Transcript Life on an Ocean Planet

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►The Linnaeus Classification System
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►Prokaryotes-Small yet Significant
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►Marine Algae
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►Marine Plants
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►Sponges-Filters of the Sea
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►Corals, Anemones, Sea Fans, and Jellies ►
►Simple Marine Worms
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►Mollusks-A Bag, a Scraper, and a Foot
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►Complex Worms
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Crustaceans-Underwater Arthropods
Echinoderms-Stars of the Sea
Invertebrate Chordates
Vertebrate-Top of the Food Web
Sharks and Rays-Teeth and Wings
Bony Fish-Half the World’s Vertebrates
Marine Reptiles-Cold Blood and Warm
Water
Seabirds-At Flight Over and In the Ocean
Marine Mammals-Warm Blood in Cold
Water
A Survey of Life in the Sea
 It’s not hard to imagine how difficult it would be for scientists to discuss biological
questions without a classification system for life.
 Three reasons for classifying organisms:
Chapter 5 Page 5-4
The Linnaeus Classification System
The Need for Classification
 1. It helps identify the relationships between organisms.
 2. It requires scientists to clearly identify
key characteristics of each organism.
 3. It avoids confusion. Common names differ
with cultures. Scientists in the US
and Japan can identify exactly what they
are both talking about by using the
species’ Latin name.
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Classification Taxa
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An organism’s scientific name represents two taxa. They are:
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Chapter 5 Pages 5-5 to 5-7
The Linnaeus Classification System
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1. Species – is the most specific of the taxa. Species is usually considered to be a group of
organisms that can reproduce together.
2. Genus – is the taxon above species. Genus grouped species are considered to be closely related,
i.e., there are 34 species of reef shark belonging to genus Carcharhinus.
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Species are identified by referring to both the genus and the species, with the genus
capitalized and the species name in lower case.
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There are seven main taxa into which organisms
are classified; from the general to specific:
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1. Kingdoms are groups of phyla (plural of phylum).
2. Phylum (or division) is a group of classes.
3. Classes are groups of related orders.
4. Orders are groups of related families.
5. Families are groups of genera that share characteristics.
6. Genus (plural genera) groups species that are closely related.
7. Species is the Latin name for an individual organism.
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Determining Taxa
 How organisms are classified:
 Originally by using anatomical features.
 The prevailing view now is that taxonomy generally reflects theoretical
evolutionary relationships.
Chapter 5 Pages 5-8 & 5-9
The Linnaeus Classification System
 Classifying by anatomical features remains an important classification method.
However, the study of genetics has become more important.
 A common problem taxonomists have in
classifying organisms is that
some organisms don’t fit neatly into
defined classifications. An organism can
have characteristics that fit in one and others
that separate it from that same classification.
 The answer is to insert intermediate classification levels.
 By assigning superlevels to create new higher divisions within a classification.
 By assigning sublevels to create lower divisions within a classification.
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Six - Kingdom System and
Three - Domain System
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Until recently taxonomists recognized five
kingdoms: kingdom Monera, kingdom Protista,
kingdom Fungi, kingdom Plantae, and kingdom
Animalia.
The six-kingdom system divides kingdom Monera
into two new kingdoms: kingdom Eubacteria and
kingdom Archaebacteria.
The three-domain system method is based on
genetic and biochemical research.
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Chapter 5 Page 5-10
The Linnaeus Classification System
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© Current Publishing Corp. 2006
Domain Archaea is composed of organisms
scientists think evolved first.
In this system domain Eukarya includes the Protista,
Plantae, Fungi and Animalia kingdoms.
Taxa tree
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Old and Simple
Chapter 5 Page 5-12
Prokaryotes – Small yet Significant
 Prokaryotes are among the most important
of the primary producers in the ocean.
 They don’t have the same complex internal
membrane structure.
 They lack chromosomes or a nucleus. Instead
they have a ring of DNA or RNA.
 They don’t have mitochondria and
lack chloroplasts.
 They are structurally simple – molecules
are surrounded by a membrane and cell wall.
 They are believed to be the oldest types of
organisms – archaea originated
3.5 billion years ago.
 Scientists think that the process of
photosynthesis began with cyanophytes
of domain Bacteria, an early prokaryote.
