4 3.1 OCEAN LIFE 3.1 OCEAN LIFE 3.1.1 Origin Of Life The story of the origin of life on Earth goes almost as far back as when the Earth itself was young about 4,500 million years ago (MYA).Geologists have segregated Earth’s long historical timeline into a set of divisions called Eons, Eras, Periods and Epochs. The divisions are drawn based on certain key events that occurred towards the end of each division and caused a dramatic shift in the number and type of species in the oceans and on Earth.This information is largely drawn from studying fossils, and continues to be modified and corrected as geologists and other scientists obtain and analyze more data. Each geologic time period can be characterized by specific land forms and climates, animals and plants.The rest of this section describes our understanding of some key events that occurred in the Precambrian when life first formed in the ocean.
6 3.1 OCEAN LIFE PRECAMBRIAN – 4,500 MYA TO 543 MYA The early Earth about 4,500 million years ago was very different from today because it had no ocean or air and was constantly bombarded by planetoids and other materials left over from the formation of the solar system. This bombardment, combined with heat from radioactive breakdown and heat from the pressure of the planet’s contraction, caused the Earth to be fully molten during early Hadean time.The Earth CoolsOver time, the Earth cooled. Molten material began solidifying into rock and continental plates began to develop during the Archaean Era about 3,800 million years ago.Early AtmosphereThe atmosphere during the Archaean was composed of methane, ammonia and other gases which would be toxic to most life on Earth today. The atmosphere also contained a great deal of water vapor which became liquid as it cooled.
7 3.1 OCEAN LIFEEarly LifeBy examining some of the oldest sedimentary rocks on Earth, scientists have concluded that life on Earth started in the ocean. Life first appeared on Earth early in the Archaean. The oldest fossils date to roughly 3,500 MYA and consist of bluegreen bacteria. In fact, all life on Earth for the next 1,000 million years was probably bacterial. By about 2,500 MYA, during the Proterozoic Era, abundant fossils of living organisms, mostly blue-green bacteria, can be found. Then, about 1,800 MYA, simple eukaryotic cells (cells with a nucleus) started appearing.Late AtmosphereThe middle Proterozoic saw an oxygen buildup in the atmosphere which was probably caused by photosynthetic organisms in the oceans. Photosynthesis is the process by which organisms (e.g. blue-green bacteria, green algae, and plants) use carbon dioxide, water and sunlight to produce carbohydrates and oxygen as a by-product. Carbon dioxide, nitrogen and ozone levels also built up. The atmosphere’s ozone layer formed which screened developing life from the effects of the Sun’s ultraviolet radiation. This atmosphere made possible the explosion of new life forms toward the end of the Proterozoic, including multi-cellular algae and animals.
8 3.1 OCEAN LIFE First Multi-Cellular Animals One of the oldest known groups of multi-cellular animals is the cnidarians, which include the sea anemones, corals, hydroids, siphonophores, true jellyfish and box jellyfish. Fossil records date back to the Precambrian (about 550 MYA).REFERENCES & FURTHER READINGOcean Literacy Principle 4(a)Most of the oxygen in the atmosphere originally came from the activities of photosynthetic organisms in the ocean.Ocean Literacy Principle 4(b)The first life is thought to have started in the ocean. The earliest evidence of life is found in the ocean.
9 3.1 OCEAN LIFE 3.1.2 Extreme Ocean Life Ocean life is full of extremes with some of the most ancient, smallest, largest, and most poisonous creatures found there.MOST ANCIENTSome of the oldest organisms include the blue-green bacteria which are about 3,600 million years old. Some of the oldest multi-cellular animals are the cnidarians which are about 550 million years old. In contrast, recognizable humans are only about 2 million years old.SMALLEST ANIMALSSome of the smallest organisms found in the oceans include viruses, bacteria and other microbes.LARGEST ANIMALSThe largest creature that has ever lived on Earth is the blue whale. Adult females are the largest and measure 33m (108 ft) in length. Their tongue alone weighs the same as an elephant. The lion’s mane jellyfish can also be very long reaching 30m (100 ft) in length.OLDEST ANIMALRecent research has pointed to a species of clam as being the oldest creature alive. A clam dredged up off the coast of Iceland is thought to be the longest-lived mollusc discovered. Scientists estimated that the ocean quahog was aged between 405 and 410 years old. The clam was nicknamed “Ming” after the Chinese dynasty that was in power when it was born.
10 3.1 OCEAN LIFE LARGEST PREDATOR The largest predator is the sperm whale (Physeter macrocephalus). It is also the largest of the toothed whale species. Males are usually about twice as large as the females. Adult males can grow up to 18 m (60 ft) long and weigh 36,300 kg (80,000 lbs). They have a long life span living up to 70 years. Sperm whales have been found living in every ocean in the world. Sperm whales have strong conical (cone shaped) teeth in their lower jaw and only remnants of teeth inthe upper jaw. The largest teeth are 28 cm (11 in) long and used when hunting prey such as giant squid. Herman Melville’s sea-faring adventure, written in 1851, features the “white sperm whale” known as “Moby Dick”.LARGEST PREDATORY FISHThe largest predatory fish known is probably the Megalodon shark. At a length of more than 15 m (50 ft), Megalodon was larger and heavier than Tyrannosaurus rex and had teeth 18 cm (7 in) long. Megalodon is the largest predatory fish that has ever lived and is second only to the sperm whale as the largest predator our planet has ever produced. In comparison, the great white shark is “only” 7 m (23 ft) in length.
