NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
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Nekton: Free Swimmers of the Sea
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Notes on Topic:
The notes represent summaries of key issues
for each topic
They emphasize the terminology used to describe
the various phenomena.
| 1. Characteristics of Nekton: |
| Learning Objectives: |
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Comprehension of habitats and lifestyle of nekton
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Understanding of characteristics and feeding strategies of nekton
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| Marine Mammals: |
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Warm-blooded, air-breathing, include herbivores
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Cetaceans: whales, dolphins, porpoises
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baleen whales filter feed on phytoplankton
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includes most great whales
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toothed whales eat fish, or crustacea
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some whales are migratory (grey whale, humpback)
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whale explotation and harvesting 'til moratorium
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use echo-location to locate prey
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high and low frequency clicks emitted
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Pinnipeds:
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seals, walruses, sea lions with flippers
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Others:
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sea otters; sea cows (manatees, dugongs)
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| Seabirds: |
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Nest on land, near ocean food source
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Variety of lifestyles and foods;
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wading: (herons, egrets)
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diving: pelicans, cormorants
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oceanic: albatross, petrels
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swimming: penguins (flightless)
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| Marine Reptiles: |
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Sea turtles:
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herbivores that live in the ocean
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nest on land, migratory
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Others:
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sea snakes and lizards (marine iguanas, Galapagos)
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| Squid: |
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Live at mid-depth and migrate to surface at night
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most 10cm -1m; giant squid, eaten by sperm whales (up to 18m)
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swim by expelling water through a funnel
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use tentacles to catch small fish as their prey
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| Fish: |
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Cartilaginous fish:
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sharks:
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scavengers, feeding on fish, seals, especially weak individuals
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plankton feeders: basking shark, whale shark
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primitive animals with cartilage not bone skeletons
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plates (denticles) not scales
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rays, mainly carnivores, except manta ray: a herbivore
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Bony fish:
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fish body shapes:
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allow rapid movement, reduce drag
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minimized in fusiform body
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swim by series of body waves
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moving from head to tail, accelerating water
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shapes reflect lifestyles and feeding strategies:
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demersal:
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on ocean floor include cod and flatfishes
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open-ocean:
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include tuna and mackerel, salmon, trout in colder waters
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Vision Underwater:
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foggy medium, from light scattering by particles
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light gets dimmer with depth, large-eyed fish
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Deep Ocean Nekton:
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predators, live in cold, dimly lit ocean
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often bioluminescent
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may use lures, e.g. angler fish.
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| Herring and Cod: |
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Herring, include sardines, anchovies:
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fast growing, larval stage spent in estuaries
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swim with open mouths
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depletion of larger fish by heavy fishing reduces spawning
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Cod:
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once abundant in mid-/high latitudes of N. Hemisphere
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overfished, fisheries closed in 1992
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| Migrations: |
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Predictable movement of animals
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anadromous:
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salmon, spawn and grow in freshwater
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catadromous:
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eels
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spawn in Sargasso Sea
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return to coastal waters when mature
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added by magnetic compass?
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Department
of Geological Sciences,
1001
E. Tenth Street, Bloomington, IN 47405-1403
Phone:
(812) 855-5582 Last updated: 7 December 2000
Comments:
simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
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