Evolution and Life in the Ocean

Transcription

1 Characteristics of All Living Things Contain matter in a highly organized state Capture, store and transmit energy; all organisms require energy Capable of reproduction Change through time and adapt to their environment 1 Evolution and Life in the Ocean Life originated in the ocean. Organisms have evolved over the last 4 billion years through the process of natural selection. The environment favors individuals that are well adapted. Microorganisms are the most successful life forms. Sometimes, catastrophic events wipe out many organisms, regardless of adaptation. 2 1

2 Classification of Oceanic Life Linnaeus developed the system used to name and classify organisms System is based on a hierarchy: kingdom, phylum, class, order, family, genus and species Uses scientific names for organisms; a species consists of the genus name combined with a trivial name. Formal names are in Latin; common names are in local languages 3 Classification of Living Things The six (or five) kingdoms of organisms 4 2

3 The Three Domains of Life 5 Classification of Oceanic Life 6 3

4 7 Classification of the Marine Environment 8 4

5 9 Benthic (bottom) and Pelagic (water column) Environments Benthic environment - divided by depth into: intertidal zone, sublittoral zone, bathyal zone, abyssal zone, and the hadal zone. Pelagic environment - divided broadly into: neritic zone and oceanic zone, and more specifically into the epipelagic, mesopelagic, bathypelagic, abyssalpelagic, and hadalpelagic zones. 10 5

6 Zones Based on Depth of Light Penetration Photic zone - depth where light is sufficient for photosynthesis. Dysphotic zone - illumination is too weak for photosynthesis. Aphotic zone - no light from the surface because it is all absorbed by the water above. 11 Major Lifestyles Plankton - free floating organisms; phytoplankton and zooplankton Nekton - swimmers Benthos - bottom dwellers (on, in or attached) Epifauna - live on the bottom (attached or free) Infauna - organisms that live in or burrow in the sediment 12 6

7 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 describes organisms that have narrow tolerances for specific factors Eury- is a prefix meaning wide. It describes organisms that have wide tolerances for specific factors 13 Limiting Factors Limiting factor - physical or chemical factor in the environment that can limit or harm organisms if present at levels that are too large, too small or too extreme. Any factor required for life can become a limiting factor. 14 7

8 Physical Factors Affecting Marine Life Any aspect of the physical environment that affects organisms is a physical factor. The most important physical factors for marine organisms are: light temperature salinity nutrients dissolved gases acid-base balance hydrostatic pressure buoyancy 15 Figure

9 Temperature Temperature - controls distribution, degree of activity and reproduction of an organism Ectotherms - cold-blooded organisms; body temperature determined by environmental conditions (all marine organisms except birds and mammals) Endotherms - warm-blooded organisms; maintain near-constant body temperature (birds and mammals) 17 Temperature 18 9

10 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 19 Figure

11 Physical Factors Affecting Marine Life 21 Biological Factors Biological factors also affect organisms in the ocean. Some biologic factors that affect marine organisms: feeding relationships crowding metabolic wastes defense of territory 22 11

12 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. 23 Diffusion, Osmosis, and Active Transport 24 12

13 Marine Ecology Ecology: Inter-relationships between the physical and biological aspects of the environment Marine organisms live in communities - groups of interacting producers, consumers, and decomposers sharing a common living space Ecosystem - total environment including the biota (all living organisms) and the non-living physical and chemical aspects Symbiotic relationships are common in the ocean. Most forms of marine life are actively involved in them 25 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 26 13

14 Symbiotic Interactions Symbiosis is the close interaction of the lives of two species. Types of symbiotic interactions: Mutualism - both organisms benefit in these relationships. Commensalism - one organism benefits, the other is not helped or harmed. Parasitism - one organism benefits, but the other is harmed. 27 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

15 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. 29 Competition Competition can occur among members of the same species, or between members of different species

16 Examples of Marine Communities Rocky intertidal Seaweed Beach Salt marsh and estuary Coral reef Open ocean Deep sea floor Hydrothermal and cold vents 31 Intertidal Communities Generally arranged in distinctive bands or vertical zonation Zonation reflects amount of time the area is submerged and ability of organisms to survive exposure. Benthic communities also vary based on substrate (bottom material). Some organisms are adapted to rocky, sandy, or muddy sea bottoms

17 HIGH TIDE LOW TIDE 33 Rocky Intertidal Communities The most important physical factor in a rocky intertidal community is the34 rise and fall of tides. 17

18 Seaweed Community Seaweed provides protection and high productivity to the animals that live in the communities A complex interaction among kelp, sea urchins, and sea otters controls the kelp community Sea urchins feeding on kelp detach them from their holdfast and devastate the kelp beds Sea otters feed on sea urchins and control the size of their population Where sea otters abound, sea urchins are few, kelp beds thrive and sea otters feed mainly on fish. Where sea otters are few, sea urchins abound and kelp bed are thin. Sea otters then mainly eat sea urchins. 35 Sand and Cobble Beach Communities Beaches are a demanding physical environment for organisms

19 Salt Marshes and Estuaries Salt marshes and estuaries are rich in nutrients, but organisms must cope with fluctuating salinity in these environments. 37 Coral Reefs More than one million species inhabit coral reef ecosystems

20 Open Ocean Consumers in the open ocean depend on the productivity of organisms in the water column above. 39 The Deep-Sea Floor The deep-sea floor is dark, cold, and highly pressurized, yet many species including the blind tripod fish are found in this harsh environment

21 Hydrothermal Vent and Cold Seep Communities Many chemosynthetic organisms are found near hydrothermal vents and cold seeps. 41 A Pacific coast tide pool. Organisms rely on both the physical and biological factors in their environment for survival