11 3.1 OCEAN LIFE MOST POISONOUS The most poisonous animals are probably either sea snakes or box jellyfish, which are both found in Australia. Being bitten by a sea snake or stung by a box jelly, such as the finger-nail sized Carukia barnesi, can be fatal to humans with death occurring in minutes. Box jellyfish are also found in the Caribbean Sea and while their stings are less dangerous than their Australian relatives, they are still very potent.DEADLIESTIn the ocean, candidates for the deadliest creatures include killer whales, some sharks (e.g. bull shark, great white shark or tiger shark), sea snakes or box jellyfish. On land, spiders (e.g. funnel web spiders) or snakes (e.g. cobras) are the most deadly. More subtly, humans, mosquitoes, tsetse flies or other disease-carrying insects can also be considered deadly.Ocean Literacy Principle 5(a)Ocean life ranges in size from the smallest virus to the largest animal that has lived on Earth, the blue whale.REFERENCES & FURTHER READING- Sperm whale- Megalodon shark- Ming the clam is oldest mollusc (Oct/28/2007)
12 3.1 OCEAN LIFE 3.1.3 Classification All living organisms can conveniently be grouped together in a number of ways. One traditional way to group organisms is to compare internal and external features of an organism and group them according to these features.GROUPSAt the top level, all organisms are placed into one of five groups called “kingdoms” as follows:1. Monera – prokaryotes (includes Eubacteria and Archaebacteria)2. Protista – protists3. Fungi – fungi and related organisms4. Plantae – plants5. Animalia – animalsKingdoms are further divided into groups called phyla (plural; phylum – singular). Each phylum is divided into classes, each class into orders, each order into families, each family into genera, and each genus into species as follows:• Kingdom• Phylum• Class• Order• Family• Genus• Species
13 3.1 OCEAN LIFESome examples of these major groups are illustrated below:KingdomAnimaliaPlantaeProtistaPhylumChordataTracheophytaAmoebozoaClassMammaliaAngiosperm-OrderCetaceaNajadalesEuamoebidaFamilyPhyseteridaeHydrocharitaceaeAmoebidaeGenusPhyseterThalassiaAmoebaSpeciesmacrocephalustestudinumproteusAt the bottom level, the genus and species name uniquely identify the organism. A species represents one type of organism, such as Physeter macrocephalus (sperm whale), Thalassia testudinum (turtle grass) or Amoeba proteus (the common amoeba).
14 3.1 OCEAN LIFEConventionally, the genus (e.g. Physeter) is written in upper case and the species (e.g. macrocephalus) is in lower case. The genus and species is also underlined or italicized. Well-known examples include Homo sapiens (humans), Orcinus orca (killer whales) and Carcharodon carcharias (great white sharks).Several variations of the genus and species name are also sometimes used for convenience. If you are not sure what species an organism is precisely or if it is not particularly relevant, the abbreviation “sp.” can be used. Thus, if you are referring to some species of the sea grass Thalassia, it might be written Thalassia sp. Alternatively, if you are referring to several species of the sea grass Thalassia, you might write Thalassia spp. Finally, if you are referring to the same species repeatedly, it is convenient to abbreviate the genus name to just an initial with a full stop punctuation mark. For example, Tyrannosaurus rex is often abbreviated to T. rex.
15 3.1 OCEAN LIFE KEY TO THE 5 KINGDOMS Biologists develop “keys” to help them determine what an organism is and how to classify it. Suppose you see something in the ocean that appears to be living. How do you classify it? The following is a key that you might use to determine which of the 5 kingdoms to which it belongs:1. Is it green or does it have green parts?• Yes – go to 2• No – go to 32. It may be a plant, protist or moneran (blue-green bacteria). Make sure that the green is really part of the organism and not something green an animal might have eaten.• Is it single-celled? Yes – go to 6• Is it multi-cellular? Yes – it is a plant (Plantae). Look for cell walls and other internal structures. Under a microscope you might be able to see chloroplasts.3. It could be a moneran, protist, fungus, or animal.• Is it single-celled? – Yes, go to 4• Is it multi-cellular (look for complex or branching structure, appendages)? – Yes, go to 5
16 3.1 OCEAN LIFE4. It could be a moneran or a protist. Can you see any details inside the cell?• Yes – it is a protist (Protista). You should be able to see at least a nucleus and/or contractile vacuole, and a definite shape. Movement should be present, using cilia, flagella, or amoeboid motion. Cilia or flagella may be difficult to see.• No – it is a moneran (Monera). It should be quite small and may be shaped like short dashes (rods), small dots (cocci), curved, or spiral shaped.5. It could be an animal or a fungus. Is it moving?• Yes – it is an animal (Animalia). Movement can be by cilia, flagella, or complex, involving parts that contract. Structure should be complex. Feeding activity may be obvious.• No – it is a fungus (Fungi). Should be branched, colorless filaments. May have some kind of fruiting body (mushrooms are a fungus, don't forget). Usually attached to some piece of decaying matter - may form a fuzzy coating on or around an object.6. It is probably a protist (Protista) but could be a moneran. Most green protists are flagellates, that is, they move rapidly with a spiraling motion. It might also be a colonial protist, such as Volvox, which forms a spinning ball of green cells. However, if it consists of long, unbranched, greenish filaments with no apparent internal structure, it is probably a blue-green bacterium (sometimes mistakenly called blue-green alga), a moneran.
