FHS 101 Notes

Lecture 1 - Life in the Marine Environment


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Chapter 1 Castro and Huber

Marine Biology the study of organisms that live in the ocean (plants, animals, protists, ect.)

-         70% of the earth is covered by oceans

-         oceans provides food, medicine, recreation, and habitats for many organisms

 -         marine organisms provide much of the oxygen we breath and help regulate weather patterns on earth

 -         oceans also provide dangerous organisms that can cause disease or injure humans

 -         marine biology includes many disciplines of biology from chemistry to organismal biology

 -         Aristotle is considered to be the first marine biologist he described many forms of marine life he was the first to recognize that gills are the breathing apparatus of fish

 -         Many voyages took naturalists Darwin (sailed on HMS Beagle) made significant contributions to marine biology described plankton and barnacles

 -         The Challenger expedition laid the foundations for modern marine biology 3 years sailed around the world collecting data on the sea floor and organisms collected samples of thousands of previously unknown species

 -         Today, we have permanent marine laboratories on coasts can study live organisms ROVs (remote operated vehicles, underwater robots) and SCUBA (self contained underwater breathing apparatus), and satellites record data about ocean currents


Chapter 3 (pg. 47-48) and Chapter 4 (pg. 74-81, 84-89)

 Life in the Marine Environment:  all living organisms are made of cells they are organized, grow, metabolize, react to the environment, and reproduce

 All of the major divisions of the animal kingdom have members in the marine environment because all originated there.  There is greater biodiversity (the number of species in an area) in the ocean than on land.

 5 phlya are exclusively marine.

 The ocean is a more stable environment than terrestrial environments, so organisms are highly sensitive to changes in temperature, turbidity, and salinity.

 The marine environment involves abiotic (non-living) and biotic (living) factors.  We will examine both abiotic and biotic factors.

 -         Abiotic factors include temperature and salinity.

-         Biotic factors include predation and relationships among organisms.


 Divisions of the marine environment: organisms adapt to the habitat they live in

 1.      Pelagic environment open ocean, plankton drift in the water, nekton swim

 2.      Benthic environment ocean bottom

 Habitat - where an organism lives

 Levels of Organization of Biological Systems

 Cells Tissues organs Organ Systems Organism Population Community Ecosystem

 Population groups of organisms of the same species that occur together a group of             mussels living together

Community all of the population in a particular habitat the mussels, crabs, and fish   living in a seagrass bed, how the organisms interact

Ecosystem a community or communities in a large area together with the physical        environment the seagrass bed community along with the physical factors including  tides, waves, nutrients, temperature, ect.                                               


Challenges of Life in the Sea


1.      Salinity the total amount of dissolved solids in the ocean water, stated as parts per thousand (ppt or 0/00), average salinity approximately 35 ppt (35 grams of salt in 1000 grams of water), ocean ranges from 0-44 ppt


            Major components of the ocean (ions, atoms with positive and negative charge): Cl

and Na account for 85% of all salts, these 6 account  for 95% of all salts:

Chloride (Cl) most abundant

Sodium (Na)

Sulfate (SO4)

Magnesium (Mg)

Calcium (Ca)

Potassium (K)


As salinity increases, density increases.  (More salts in the water mean more dense water).  Density is a measure of mass of a given volume of a substance.  More salt means the water will weigh more.

 Halocline a zone in the water column where the salinity increases drastically

 But how do organisms deal with changes in salt water concentrations?

