Evolution and Life in the Ocean

Characteristics of All Living Things • contain matter in a highly organized state • can capture, store and transmit energy • are capable of reproduction • can change through time and adapt to their environment 1 Evolution and Life in the Ocean Earth’s organisms have changed, or evolved, over the course of 4 billion years. Evolution occurs through the process of natural selection. The environment favors individuals that are well adapted. Their favorable traits are retained because they contribute to the organism’s reproductive success. 2 1 Classification of Oceanic Life Living things on Earth share many characteristics. Linnaeus developed some of the systems used to name and classify organisms. • One of the first to use a system of natural classification • Developed a classification system based on hierarchy • Developed a system of scientific names for organisms 3 The Three Domains 4 2 Classification of Living Things The six kingdoms of living things 5 Classification of Oceanic Life 6 3 Major Groups l Plankton - free floating organisms l Nekton - swimmers l Benthos - bottom dwellers (on, in or attached) l Epifauna - live on the bottom (attached or free) l Infauna - organisms that live in or burrow in the sediment 7 Classification of the Marine Environment The marine environment is divided into zones - areas with homogeneous physical features. Zones are classified by location and the behavior of the organisms found there. 8 4 9 Classification of the Marine Environment 10 5 Limiting Factors Limiting factor - factor found in the environment that can be harmful if present in quantities that are too large or too small. Any factor required for life can become a limiting factor. 11 Physical Factors Affecting Marine Life Any aspect of the physical environment that affects living organisms is a physical factor. The most important physical factors for marine organisms are: light dissolved gases temperature acid-base balance salinity hydrostatic pressure dissolved nutrients buoyancy 12 6 Figure 13.8 13 Figure 13.9 14 7 Physical Factors Affecting Marine Life 15 Body Temperatures l Ectotherms - cold-blooded organisms; body temperature determined by environmental conditions (all marine organisms except birds and mammals) l Endotherms - warm-blooded organisms; maintain near-constant body temperature (birds and mammals) 16 8 Organisms and Ocean Together Biological factors also affect organisms in the ocean. Some biologic factors that affect ocean organisms: • feeding relationships • crowding • metabolic wastes • defense of territory 17 Diffusion, Osmosis, and Active Transport Organisms in the ocean rely on these processes for many life functions. Diffusion is mixing due to random molecular movements. Osmosis is diffusion of water through a membrane Active transport is the transport of a substance against a concentration gradient. Active transport requires energy input. 18 9 Diffusion, Osmosis, and Active Transport 19 Biogeochemical Cycles Cycles of elements that are important in life processes. Carbon - present in all organic molecules Nitrogen - found in proteins and nucleic acids Phosphorus and silicon – found in rigid parts of organisms Iron and trace metals - used for electron transport 20 10 Carbon Cycle 21 Marine Communities The J-shaped curve represents the growth of a population without competitors for food or space. The S-shaped curve represents population growth when the population encounters environmental resistance. 22 11 Marine Ecology * Marine organisms are found in communities, groups of interacting producers, consumers, and decomposers that share a common living space. * The organisms found in a particular community depend on the physical and biological characteristics of the living space. * Symbiotic relationships are common in the ocean. Most forms of marine life are actively involved in them. 23 Organisms Within Communities Terms for describing organisms and their environments: Habitat - an organism’s physical location in its community Niche - an organism’s role in the community Biodiversity - the variety of species in a given area 24 12 Physical and Biological Factors A proper balance of physical and biological factors is important for the success of each organism and the community. Different organisms have different tolerances for specific factors. Steno- is a prefix meaning “narrow”. It can be used to describe organisms that have narrow tolerances for specific factors Eury- is a prefix meaning “wide”. It can be used to describe organisms that have wide tolerances for specific factors 25 Physical and Biological Factors 26 13 Changes in Marine Communities Marine communities change through time. Changes can occur slowly due to climate cycles or seafloor spreading, or quickly due to factors such as volcanic eruption. A climax community is a stable, long established community. If a climax community is disrupted, it may be restored through the process of succession. 27 Examples of Marine Communities l Rocky intertidal l Seaweed l Beach l Salt marsh and estuary l Coral reef l Open ocean l Deep sea floor l Hydrothermal and cold vents 28 14 Rocky Intertidal Communities The most important physical factor in a rocky intertidal community is the29 rise and fall of tides. Seaweed Communities Seaweed provides protection and high productivity to the animals that live in seaweed communities. 30 15 Salt Marshes and Estuaries Salt marshes and estuaries are rich in nutrients, but organisms must cope with fluctuating salinity in these environments. 31 Hydrothermal Vent and Cold Seep Communities Many chemosynthetic organisms are found near hydrothermal vents and cold seeps. 32 16 Symbiotic Interactions Symbiosis is the close interaction of the lives of two species. Types of symbiotic interactions: Mutualism - both organisms benefit in these relationships. An example is sea anemones and anemone fish. Commensalism - one organism benefits, the other is not helped or harmed. Parasitism - one of the organism benefits, but the other is harmed. 33 17.

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