17 3.1 OCEAN LIFEGenerally, the more closely you observe the organism, the more certain you can be. However, many living things have stages that make them resemble members of another kingdom. Thus, depending on when you observe the features and what the precise features are, you may place an organism incorrectly into a group – classification can be a complicated process.REFERENCES & FURTHER READING
18 3.1 OCEAN LIFE 3.1.4 Major Oceanic Organism Groups Most life in the ocean exists as micro-organisms or microbes including bacteria, blue-green bacteria and plankton. Microorganisms such as blue-green bacteria and phytoplankton (plant plankton) are the most important primary producers in the ocean. Not only are they the most abundant life form in the ocean, they also have extremely fast growth rates and life cycles.We do not know how many species there are in the ocean or, indeed, on Earth. Estimates range from a few million to as many as 30 million of which we only know a small fraction!DIVERSITYBiodiversity is a measure of the number of species in an ecosystem. For example, there are many different species of fishes but only a few species of sea otters. Fishes are, therefore, considered much more diverse than sea otters.The diversity of major groups of organisms is much greater in the ocean than on land with some major groups found exclusively in the ocean.One of the most diverse groups of animals in the ocean is the crustaceans. The crustaceans consist of some 39,000 known species distributed worldwide. Crabs, lobsters, and shrimps are among the best-known crustaceans but the group also includes an enormous variety of other forms.Ocean Literacy Principle 5(b)Most life in the ocean exists as microbes. Microbes are the most important primary producers in the ocean. Not only are they the most abundant life form in the ocean, they have extremely fast growth rates and life cycles.Ocean Literacy Principle 5(c)Some major groups are found exclusively in the ocean. The diversity of major groups of organisms is much greater in the ocean than on land.Interesting!The naturalist, J. B. S. Haldane, was asked by a cleric about what he might infer about the Creator, based on his wide ranging study of life. Haldane supposedly replied “the Creator, if He existed, must have had an inordinate fondness for beetles" based on the then current count of beetle species at around 400,000.
19 3.1 OCEAN LIFE MAJOR OCEANIC ORGANISM GROUPS The following outlines some of the major groups of organisms found in the ocean from within the 5 kingdoms:1. Monera – Prokaryotes (Eubacteria & Archaebacteria)Prokaryotes are unicellular organisms that lack a true nucleus with genetic material composed of a single molecule of double-strandedDNA. Nearly all prokaryotes have a rigid cell wall and may or may not be able to move. They include bacteria and the blue-green bacteria (cyanobacteria).· Microbes / bacteria· Blue-green bacteria (e.g. Spirulina)Prokaryotes are usually microscopic in size although the blue-green bacteria are larger and resemble algae. Thus, they are green, filamentous, and quite long but they also have no visible structure inside the cell. They absorb nutrients through the cell wall or produce their own through photosynthesis. Blue-green bacteria are also sometimes called blue-green algae.
20 3.1 OCEAN LIFE 2. Protista (Protists) Protists are a diverse group of organisms including a variety of unicellular, colonial and multi-cellular organisms. Protists may move by cilia, flagella or by amoeboid mechanisms. They usually do not have a cell wall although some forms may have one. They have organelles (well-defined structures that have a particular set of functions within a cell) including a nucleus and may have chloroplasts so some are green and able to photosynthesize food. Nutrients are acquired by ingestion of other organisms, photosynthesis or both. Protists are further divided into three major groups:(a) Protozoa (Animal-like protists)Protozoans are mostly single-celled and motile animals thatfeed by phagocytosis. They are usually small (0.01–0.5 mm)and can conveniently be grouped by method of locomotion into:· Flagellates – with long flagella (e.g. Euglena)· Amoeboids – with transient pseudopodia (e.g. Amoeba)· Ciliates – with multiple, short cilia (e.g. Paramecium)· Sporozoa – non-mobile; form spores (e.g. Toxoplasma)Important!Phytoplankton (plant plankton) is a general term used to describe microscopic plants in the ocean. Phytoplankton is composed of many different species including:AlgaeDiatomsDinoflagellatesBlue-green bacteria
21 3.1 OCEAN LIFE (b) Algae (Plant-like protists) They include single-celled organisms, such as Euglena, that are also considered protozoa which have acquired chloroplasts. Some, such as seaweeds, are multi-cellular including members of the following groups:· Chlorophytes – green algae (e.g. Ulva (Sea Lettuce))· Rhodophytes – red algae (e.g. Porphyra)· Heterokontophytes – diatoms, brown algae (e.g. Macrocystis (Kelp))The green and red algae, along with a small group called the glaucophytes, appear to be close relatives of plants and some authors treat them as plants despite their simple organization.Most other algae, however, developed separately. They include the haptophytes, cryptomonads, chlorarachniophytes, dinoflagellates, and euglenids, all of which have also been considered protozoans.(c) Fungus-like protistsVarious organisms with a protist-level organization were originally treated as fungi, because they produce sporangia (spore producing structures (capsules) borne on the top of the sporophyte.) These include chytrids, slime molds, water molds and Labyrinthulomycetes. Of these, the chytrids are now known to be related to other fungi and are usually classified with them. The others are now placed among the heterokonts (which have cellulose rather than chitin walls) and the Amoebozoa (which do not have cell walls).Interesting!The dinoflagellates are difficult to classify because they have both animal and plant characteristics. They can be considered animals because they have 2 flagella which they use to move (an animal characteristic – plants can’t move!). However, they also have chloroplasts which they use to photosynthesize food (a plant characteristic – animals cannot photosynthesize food).
