Garrison Oceanography 7e Chapter 15

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Oceanography An Invitation to Marine Science,
7th Tom Garrison
Chapter 15 Marine Animals
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Chapter 15 Study Plan

• Animals Arose Near the End of the Oxygen
  Revolution
• Invertebrates Are the Most Successful and
  Abundant Animals
• The Worm Phyla Are the Link to Advanced Animals
• Advanced Invertebrates Have Complex Bodies and
  Internal Systems
• Construction of Complex Chordate Bodies Begins on
  a Stiffening Scaffold
• Vertebrate Evolution Traces a Long and Diverse
  History
• Fishes Are Earths Most Abundant and Successful
  Vertebrates
• Fishes Are Successful because of Unique
  Adaptations
• Sea Turtles and Marine Crocodiles Are Ocean-Going
  Reptiles
• Some Marine Birds Are the Worlds Most Efficient
  Flyers
• Marine Mammals Include the Largest Animals Ever
  to have Lived

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Chapter 15 Main Concepts

• Animals could not evolve until atmospheric oxygen
  was abundant. Photosynthetic autotrophs (mainly
  cyanobacteria) changed the composition of the
  atmosphere during the oxygen revolution.
• More than 90 of all living and fossil animals,
  including all of the earliest multi-cellular
  animals, are invertebrates animals without
  backbones.
• By nearly any criterion, arthropods a group
  that includes lobsters, shrimp, crabs, and
  insects are the most successful of Earths
  animals.
• The Chordates possess a stiffening scaffold a
  notochord on which they are constructed. In
  vertebrate chordates, this structure persists as
  a vertebral column.
• Fishes are Earths most abundant and successful
  vertebrates.
• Marine mammals include the whales, the largest
  animals ever to have lived on Earth.

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Animals Arose near the End of the Oxygen
Revolution

• During the oxygen revolution (2 billion to 400
  million years ago), photosynthetic autotrophs
  mostly bacteria caused a rapid rise in the
  amount of oxygen in the air, which made possible
  the evolution of animals. Animals are thought to
  have arisen between 900 and 600 million years ago.

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Phylum Porifera Contains the Sponges

• The body plan of a simple sponge.

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Water out
Central cavity
Water in
Collar cell
Stepped Art
Fig. 15-3b-d, p. 406
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Stinging Cells Define the Phylum Cnidaria

• Anatomy of a reef coral polyp, with enlarged
  detail showing a cross section of the outer
  covering and tissue. The symbiotic photosynthetic
  zooxanthellae are crucial to the survival of this
  type of coral.

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Advanced Invertebrates Have Complex Bodies and
Internal Systems

• Bivalves are suspension feeders that make their
  living by filtering the water for edible
  particles. In this diagram (showing a bivalve
  with its left shell removed), water and tiny bits
  of food are swept into the animal by the movement
  of tracts of cilia on the gills. Food settles
  onto the gills and is then driven toward the
  mouth and swallowed.

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Sea Stars Are Typical of the Phylum Echinodermata

• The water-vascular system in a sea star (shown in
  blue). (a) Water enters the animals body through
  a sieve plate, which excludes material that might
  clog the tubes and valves, and circulates through
  canals.

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Construction of Complex Chordate Bodies Begins on
a Stiffening Scaffold

• Chordata is the most advanced animal phylum. All
  chordates have, at some time during development,
  a notochord. Both invertebrate and vertebrate
  chordates are represented in ocean environments.
• In some chordates the notochord is lost during
  development. These are the invertebrate
  chordates.
• Most chordates (about 95) retain the notochord
  in some form. These are the vertebrate chordates.

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Vertebrate Evolution Traces a Long and Diverse
History

• One proposed family tree for the vertebrates and
  their relatives, the invertebrate chordates.

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Class Osteichthyes Comprises the Familiar Bony
Fishes

• About 90 of all living fishes are contained
  within the osteichthyan order Teleostei, which
  contains the cod, tuna, halibut, goldfish, and
  other familiar species.
• (left) Some of the diversity exhibited by teleost
  (bony) fishes. These fishes are not all drawn to
  the same scale.

