood vessels to go through the living bone.  Shell on the other hand, is not porous and meant to be more “solid.”


It is every drop of water’s dream to live at sea level. Water precipitates on land and travels to sea through rivers. The rivers erode the land and chemically dissolves the components of rocks into ions. Over eons of time, most elements become dissolved in seawater. These ions help give the "flavor" to salt water.

Salt in the ocean comes from rocks on land. The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid (which forms from carbon dioxide and water).

Many of these ions can be combined into molecules that are used by living organisms. For example, little critters (protist) like foraminifers require CaCO3 (calcium carbonate) to make skeletons. Radiolaria, another protozoa require SiO2 (silica dioxide) to make their skeleton. Small plants, mainly diatoms which live on the ocean’s surface use SiO2 to make their skeleton.  Diatom contribute the majority of oxygen in the water and the atmosphere. 

Calcium carbonate usually crystallizes as calcite or aragonite seawater. The outcome affects many different processes — including the global carbon cycle, neutralizing carbon dioxide in the atmosphere into a stable mineral and limiting its buildup in the air. It also affects the formation of shells and corals, whose aragonite shells are vulnerable to the ocean acidification associated with climate change.

Bone is made of calcium phosphate. The mineral component is composed of hydroxyapatite, which is an insoluble salt of calcium and phosphorus. About 65% of adult bone mass is hydroxyapatite.   Bone also contains small amounts of magnesium, sodium, and bicarbonate.

Remember life evolved from marine to land.  Fossils support this evolution.

Slide 10. Why are shells in the ocean

The ocean’s chemical system is complicated and always changing. The minerals are dissolved in water and are in solution until either chemical or biological reactions in the oceans precipitate the different compounds.

Organisms that live in the marine environment tend to use two types of compounds, calcium carbonate (CaCO3) and silica dioxide (SiO2). Biological processes can actually transform the ions into microscopic minerals that grow with the organism. Calcium carbonate is a mineral called calcite. When incorporated into a biological system it is usually in a "disordered" form called aragonite. Most mollusks use calcium carbonate in their shells.

Slide 11.  Radiolarians and Diatoms SiO2

Silica dioxide is also a common mineral, in the form of quartz. Siliceous sponges use opaline silica for its skeleton.

Siliceous organisms in the ocean, such as diatoms and radiolaria, are the primary sink of dissolved silicic acid into opal silica. Once in the ocean, dissolved Si molecules are biologically recycled roughly 25 times before export and permanent deposition in marine sediments on the seafloor. This rapid recycling is dependent on the dissolution of silica in organic matter in the water column, followed by biological uptake in the photic zone.

Silicate, or silicic acid, is a very important nutrient in the ocean. Unlike the other major nutrients such as phosphate, nitrate, or ammonium, which are needed by almost all marine plankton, silicate is an essential chemical requirement only for certain biota such as diatoms, radiolaria, silicoflagellates, and siliceous sponges. The dissolved silicate in the ocean is converted by these various plants and animals into particulate silica (SiO2), which serves primarily as structural material (i.e., the biota’s hard parts).

Slide 12. 

The life of the San Francisco Bay is dominated by little critters.  None of the organisms of the  San Francisco Bay mud life are exceptionally beautiful nor unique, but all are part of a  food web.

In an ecosystem, organisms play different roles in the food web.  There are primary producers, primary consumers, and then different levels of secondary consumers.  

However before you determine the position of an organisms in a food web you need to identify the organisms first.   In this lab, the students will first take a look at the different organisms  of the mud  (from the San Francisco Bay) and then they will analyze their positions in the food chain.

Slide 13.  San Francisco Bay Mollusk Fauna

Gastropods are a diverse group of mollusk.  Some are herbivores and some are carnivores.  The carnivore gastropods have an enhanced "radula" that can drill through a shell from either a clam or gastropod.  So in recent shells you can determine how the shells died.

Read Murder in the Mud (storybook), which tells a story of the food chain in the San Francisco Bay mud.

Slide 14.   Interpreting Data
This is a good eample of how we can see how a clam died by looking for evidence of predation.  Using the information on the bay mud fauna by looking for these “holes” or borings.  It gives you some idea of how organisms die in the past.  Present is Key to the Past.

Slide 15.  Capitola, California

Capitola is a small community on the north part of the Monterey Bay.  It is noted for its nice sunny days and surfer waves, especially for beginners. Its cliffs are impressive, revealing a look through time.  Notice how steep the cliffs are near the beach.  These rocks tell a story of life during the Miocene to Pliocene.

Slide 16.  Purisima Formation in Capitola

The Purisima Formation is an environment of shallow marine (marine terraces) that were deposited from the Miocene to Pliocene (3-7 million years ago).  Many of these layers of fossils were caused by storms in shallow seas that ripped up clam beds and redeposited them on what we call marine terraces.  Uplift in the area caused by emerging coastline due to faulting.  You can trace this type of fossil and sediment formation along the coastline.   You also find other marine mammal and invertebrate fossils.

Slide 17. 
Changes due to Plate Tectonics.

Oceans is home to many organisms, and their skeletons tell a story of change through time.   So when you find shells in the mountains, you need to consider that the mountains were under ocean.  Tectonic forces change ocean to land (and land to oceans).   

Need to consider that as land masses move, the wind and currents change also.  Erosion of land will input dissolved elements in the water.  Organisms will adapt…. Present is key to the past.  Together the information provides a story of a changing world. 

Climate change occurs naturally, fueled by the changing land and water masses.  Chemical reactions on land and water also play a major role.  Humans because of their ability to change their surrounding do contribute to the overall chemical cycling, and can cause major changes over a shorter period of time. 

Slide 18.  The key part for children to understand is that change is part of the evolution of the Earth and life.  Science helps us understand how it changes.