22 3.1 OCEAN LIFE 3. Fungi (fungi) Fungi are multi-cellular organisms. Each cell has a severalorganelles including a nucleus and a cell wall but they have nochloroplasts and no mechanisms for locomotion. Most fungigrow in terrestrial environments but several species occur onlyin aquatic habitats. Fungi range in size from microscopic tovery large (e.g. mushrooms). For the most part, fungi acquirenutrients from decaying material by absorption.4. Plantae (plants)Plants are multi-cellular organisms. Each cell has a nucleus,chloroplasts, and cell walls. Most cannot move although thegametes of some move using cilia or flagella. They are all ableuse sunlight to produce food through photosynthesis.By the seashore, plants such as mangroves, sea grapes andpalms are of special interest. In the ocean, plants such as seagrasses are important. Sea grasses are flowering plants fromfour plant families that grow in the marine environment:· Posidoniaceae· Zosteraceae· Hydrocharitaceae· Cymodoceaceae
23 3.1 OCEAN LIFE 5. Animalia (animals) Animals are multi-cellular and move with the aid of cilia, flagellaor muscular organs based on contractile proteins. Animal cellshave organelles including a nucleus but have no chloroplastsor cell walls. Animals acquire nutrients by ingestion. Some ofthe major animal groups found in the ocean include:(a) Vertebrates (animals with backbones)Fish· Bony fish – e.g. angelfish, groupers, etc.· Cartilaginous fish – e.g. sharks and rays· Jawless fish – e.g. hagfishes, lampreysReptiles· Marine iguanas· Sea turtles· Sea snakes· Alligators & crocodilesBirds· Puffins· Gannets· Guillemots· Razorbills· Penguins· Gulls
24 3.1 OCEAN LIFE Mammals · Sea otters · Pinnipeds – true seals, eared seals and walruses· Polar bears· Cetaceans – whales and dolphins· Sirenians – manatees and dugongs(b) Invertebrates (animals without backbones)Cnidarians· Sea anemones & corals· Siphonophores· True jellyfish· Box jellyfishPorifera· SpongesCrustaceans· Shrimps· Crabs· Lobsters· Barnacles
27 3.2 RELATIONSHIPS 3.2 RELATIONSHIPS Ocean biology provides many examples of life cycles, adaptations and important relationships between organisms including symbiosis and predator-prey dynamics. This section discusses several important relationships between living organisms and introduces several basic concepts to the reader.3.2.1 AdaptationAn “adaptation” is a characteristic that generally increases an organism's ability to survive within a changing environment.The following are examples of a variety of adaptations in fish:1. Mouth, Teeth & JawsThe mouths, teeth and jaws are adapted to the type of diet that specific fishes eat.For example, foureye butterflyfish have long, pointed mouths for plucking out coral polyps as food. They feed mainly on hard and soft corals (gorgonians), polychaete worms, and tunicates.In contrast, morays eels are predators that feed on fishes, octopuses, crustaceans and molluscs. They have long, sharp teeth and powerful jaws that can crush bone.Parrotfish have a parrot-like “beak” from fused teeth and strong jaws to help them bite into rock-hard coral structures and scrape off the algae and corals.Ocean Literacy Principle 5(d)Ocean biology provides many unique examples of life cycles, adaptations and important relationships among organisms (symbiosis, predator-prey dynamics and energy transfer) that do not occur on land.
28 3.2 RELATIONSHIPS 2. Body Shape Fish body shapes can take many forms such as fusiform (torpedo-shaped) for fast open-ocean swimming fish (e.g. tuna) or flattened/depressed for bottom-dwelling fish (e.g. flounders).3. ColorColor can be used for many purposes including camouflage, for disruptive effect to conceal them against their background (e.g. triggerfishes), for advertising a service (e.g. cleaner fish) or even a warning (e.g. lionfish)4. AppendagesSpecial appendages such as barbels (which look like whiskers) help fish “feel” for food (e.g. sturgeons, catfish or goatfish).REFERENCES & FURTHER READING
29 3.2 RELATIONSHIPS 3.2.2 Food Pyramid All organisms can be thought of as producers or consumers depending on whether they produce or consume food.PRODUCERSPlants and other photosynthetic organisms are producers because they can produce or make food from sunlight and raw materials. In the ocean, producers include blue-green bacteria, algae, seaweed, kelp, phytoplankton (plant plankton) and plants.CONSUMERSIn contrast, animals are consumers because they consume one another or plants – they cannot produce anything from sunlight and raw materials. Humans are consumers because we eat animals and plants.
30 3.2 RELATIONSHIPS FOOD PYRAMID A food pyramid shows the feeding relationship between producers and their consumers. There must always be more producers than consumers because otherwise you would run out of food. Thus, there are more plants than primary consumers, more primary consumers than secondary consumers, and more secondary consumers than tertiary consumers. At the top of the food pyramid, there are very few animals because it takes so many animals and plants to support them. For example, there are very few great white sharks because it takes a large number of seals, sea lions, and fish to feed them.When an animal or a plant becomes extinct, the whole food pyramid is affected. For example, if a plant goes extinct, the primary consumer that feeds upon it may also go extinct if it cannot find an alternative food source. Similarly, if a primary consumer goes extinct, a secondary consumer that depends on it may go extinct which may affect a tertiary consumer in a chain reaction.An animal that hunts and eats other animals is called a predator while animals that are hunted are known as prey. An animal that only eats meat is known as a “carnivore” while an animal that only eats plants is known as a “herbivore”. An animal with a mixed diet is known as an “omnivore”. There must always be fewer predators than prey otherwise the predators would eventually consume everything and starve. As a result, there are progressively more animals going down a food pyramid. At the base of the food pyramid, plants far outnumber animals.