 Diffusion the movement of ions and molecules from areas of high concentration to areas of low concentration.  (Ex. Dissolving sugar in water, ink drop spreads out in water)

 Osmosis the diffusion of water from high concentration to low concentration


Two types of organisms in marine environments when it comes to dealing with  salinity:

 Osmoconformers internal concentration changes passively with the external concentration of water surrounding them, so they have to stay where the salinity of the water matches the salinity of the inside of the cells, such as the open ocean where salinity doesnt change much, also called stenohaline can survive in a narrow salinity range, Ex. Molluscs and polychaetes (with soft bodies)

Osmoregulators organisms actively control their internal concentration to match the external concentration by regulating internal environment physiologically, can selectively absorb/release ions, also called euryhaline can survive in a wide range of salinities (Ex. Crabs, fish)

Ex. marine fish drink seawater and excrete excess salt through gills and urine


2.      Temperature the ocean ranges from -2 to 30 C (28-86 F)

             - most marine animals (invertebrates and fish) are ectotherms (poikilotherms) or cold-blooded body temp changes with the surrounding environment, many marine animals become sluggish in cold water and metabolism increases in warm water


Stenothermal can survive in a narrow temperature range

Eurythermal can survive in a wide temperature range

Thermocline a zone in the water column where the temperature drops drastically, cold water is more dense than warm water

             -mammals, birds, and some fish are endotherms (homeotherms) or warm blooded able to keep body temperature constant even when the external temperature changes, some fish (tunas, sharks) retain heat in their muscles allowing them to remain active in cold water and move over large distances control their own metabolism, uses a lot of energy

             Adaptation an inherited characteristic that enhances an organisms ability to survive     and reproduce in a particular environment.

             The adaptation to different environments has led to many different species.

 Species a population of organisms with common characteristics that can successfully breed with each other to produce fertile offspring.

 Taxonomy the organizing, naming, and classifying of organisms, there is an 8 category classification system used today consisting of:


Domain                        general






Genus a group of similar species

Species                        specific


There have been 1.75 million living species identified, and scientists estimate that millions more remain to be discovered.


Every species has a different Genus species name.  This two-name system of naming organisms is called binomial nomenclature (developed by Carolus Linnnaeus).  Always underline or italicize genus and species names.  Common names vary from place to place, scientific names are the same all over the world.


Ex. Canis familiaris = dog (genus Canis) includes wolves Canis lupus and coyotes Canis latrans


Ex. Homo sapien = human


Domains Bacteria, Archae, Eukaryota


In Domain Eukarya, there are 4 kingdoms Protista, Fungi, Plantae, and Animalia



Chapter 5 Marine Microorganisms live everywhere in the ocean form the basis of the food chain in the ocean

                         1. Bacteria (Domain Bacteria)

        simplest forms of life, smallest cells

        some photosynthesize (autotrophs) primary production

        some heterotrophs grow well in sediment or decomposing organic matter important in the marine environment because they decompose organic matter recycling essential nutrients into the environment this feeds many benthic animals, they also degrade oil from oil spills, important to the marine food web



                            2. Cyanobacteria (Domain Bacteria)

-         Blue green algae

-         First Photosynthetic bacteria on earth

-         Important to the accumulation of oxygen in the atmosphere

-         Can tolerate wide range of salinity and temperature

-         Cause Red Tides an bloom of cyanobacteria with a red pigment


       3. Unicellular Algae (Domain Eukarya, Kingdom Protista)


            4 types of unicellular algae:


1. Diatoms unicellular, can form chains or groups

-         cell walls made of silica (glass like)

-         contain two halves that fit together like a box

-         important primary producers in cold waters

-         part of the plankton

-         have a yellow brown color because of their pigment

-         can cause algae blooms


 2. Dinoflagellates unicellular

-         part of the plankton

-         have two flagella

-         have armored plates made of cellulose

-         important primary producers in warm waters

-         can cause algae blooms red tides

-         can produce light and cause bioluminescence you can see when moving through the water at night

-         a specific type of dinoflagellate called zooxanthellae live in symbiosis with corals (corals use organic material (carbon) made by the dinoflagellate by photosynthesis for food and zooxanthellae get nutrients and a place to live from the coral) mutualism


                        3.  Foraminiferans have a shell of calcium carbonate, eat diatoms


                        4.  Radiolarians shells made of silica (glass like)

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Last modified: 07/14/10