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Classification and Marine Biodiversity Essay

Important Background Information that you need to know and understand: (Understand the Key Concepts) Key words: binominal system of naming; science of classification is taxonomy; species; levels of classification (know them); dichotomous identification key; 5 kingdoms; etc…

Our oceans have a great variety of life forms. Thousands of new species are discovered each year. We need to identify, name, and know the biology of all the marine species. To understand this huge array of species, a simple classification system is used to produce some order out of chaos. Example: this class has persons of all sorts of shapes, sizes, colour, eye colour, finger shape & size, etc….what criteria would you use to separate us all out?

Historically, we group things according to their likeness or use. There were grouping such as edible, poisonous, or medicinal. In your own dialect, you have local names for the edible things on the reef but there is no name for sponges, ascidians, and nudibranchs which you have no use for. There are only general names for corals, sharks, etc. In Fiji, we have no names for the deepsea snappers because we never caught and eat them but in Hawaii and Kiribati, you have different names for different deepsea snappers because you have caught them for generations. Fiji have large lagoonal areas and never needed to fish off-shore..

25 years ago, Fijian students knew the local names of fish. Today, many students have lost that knowledge because they rarely go back to the village.

Aristotle is the first scientist to classify all living things. John Ray developed keys to identify animals. Linnaeus (1707-1778), a Swede invented a simple naming system which we still use today (binominal nomenclature) made up of 2 Latinized words (genus species). e.g. Homo sapiens (in italics or underlined with the first letter in the genus is in capital). The genus or species may be descriptive or named after a person or place. Using scientific names shows scientific exactness as compared to common names which can be very general. Example: Siganus uspi Woodland and Gawel, 1974. Genus, species, describers, year they described it in.

Members of a group share many characters. We use characters which do not change e.g. structure and method of reproduction. Characters can be countable (number of fins) or expressed as a % of total length (head length etc); Characters can be absent or present. Colour can be used as a secondary character as it can change with the environment (and fade after preservation). Fossil records are used to find out about the evolution of groups of organisms. DNA is now used to separate species too.

The science of classification is taxonomy. A person who classifies things is a taxonomist.

5 kingdoms: animalia; plantae; fungi; protista; monera. Protista have distinct nucleus, monera has indistinct nucleus. See kingdom of living things on page 207. You may wish to break your classification into vertebrates and invertebrates.

The categories are (classifying you)
Kingdom: Animalia
Phylum: Chordata
Sub Phylum: Vertebrata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens

What is a species: A species is a group of organisms (basically alike) and can interbreed under natural conditions to produce fertile off spring.

Consider a mule (horse x donkey); a liger (lion x tiger). Infertile off springs. Butterfly fishes can hybridize.

Marine Biodiversity

Biodiversity refers to the number and variety of earth’s life forms (remember the 5 kingdoms).

KNOW THE Importance of biodiversity
1. If you care about the environment, you must feel strongly that other living things have a right to survive alongside each other. Other organisms do not need to benefit humans directly to have a right to exist.

2. By protecting the earth’s biodiversity, we are ensuring my own survival. As we learn about the amazing complexity of earth’s biodiversity, we will discover more and more direct benefits.

3 types of diversities
1. genetic biodiversity (refer to genetic variety and variability within each species – genes vary between individuals within a species). Use your class as an example and see the differences – not only in colour but body shape and sizes, eye color, hair colour, skin color, shapes of hands etc. Marine species also show variability in shape and colour. 2. species biodiversity (refer to the number of different species living on earth) 1.8 million species has been discovered and described by scientists. We think there may be between 5 and 100 million species. Disappearing species- serious loss of biodiversity due to overfishing for food/use as well as increased nutrient levels caused by from pollution from the land. Old timers tell you about the amount of marine life off Suva 30 years ago-if we don’t start conserving biodiversity, we may only see them in marine parks or preserved as a specimen in museums. Endemic species-only found in a certain country e.g. Siganus uspi (USP rabbitfish) only found in Fiji. 3. ecosystem biodiversity- refer to variety in the combination of species that form ecosystems such as ponds, coral reefs, forests, or grassland. It is the variety of ecosystem types that is ecosystem diversity.

An ecosystem can be as large as the Great Barrier Reef or as small as the back of a spider crab (that allows sponges, algae and worms to grow on the shell).

Biodiversity in the ecosystems is not just the number of different species; it is the variation within them and the different roles they have in forming the ecosystems.

Ecosystems are complex because they are formed by a variety of interactions between species. One interaction is food web; provide an attachment base for others; alter current and light patterns; provide camouflage, shelter or compete for space.

Ecosystems are functional units of the marine world. Small worms are just as important as large whales because each have a vital role to play in the ecosystem. Humans interfere and the naturally-balanced ecosystem becomes unbalanced (if we take all the herbivorous fish, the algae would grow vigorously and push out the corals on the coral reef).

Ecosystems are dynamic…changed by physical and biological processes (tides, storms, succession, & humans).

An ecosystem applies interactions over large and over small scale. Fish from the lagoon ecosystem depend on the mangrove ecosystem (as juvenile nursery ground) and on coral reef ecosystem (as a feeding ground).

Ecosystems can be classified at different scales using parameters such as geology, coastal landforms, water temperature’ salinity, currents, upwellings, wave exposure, depth, and patterns of major life forms (e.g. seagrass).

Proper functioning of the marine environment is dependent on its ecological integrity (all components are present, operational and ecological viable).

Marine ecosystems are continually changing to meet the changing conditions.


Biogeography is the name given to the study of the distribution of life on earth. We may look at the windward side and leeward side of the Fiji group. The marine environment on the windward side is affected by the tradewinds which bring strong currents which in turn wash away the sediments. It is more rainy too. The leeward side has less wind and less wave action so sediments stay around. Nutrients from the land do not get disperse quickly.

We can also look at the northern areas of Fiji and Rotuma (hotter) and the southern areas including Kadavu and Minerva Reef (cooler). Because the conditions are different, the organisms living there may differ too.

Biodiversity and Marine Life
The text book does not cover this topic.
Plankton (all animals and plants that live in the water but drift about at the mercy of wind and currents). (Nekton can swim against the current e.g. fish). Those organisms that spend all their lives in the plankton are called holoplankton. Those that spend only part of their lives in the plankton are called meroplankton. Plankton are usually small but they can be up to 1.5m across e.g. large jellyfish.

Phytoplankton are plant plankton and zooplankton are animal plankton. Plankton is collected by plankton nets (either by a horizontal tow or a vertical tow).

Plankton are important because many are the larval stages of marine animals we see. Plankton provides food for many of the filter feeders in the marine environment (from whales to invertebrates to other plankton). Phytoplankton also produces oxygen to release into the atmosphere. Plankton support major fisheries. They recycle nutrients in the microbial loop.

Examples of Phytoplankton: diatoms and dinoflagellates (causes fish poisoning). Examples of Zooplankton: copepods, jellyfish. Sunfish, arrow worms.

To keep afloat (stay in the epipelagic zone) plankton swim weakly, have body fluids which are less dense than seawater, actively exude heavy ions, have gas filled sacs, use oils and fats (diatoms and fish eggs have oil), have parachute like forms (slow their sinking rate) or growing spiny appendages (also makes them harder to eat), or have watery tissue (jelly-like).

Moffatt, B; Ryan, T; and Zann, L 2003. Marine Science for Australian Students. pp608. Wet Papers Publications.

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