32 3.2 RELATIONSHIPS 3.2.3 Predator-Prey The act of predation is one in which one organism consumes all or part of another. As such, it can include a normal predator-prey relationship (e.g. a shark preying on another fish) as well as herbivore-plant or parasite-host interactions.These linkages are the prime movers of energy through food chains and are an important factor in the ecology of populations determining the mortality of prey and birth of new predators.PREDATOR-PREY CYCLESInteresting!An animal can be both predator and prey. A tuna that eats other fish is a predator. However, the tuna is also prey to sharks. Some sharks prey on other sharks so sharks can be both predator and prey. Predators that are not consumed by any other animal (such as Great White Sharks) are known as “top predators”.A coupled predator-prey system will ordinarily cycle. In other words, predator numbers initially increase when prey are abundant. When prey numbers are driven to down as a result of excessive predation, the number of predators decline. As the number of predators decline, the number of prey recovers, which again leads to an increase in the number of predators.In the lab, predators often extinguish their prey and then starve. In nature, however, at least three factors promote cycling. First, due to slight variations in an environment, some prey may hide in areas where they escape detection by predators. Once predators decline, their prey can then fuel a new round of population increase. Second, prey may also evolve behavior patterns, armor, and other defenses that reduce their vulnerability to predators. Third, an alternative prey may also provide a kind of refuge because once a prey population becomes rare, predators be forced to hunt a different prey species.
33 3.2 RELATIONSHIPS DIVERSITY & TROPHIC EFFECTS Predation can have far-reaching effects on biological communities. For example, a sea star is the top predator upon a community of invertebrates inhabiting rock pools in the Pacific Northwest. The rest of the community included molluscs, barnacles and other invertebrates for a total of 12 species. When an investigator removed all the sea stars from the community, an acorn barnacle and a mussel began to occupy virtually all the available space out-competing other species. Species diversity dropped from 12 species to, essentially, just 2. The sea star was a keystone predator, keeping the strongest competitors in check. Although it was a predator, it also helped maintain diversity in the community.When non-native species (“exotics”) invade an area, they often create a domino effect, causing many other species to increase or decrease. For example, the rainbow trout was purposely spread to virtually all parts of the world where it could survive and be harvested as a valuable food fish. In New Zealand, however, the trout has out-competed native fishes, which are now found only above waterfalls that act as barriers to trout dispersal. As the trout is a more effective predator than the native fish species, the invertebrates that are prey to the trout are reduced in abundance wherever the trout are found. In turn, algae, which are grazed by the invertebrates, also increase because of reduced grazing pressure. This domino effect is an example of a trophic cascade and its effects can be very difficult to counteract or correct.
34 3.2 RELATIONSHIPS MORE EFFECTIVE PREDATORS & MORE EVASIVE PREY Natural selection tends to favour more effective predators and more evasive prey. Easily captured prey are eliminated while prey with effective defences that are rapidly inherited start to dominate the population. Evolutionary "arms races" have been recorded in many predator-prey relationships including for example, certain snails, which become more heavily armoured over time while their predators, crabs, develop more massive claws with greater crushing power.REFERENCES & FURTHER READING
35 3.2 RELATIONSHIPS 3.2.4 Symbiosis The term “symbiosis” defines a close and often long-term association between different biological species. The symbiotic relationship may be further categorized as mutualistic or commensal. Mutualism describes any relationship between individuals of different species where both individuals derive a benefit. In contrast, commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped. Symbiotic relationships included those associations in which one organisms lives on another (ectosymbiosis, such as mistletoe), or where one partner lives inside another (endosymbiosis, such as certain bacteria in humans or zooxanthellae in corals). Symbiotic relationships may be obligate (necessary to the survival of at least one of the organisms involved) or facultative (where the relationship is beneficial but not essential to survival of the organisms). There are many examples of symbiotic relationships in the ocean including the following:1. Clownfish / Sea AnemoneOne example of mutual symbiosis is the relationship between clownfish that dwell among the tentacles of sea anemones. The territorial clownfish protects the anemone by threatening and chasing away anemone-eating fish. In turn, the stinging tentacles of the anemone protect the clownfish from its predators (clownfish are coated with mucus that protects it from the sea anemone’s stinging tentacles).
36 3.2 RELATIONSHIPS 2. Cleaner Fish & Shrimp / Larger Fish Several species of cleaner fish and cleaner shrimp are found on coral reefs. These animals can be seen advertising their presence to larger fish by hovering in midwater and offering their cleaning services. They keep other fish clean and healthy by removing bits of dead or infected skin as well as skin parasites and fungi. In return, they obtain food and immunity from being eaten by the larger fishes.3. Corals / ZooxanthellaeCoral polyps form a symbiotic relationship with algae called zooxanthellae. Zooxanthellae are endosymbionts because they are symbionts (organisms that are part of a symbiotic relationship) that live inside (endo) the body of the coral. Zooxanthellae have both animal & plant features but are usually considered to be algae since they are able to utilize energy from sunlight and use it to convert carbon dioxide and water into oxygen and sugars (photosynthesis). When many zooxanthellae live within a coral polyp, they provide the polyp with extra food and oxygen from their photosynthesis, which the polyp uses to build its skeleton. In exchange, zooxanthellae are given a protected place to live and carbon dioxide from the coral polyp’s respiration. Different zooxanthellae live with different types of corals and come in many different forms and colors. It is the zooxanthellae that give corals their beautiful colors. When corals are stressed, they eject their zooxanthellae, making them look white or bleached; this condition is known as "coral bleaching".