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Fishes Are Well Adapted to Their Environment

• What are some problems posed by living in a
  marine environment?
• Movement, shape and propulsion - fish must be
  able to move through water, which is 1,000 times
  denser and 100 times more viscous than air
• Maintenance of level - fish tissue is usually
  denser than the surrounding water, so fish must
  have a system to keep from sinking
• Gas exchange - the problem of extracting oxygen
  from water
• Osmotic considerations - fish need a system to
  maintain proper salt levels in their bodies
• Feeding and defense - competitive pressure among
  a large number of fish resulted in the evolution
  of a wide variety of feeding habits

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Fishes Are Well Adapted to Their Environment

• Turbulence and drag. At the same speed, with the
  same frontal area, shape (a) will have about 15
  times as much drag as shape (c). Shape (b) shows
  only a small improvement in drag over the disk.

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Gas Exchange Is Accomplished through Gills

• Cutaway of a mackerel, showing the position of
  the gills (a). Broad arrows in (b) and (c)
  indicate the flow of water over the gill
  membranes of a single gill arch. Small arrows in
  (c) indicate the direction of blood flow through
  the capillaries of the gill filament in a
  direction opposite to that of the incoming water.
  This mechanism is called countercurrent flow.

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Successful Fishes Quickly Adapt to Their Osmotic
Circumstances

• Osmoregulation in freshwater and marine fishes.

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Like All Birds, Marine Birds Evolved from
Dinosaur-Like Ancestors

• Only 270 of the known species of birds qualify as
  seabirds. Seabirds have salt excreting glands to
  eliminate salt taken in with their food.
• There are four groups of seabirds
• Tubenoses - this group includes the albatrosses
  and petrels
• Pelicans - this group includes relatives of the
  penguins that have webbed feet and throat pouches
• Gulls - these birds are found along the shore,
  where they scavenge for food.
• Penguins - these birds have lost the ability to
  fly, but are excellent swimmers

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Marine Mammals Share Common Features

• What are the three groups of marine mammals?
• Cetacea porpoises, dolphins and whales
• Carnivora - seals, sea lions, walruses and sea
  otters
• Sirenia manatees and dugongs

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Marine Mammals Share Common Features

• A few of the marine mammals of the Order Cetacea.
  Suborder Mysticeti (mystidos unknowable)
  whales are known for having no teeth and instead
  use baleen for filter feeding.

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Marine Mammals Share Common Features

• Some representatives of the order Cetacea.
  Suborder Odontoceti (odontos tooth) whales are
  known for being active predators who use teeth
  for feeding. The toothed whales search for food
  using echolocation, a biological equivalent to
  sonar.

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The Order Cetacea Includes the Whales

• Marine animals have evolved effective adaptations
  for capturing prey, avoiding danger and
  maintaining thermal and fluid balance with their
  environment.
• (above) Echolocation, used by toothed whales to
  locate and perhaps stun their prey.

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The Order Cetacea Includes the Whales

• A plate of baleen and its position in the jaw of
  a baleen whale. For clarity, the illustration
  shows an area of the mouth cut away.

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Chapter 15 in Perspective

• In this chapter you learned that animals must
  ultimately depend on primary producers
  (autotrophs) for nutrition. Animals could not
  exist on Earth until increasing levels of free
  oxygen in the atmosphere permitted them to
  metabolize food obtained from autotrophs. And
  remember, it was the photosynthetic autotrophs
  themselves that contributed huge quantities of
  oxygen to the environment. True multi-cellular
  animals arose between 900 and 700 million years
  ago, near the end of this oxygen revolution.
  Their variety is astonishing a tribute to
  millions of years of complex interplay between
  environment, producer, and consumer.
• Our survey of marine animals followed the course
  of their evolution. The complexity of animals
  increased as we moved from groups (phyla) whose
  basic structure seems to have solidified
  relatively early in the history of animals to
  groups that evolved more recently. Every marine
  animal has evolved effective adaptations for
  capturing prey, avoiding danger, maintaining
  thermal and fluid balance with their
  surroundings, and competing for space, and our
  survey of marine animals stressed these
  adaptations.
• In the next chapter you will learn how these
  animals interact with one another and with their
  environment. The organisms you met in the last
  two chapters do not live alone. They are
  distributed throughout the marine environment in
  specific communities groups of interacting
  producers, consumers, and decomposers that share
  a common living space. The types and variety of
  organisms found in a particular community depend
  on the physical and biological characteristics of
  that living space.