Transcript Garrison Oceanography 7e Chapter 15

Oceanography
An Invitation to Marine Science, 7th
Tom Garrison
Chapter 15
Marine Animals
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.
Animal Phylums
Porifera overview
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Simplest animals
Assymetrical
No tissues or organs
Sessile
Filter feeders
Sexual/asexual
reproduction
Phylum Porifera Contains the
Sponges
The body plan
of a simple
sponge.
Water out
Spicules
Amoeboid
cell
Pore
Mesoglea
Central
cavity
Flattened
surface
cells
Flagellum Microvilli
Nucleus
Water in
Collar cell
Stepped Art
Fig. 15-3b-d, p. 406
Phylum Cnidaria
•Radial symmetry
•Two forms: polyp & medusa
•3 layers: gastroderm & epidermis,
and mesoglea
•Gastrovascular cavity
•Stinging cells (nematocysts)
•Primitive nerve net
Cnidarian forms
• Polyps are often
sessile forms.
• Medusa are mature
free swimming forms.
Cnidarian Classes
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Scyphoza- true jellyfish
Hydroza- Portuguese Man of war
Anthoza- anemones, coral
Cubozoa- box jellyfish
Platyhelminthes
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Flatworms
Bilateral symmetry
A head
Parasitic or free living
A central nervous sys.
Platyhelminthes cont.
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No respiratory system
Hermaphrodites
Examples:
Leeches, planaria,
liver fluke, tapeworms
Nematodes
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Roundworms
Terrestrial/marine
12,000 species
Free living/parasitic
Mouth and anus
1 way digestion
Nematodes continued
• Examples:
• Ascarids, filarias,
hookworms, pinworms,
• Heartworms, etc.
Heartworm lifecycle
Annelids
•Segmented worms
•17,000 species
•Bilateral symmetry
•Primitive heart, blood circulatory system
•Septa enable movement
•Great Earth movers
Annelids varieties
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Polychaetes- marine worms
Bristleworms
Ragworms
Earthworms
Tubeworms
Mollusks Have Complex Bodies and
Internal Systems
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Second largest phylum invertebrate 80 K species.
They can be marine or terrestrial.
Mollusks have bilateral symmetry
Examples are: Clams, snails, octopus, & squid.
Classes of Mollusks
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Gastropods: examples include snails, conch, abalone
The largest class of mollusks.
Soft bodies, are most often in shells.
Most feed off the bottom using a radula (raspy tongue).
The foot enables it to glide along a surface.
Classes of Mollusks cont…
• Bivalves (two shells) include clams, oysters,
mussels, and scallops
• Have some mobility.
• Cephalopods include squid, octopus, and
cuttlefish.
• Most intelligent of all invertebrates
• Have tentacles, and a sharp beak
• Have the ability to eject ink, and camouflage
themselves.
Phylum Mollusca
Characterictics of the Phylum Echinodermata
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Echinoderm means “spiny skin”
The exhibit radial symmetry.
They are confined to the marine environment.
They have an internal “skeleton”.
The only phylum with a water vascular system
They have cup-like structures called tube feet.
They are capable or regenerating body parts.
Echinoderms continued…
• The water vascular system allows for
movement, respiration, and circulation.
• The Starfish digests it’s food externally.
• Their skeleton consists of hard plates.
• Their nervous system is highly developed.
Classes of Echinoderms
• Sea urchins and sand dollars- have large solid
plates that encase them.
• Brittle stars- have long slender arms and are
filter feeders.
• Sea cucumbers- are soft and capable of
extruding their organs at predators.
• Sea stars- are capable of regeneration
(as long as a part of the central body is present)
Echinoderms
Here Come the Arthropods
• Most numerous animal phylum, 750,000 species
• Examples include: insects, spiders, centipedes,
and crabs.
• Characteristics include: an exoskeleton, jointed
appendages, and a segmented body.
• Their systems are advanced.
• Notable are the way they develop:
– Some go through metamorphosis
– Some molt as they grow
Molting
Arthropod Classes
Crustaceans
• These are the marine arthropods
• They typically have: 2 pairs of antennae.
2-3 body sections, and a mandible (for chewing)
Examples : crayfish, shrimp, crabs, and barnacles
Horseshoe and spider crabs are not crustaceans.
Chordates begin with a Notochord
• Chordata- the most advanced animal phylum. All
chordates have, at some time during development,
a notochord. Invertebrate and vertebrate chordates
are present in ocean environments.
• Invertebrate chordates lose their notochord during
development.
• Most chordates (about 95%) retain the notochord in
some form. These are the vertebrate chordates.
Vertebrate Evolution Traces a
Long and Diverse History
One proposed family tree for the vertebrates and
their relatives, the invertebrate chordates.
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.
Fishes Are Well Adapted to Their
Environment
• Movement, shape and propulsion - fish must be able to move
through water, which is 1,000 times denser and 100 times than air
• Maintenance of level - fish are usually denser than water, so fish
must have a system to keep from sinking. (swim bladder)
• 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 - competition among a large number of fish
resulted in the evolution of a wide variety of feeding habits.
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.
Successful Fishes Quickly Adapt
to Their Osmotic Circumstances
Osmoregulation in freshwater and marine fishes.
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.
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
Marine Mammals Share Common
Features
A few of the marine
mammals of the Order
Cetacea, are known for
having no teeth and
instead use baleen for
filter feeding.
Marine Mammals Share Common
Features
Some Cetaceans,
Suborder Odontoceti
(odontos = tooth) are
known for being active
predators. The
toothed whales
search for food using
echolocation, a
biological equivalent
to sonar.
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.
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.