37 3.2 RELATIONSHIPS 4. Lichen – Fungus & Alga / Blue Green Bacterium A lichen is not a single organism but is the result of two or more separate organisms living permanently together. All lichens are made up of a fungus partner and an alga or cyanobacterium partner, or both. Lichens can be many colors (e.g. green, grey, orange and yellow) and can take many intricate shapes and forms.REFERENCES & FURTHER READING- Lichen- Lichen
39 3.3 ECOSYSTEMS & HABITATS 3.3 ECOSYSTEMS & HABITATS 3.3.1 Patchy, Uneven Living SpacesThe ocean is three-dimensional, offering vast living space and diverse habitats from the surface through the water column to the seafloor. Most of the living space on Earth is in the ocean.However, this living space is “uneven”. Certain parts of the ocean are more hostile and difficult to live in than others.Ocean habitats are defined by environmental factors. As a result of interactions between abiotic (i.e. non-living) factors such as salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and circulation, ocean life is not evenly distributed temporally or spatially. In other words, it is “patchy”.For example, parts of the ocean experience seasonal blooms of plankton. This is a time of abundance for predators. However, this period of abundance is only temporary and, for the rest of the year, pickings are much leaner. In order to survive, predators must adapt by changing their diet or migrating to find other prey.Some regions of the ocean, such as coral reefs, support more diverse and abundant life than anywhere on Earth while much of the open ocean is considered a desert.Ocean Literacy Principle 5(e)The ocean is three-dimensional, offering vast living space and diverse habitats from the surface through the water column to the seafloor. Most of the living space on Earth is in the ocean.Ocean Literacy Principle 5(f)Ocean habitats are defined by environmental factors. Due to interactions of abiotic factors such as salinity, temperature, oxygen, pH, light, nutrients, pressure, substrate and circulation, ocean life is not evenly distributed temporally or spatially, i.e., it is “patchy”. Some regions of the ocean support more diverse and abundant life than anywhere on Earth, while much of the ocean is considered a desert.
40 3.3 ECOSYSTEMS & HABITATS ECOSYSTEMS An ecosystem consists of all the living organisms and the non-living things within a specific area. For example, a sandy beach ecosystem consists of all the animals and plants, plus the physical features, such as the sand and the sea.ENVIRONMENT AFFECT ORGANISMSThere are many different types of marine ecosystems, such as rocky beaches, sandy beaches, estuaries, mangroves, coral reefs and kelp forests.In order to fully understand a marine environment, it is important to know not just the biological and behavioural interrelationships between different animals that live in an area but also the physical conditions affecting the environment since both affect an organism’s ability to survive.Interesting!In 3-dimensional space, there are 6 degrees of freedom – up, down, left, right, forward and backward.Humans are used to moving left and right, and forwards and backwards but are less used to moving up and down. In the ocean, moving up and down in the water column is highly important.
41 3.3 ECOSYSTEMS & HABITATS – OCEAN HABITATS 3.3.2 Ocean Habitats & EnvironmentsThe ocean can be divided into a set of habitats or environments (often referred to as ‘eco-regions”) in which life can survive. These are outlined below and are discussed in more detail later.1. COASTSOne of the most difficult habitats in which to live is along the coasts. Tides, waves and predation cause vertical zonation patterns along the shore, influencing the distribution and diversity of organisms. Different life lives in the different environments such as rocky coasts, sandy coasts, and estuaries, with estuaries providing important and productive nursery areas for many marine and aquatic species.2. TROPICAL SEASTropical seas are found between the Tropic of Cancer and the Tropic of Capricorn. Several key environments are found in tropical seas. Mangroves, sea grass beds and coral reefs provide environments for a wide variety of life.3. TEMPERATE SEASTemperate seas lie between the tropics and the polar regions. These are cool green waters that are immensely rich in algae, plant, and animal life.Ocean Literacy Principle 5(g)There are deep ocean ecosystems that are independent of energy from sunlight and photosynthetic organisms. Hydrothermal vents, submarine hot springs, methane cold seeps, and whale falls rely only on chemical energy and chemosynthetic organisms to support life.Ocean Literacy Principle 5(h)Tides, waves and predation cause vertical zonation patterns along the shore, influencing the distribution and diversity of organisms.Ocean Literacy Principle 5(i)Estuaries provide important and productive nursery areas for many marine and aquatic species.
42 3.3 ECOSYSTEMS & HABITATS – OCEAN HABITATS 4. POLAR SEASThe polar seas and regions may be frozen wastelands in many areas but there is also a great deal of contrast and variation in the conditions, and life can and does exist in both the Arctic and Antarctic. In the frozen seas, invertebrates, fish, sea birds and sea mammals abound.5. OPEN OCEANThe open ocean is a virtual desert and, yet, life does live and flourish here. Many open ocean organisms migrate daily from the relative safety of the depths of the ocean to the surface to feed at night before returning to the depths before daylight while other open ocean animals will cross vast tracts of the open ocean in search of food and mates.6. DEEP OCEANIn the ocean trenches and deep ocean, there is no sunlight. In spite of this, there are still deep ocean ecosystems that are independent of energy from sunlight and photosynthetic organisms. Life, including crabs and worms, can live in the deep, dark depths, and survive the searing heat from hydrothermal vents or cold methane seeps, relying solely on chemical energy and chemosynthetic organisms for life. The carcasses of dead whales and other animals that have fallen to the bottom of the ocean also serve to supply food to deep ocean animals, such as hagfishes and deep water sharks.
44 3.4 ACTIVITIES 3.4 ACTIVITIES 3.4.1 Origin Of Life CORE ACTIVITY (a) Divide the class into three groups to draw a series of posters about early Earth during the Precambrian eon and is composed of the following eras: Hadean, Archaean and Proterozoic. Assign an era to each group for investigation using books or the Web. For example, please see:Create a poster for each era, consisting of pictures, drawings and information about the era. For each era include the following:• Era Name & Timeline• Environment & Climate• Key EventsPut up all posters along the classroom wall to get an overall timeline of very early life on earth.
