Marine Biology

Introduction: Science and Marine Biology 2. Fundamentals of Ecology 3. Marine Provinces 4. Seawater 5. Tides 6. Biological Concepts 7. Marine Microorganisms 8. Multicellular Primary Producers 9. Sponges, Cnidarians, and Comb Jellies 10. Worms, Bryozoans, and Mollusks 11. Arthropods, Echinoderms, and Invertebrate Chordates 12. Marine Fish 13. Marine Reptiles and Birds 14. Marine Mammals 15. Intertidal Ecology 16. Estuaries 17. Coral Reef Communities 18. Continental Shelves and Neritic Zone 19. The Open Ocean 20. Life in the Ocean’s Depths 21. Marine Birds and Mammals in Polar Seas 22. Artificial Reefs 23. Marine Protected Areas 24. Impact of Tourism on the Marine Environment 25. The Global Trade of Marine Ornamental Species

BIOL 181: Life in the Oceans – Lecture Notes

2

1. Introduction: Science and Marine Biology (The majority of the text below originally appeared as chapter 1 of Introduction to Marine Biology)

1.1. Science and Marine Biology

Oceans cover 71 percent of the earth, and affect climate and weather patterns that in turn impact

the terrestrial environments. They are very important for transportation and as a source of food,

yet are largely unexplored; it is commonly said that we know more about the surface of the moon

than we do about the deepest parts of the oceans!

Oceanography is the study of the oceans and their phenomena, and involves sciences such as

biology, chemistry, physics, geology, and meteorology. Marine biology is the study of the

organisms that inhabit the seas and their interactions with each other and their environment.

1.2. Brief History of Marine Biology

Marine biology is a younger science than terrestrial biology, as early scientists were limited in

their study of aquatic organisms by lack of technology to observe and sample them. The Greek

philosopher Aristotle was one of the firsts to design a classification scheme for living organisms,

which he called ―the ladder of life‖ and in which he described 500 species, several of which were

marine. He also studied fish gills and cuttlefish. The Roman naturalist Pliny the Elder published

a 37-volume work called Natural History, which contained several marine species.

Little work on natural history was conducted during the middle ages, and it wasn’t until the late

eighteenth century and early nineteenth century that interest in the marine environment was

renewed, fueled by explorations now made possible by better ships and improved navigation

techniques. In 1831, Darwin set sail for a five-year circumnavigation on the HMS Beagle, and

his observations of organisms during this voyage later led to his elaboration of the theory of

evolution by natural selection. Darwin also developed theories on the formation of atolls, which

turned out to be correct. In the early nineteenth century, the English naturalist Edward Forbes

suggested that no life could survive in the cold, dark ocean depths. There was little basis for this

statement, and he was proven wrong when telegraph cables were retrieved from depths

exceeding 1.7 km deep, with unknown life-forms growing on them. In 1877, Alexander Agassiz

collected and catalogued marine animals as deep as 4,240 m. He studied their coloration patterns

and theorized the absorption of different wavelengths at depth. He also noted similarities

between deepwater organisms on the east and west coast of Central America and suggested that

the Pacific and Caribbean were once connected.

Modern marine science is generally considered to have started with the HMS Challenger

expedition, led by the British Admiralty between 1872 and 1876. During a circumnavigation that

lasted 3.5 years, the Challenger sailed on the world’s oceans, taking samples in various

locations. The information collected was enough to fill 50 volumes that took 20 years to write.

The samples taken during the Challenger expedition led to the identification of over 4,700 new

species, many from great depths, and the chief scientist, Charles Wyville Thomson, collected

plankton samples for the first time.

BIOL 181: Life in the Oceans – Lecture Notes