45 3.4 ACTIVITIES For example: PRECAMBRIAN (4,500-543 MYA) HADEAN ARCHAEANPROTEROZOICTimeline4,500-3,800 MYAEnvironmentMolten lavaVolcanoesKey EventsEarth coolsRocks formBy Team 13,800-2,500 MYAMethane, Ammonia, HydrogenToxic to life on Earth today. Water vapour becomes liquidLife first appears on Earth in the Archaean. The oldest fossils date to roughly 3,500 MYA and consist of blue-green bacteria. In fact, all life on Earth for the next 1,000 million years was probably bacterial.By Team 22, MYAOxygen buildup due to blue-green bacteria.Carbon dioxide, nitrogen and ozone levels build up.Atmosphere’s ozone layer formed which screened life from the effects of the Sun’s ultraviolet radiation.About 1,800 MYA, simple eukaryotic cells started appearing.Multi-cellular algae and multi-cellular animals started appearingBy Team 3
46 3.4 ACTIVITIES 3.4.2 Ocean Life CORE ACTIVITY (a) Make a diorama of ocean life.For instructions on constructing a diorama and for templates, please see:
47 3.4 ACTIVITIESInclude as many of the following organisms in the diorama as you can:Algae – e.g. kelpPlants – e.g. sea grassesAnimalsVertebrates (animals with backbones):Fish – e.g. angelfish, groupers, sharks and raysReptiles – e.g. sea turtles, sea snakesBirds – e.g. puffins, penguins, gullsMammals – e.g. sea otters, seals, sea lions, walruses, whales, dolphins, manateesInvertebrates (animals without backbones):Cnidarians – e.g. corals, jellyfishPorifera – e.g. spongesCrustaceans – e.g. shrimps, crabs, lobsters, barnaclesMolluscs – e.g. clams, cockles, mussels, oysters, octopus, squidEchinoderms – e.g. sea stars, sea urchins, sand dollars, sea cucumbers
48 3.4 ACTIVITIES 3.4.3 Classification EXTENDED ACTIVITY (a) Use the Web to lookup the following species:• Whitetip reef shark (Triaenodon obesus)• Green sea turtle (Chelonia mydas)• Emperor penguin (Aptenodytes forsteri)• California sea otter (Enhydra lutris)Pay close attention to the similarities and differences between them. For example, what features are common to a fish and a bird? What are some features that distinguish them from one another? These similarities and differences allow you to classify them into various groups.(b) What features are common to all four species?(c) What are some whitetip reef shark features?(d) What are some green sea turtle features?
49 3.4 ACTIVITIES (e) What are some emperor penguin features? (f) What are some California sea otter features?(g) Fill out the following classification table:Whitetip Reef SharkGreen Sea TurtleEmperor PenguinCalifornia Sea OtterKingdomPhylumClassOrderFamilyGenusSpecies
50 3.4 ACTIVITIESANSWERS(a) Use the Web to lookup the following species:• Whitetip reef shark (Triaenodon obesus)• Green sea turtle (Chelonia mydas)• Emperor penguin (Aptenodytes forsteri)• California sea otter (Enhydra lutris)Pay close attention to the similarities and differences between them. For example, what features are common to a fish and a bird? What are some features that distinguish them from one another? These similarities and differences allow you to classify them into various groups.(b) What features are common to all four species?They are all animals (Animalia)They all have a backbone (Chordata)(c) What are some whitetip reef shark features?It is a cartilaginous fish (Chondrichthyes)As a fish, it has gills and is able to breathe in the waterIt has a body made of cartilage
51 3.4 ACTIVITIES (d) What are some green sea turtle features? It is a reptile (Reptilia)It is cold-blooded (or poikilothermic)It lays eggs and buries them in the sand to keep them warm(e) What are some emperor penguin features?It is a bird (Aves)It is warm-blooded (or homeothermic)It has feathers and a bill or beakIt lays eggs and incubates the eggs to keep them warm(f) What are some California sea otter features?It is a mammal (Mammalia)It gives birth to live youngIt has fur and feeds its young on milk
52 3.4 ACTIVITIES (g) Fill out the following classification table: Whitetip Reef SharkGreen Sea TurtleEmperor PenguinCalifornia Sea OtterKingdomAnimaliaPhylumChordataClassChondrichthyesReptiliaAvesMammaliaOrderCarcharhiniformesTestudinesSphenisciformesCarnivoraFamilyCarcharhinidaeCheloniidaeSpheniscidaeMustelidaeGenusTriaenodonCheloniaAptenodytesEnhydraSpeciesObesusmydasforsterilutris
53 3.4 ACTIVITIES 3.4.4 Adaptation CORE ACTIVITY (a) Study the following drawings of different teeth, jaws, and mouths of various fishes.
54 3.4 ACTIVITIES(b) What does a parrotfish eat? Why are their teeth and jaws well-adapted to what they eat?(c) What does a moray eel eat? Why are their teeth and jaws well-adapted to what they eat?(d) What does a butterflyfish eat? Why are their teeth and jaws well-adapted to what they eat?(e) Why is a moray eel not adapted to eating corals?(f) Why is a butterflyfish not adapted to eating other fish?
55 3.4 ACTIVITIESANSWERS(a) Study the following drawings of different teeth, jaws, and mouths of various fishes.
56 3.4 ACTIVITIES(b) What does a parrotfish eat? Why are their teeth and jaws well-adapted to what they eat?The parrotfish has a parrot-like “beak” from fused teeth and strong jaws to help it bite into rock-hard coral structures and scrape off the algae and corals.(c) What does a moray eel eat? Why are their teeth and jaws well-adapted to what they eat?Morays eels are predators that feed on fishes, octopuses, crustaceans and molluscs. They have long, sharp teeth and powerful jaws that can crush bone.(d) What does a butterflyfish eat? Why are their teeth and jaws well-adapted to what they eat?The foureye butterflyfish have long, pointed mouths for plucking out coral polyps as food. They feed mainly on hard and soft corals (gorgonians), polychaete worms, and tunicates.(e) Why is a moray eel not adapted to eating corals?A moray eel does not have a long, pointed mouth for plucking out coral polyps.(f) Why is a butterflyfish not adapted to eating other fish?A butterflyfish does not have the long, sharp teeth or powerful jaws needed to hunt and kill other fish.
57 3.4 ACTIVITIES 3.4.5 Food Pyramid CORE ACTIVITY (a) Arrange the following organisms in a food pyramid• Plants• Whale sharks• Blue whales• Great white sharks• Phytoplankton• Zooplankton• Sea urchins• Seals• Killer whales• Algae
59 3.4 ACTIVITIES(b) Imagine a blue whale has taken in a mouthful of seawater. What kind of things might be in its mouth? In contrast, what might be in a killer whale’s mouth?(c) Where would you put a human in the food pyramid? Why?(d) Discuss whether you think humans can be considered to be top predators
60 3.4 ACTIVITIESANSWERS(a) Arrange the following organisms in a food pyramid• Plants• Whale sharks• Blue whales• Great white sharks• Phytoplankton• Zooplankton• Sea urchins• Seals• Killer whales• Algae
62 3.4 ACTIVITIES(b) Imagine a blue whale has taken in a mouthful of seawater. What kind of things might be in its mouth? In contrast, what might be in a killer whale’s mouth?Blue whales eat plankton by filtering it from mouthfuls of water. Killer whales are predators and feed on many things including seals, fish and squid.(c) Where would you put a human in the food pyramid? Why?Humans would probably be considered secondary or tertiary consumers although it can be argued that because we hunt and eat many things, we should be at the top of the food pyramid and be considered a quaternary consumer.(d) Discuss whether you think humans can be considered to be top predatorsHumans are a little strange because in some ways we are very much a top predator but in other ways we do not fit the bill at all. We may be considered to be a top predator since we eat many other animals and we are rarely preyed upon. However, humans are probably not true top predators in the sense that we do not have the teeth or predatory abilities other top predators (e.g. sharks, lions, tigers) have. We also routinely have a mixed animal and vegetable (omnivorous) diet in contrast to most top predators which are carnivorous. We are also very numerous compared to other top predators.
63 3.4 ACTIVITIES 3.4.6 Predator-Prey CORE ACTIVITY (a) Draw a line between the predators on the left with their prey on the right to illustrate their predator-prey relationship.
65 3.4 ACTIVITIES(b) One of the animals does not prey on other animals but is a herbivore (an animal that eats plants). Which is it?(c) If a shark eats a tuna, and a tuna eats other fish, which is a predator and which is prey?
66 3.4 ACTIVITIESANSWERS(a) Draw a line between the predators on the left with their prey on the right to illustrate their predator-prey relationship.
68 3.4 ACTIVITIES(b) One of the animals does not prey on other animals but is a herbivore (an animal that eats plants). Which is it?The herbivore is the manatee which eats sea grass(c) If a shark eats a tuna, and a tuna eats other fish, which is a predator and which is prey?An animal can be both predator and prey. A tuna that eats other fish is a predator. However, the tuna is also prey to sharks. Some sharks prey on other sharks so sharks can be both predator and prey. Predators that are not consumed by any other animal (such as Great White Sharks) are known as “top predators”.
69 3.4 ACTIVITIES 3.4.7 Ocean Living Spaces CORE ACTIVITY (a) The ocean is a vast 3-dimensional living space. Where do the following animals live in different parts of the water column?• Sponges• Whale sharks• Sea turtles• Corals• Whales• Sea otters• Humans• Groupers• Flounders• Crabs• ZooplanktonHint: First place the four air-breathing animals at sea-level. Then, find and label the four animals that live on the sea floor. Finally, place the animals that live in the water in the top layer of the ocean.
71 3.4 ACTIVITIES(b) There are 3 dimensions and 6 degrees of freedom? What are those degrees of freedom?(c) Which animals move up and down the water column on a daily basis?
72 3.4 ACTIVITIESANSWERS(a) The ocean is a vast 3-dimensional living space. Where do the following animals live in different parts of the water column?• Sponges• Whale sharks• Sea turtles• Corals• Whales• Sea otters• Humans• Groupers• Flounders• Crabs• ZooplanktonHint: First place the four air-breathing animals at sea-level. Then, find and label the four animals that live on the sea floor. Finally, place the animals that live in the water in the top layer of the ocean.
74 3.4 ACTIVITIESNote there are several possible solutions and it doesn’t really matter whether corals and sponges are reversed for example. What is important is that you would typically see them on the sea floor.(b) There are 3 dimensions and 6 degrees of freedom? What are those degrees of freedom?The 6 degrees of freedom are up, down, left, right, forward and backward.(c) Which animals move up and down the water column on a daily basis?Zooplankton moves up and down the water column. Many fishes and other animals that eat zooplankton follow their daily movement up and down the water column.