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Archaea and Bacteria
 Domain Archaea and domain Bacteria are best known for being
extremophiles – living in environments that are inhospitable to most life.
 Bacteria can do things no other known organisms can do:
 The most important bacteria are in the phylum Cyanophyta. Scientists think that
these bacteria are crucial to life because:
Chapter 5 Pages 5-13 to 5-15
Prokaryotes – Small yet Significant
 Certain species can create organic nitrogen compounds by fixing inorganic nitrogen
from the air – an essential element of life.
 Photosynthesis evolved in the cyanophytes.
 Cyanophytes were the primary organisms that created the oxygen in
the atmosphere.
 Cyanophytes are among the bacteria responsible for nitrogen fixation.
 Also, some scientists think we presently underestimate the role cyanophytes
play in primary productivity. Their pigments can contribute to the color of
other organisms.
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A Broadly Applied Name
 Algae is defined by taxonomists as those organisms that belong
in one of seven specific phyla or divisions in kingdom Protista.
1. Chlorophyta
2. Rhodophyta
3. Phaeophyta
4. Dinophyta
5. Bacillariophyta
6. Euglenophyta
7. Chrysophyta
Chapter 5 Pages 5-16 & 5-17
Marine Algae
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Phylum Bacillariophyta – The Diatoms
Chapter 5 Pages 5-17 & 5-18
Marine Algae
 Phylum Bacillariophyta is made up of diatoms, the most productive
phytoplankton.
 These primary producers are a widely
diverse group.
 Between 5,000 to 50,000 species may
make up this phylum.
 Diatoms are larger than prokaryotes
– from 20 to 80 microns across.
 They have two-part silicon shells in
an amazing array of shapes.
 They are photosynthesizers that are
relatively dormant during the winter
months.
 Diatoms reproduce quickly when
sunlight levels rise and are thought
to account for 25% of all the photosynthetic biomass on Earth.
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Phylum Dinophyta – The Dinoflagellates
 Dinoflagellates make up phylum Dinophyta (also called phylum
Pyrrophyta or phylum Dinoflagellata).
 In size they are 30 to 150 microns across and
are the second most productive group of
primary producers.
Chapter 5 Page 5-19
Marine Algae
 Symbiodinium are particularly important
autotrophic dinoflagellates.
 They live within the zooxanthellate
coral polyps.
 They provide their host with food via
photosynthesis.
 In return Symbiodinium get nitrogenous
wastes from the coral.
 These are the only coral that build massive coral reefs.
 Without Symbiodinium, coral could not exist as we know it.
 Without coral and coral reefs there would not be the unique organisms that
make up the world’s most productive and beautiful ecosystems.
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Phylum Chlorophyta – Green Algae
 Phylum Chlorophyta is made up of the macro
algae – a term that applies to several algae phyla,
but refers to multicellular species like seaweed.
 They share the same green color as land plants.
Both green algae and land plants have:
Chapter 5 Pages 5-20 & 5-21
Marine Algae
 Chlorophyll a – a pigment directly involved
with photosynthesis.
 Chlorophyll b – assists chlorophyll a in capturing light
for use in photosynthesis.
 Chlorophyll a and b absorb different colors of light, thus using light more efficiently.
 Scientists think the presence of chlorophyll a and b has evolutionary significance. It may
indicate that land plants evolved from green algae.
 Green algae and land plants also have other pigments in common and have cell walls made of
cellulose.
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Phylum Rhodophyta – Red Algae
 Red algae is red because they have pigments called phycoerythrins
which give it their color.
 This pigment has not been found in any other eukaryote, though it does exist in
cyanophytes.
 Phycoerythrins allow some red algae
to live deeper than any other algae –
some as deep as 200 meters (656 feet).
Chapter 5 Pages 5-21 & 5-22
Marine Algae
 Red algae also has chlorophyll a, but not b.
 Red algae is important to coral reefs
because it is the cement that holds
the coral reefs together.
 Red algae species that live on coral reefs
secrete a calcium carbonate shell.
 Their secretions bond coral colonies and debris
together which in turn holds the reef together.
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Phylum Phaeophyta – Brown Algae
 Phylum Phaeophyta (brown algae), is more structurally complex. Many
brown algae species have:
 Holdfasts – anchor the algae to the bottom.
 Leathery stipes – provide support like plant
stems, but with no vascular system.
 Blades – equivalent of leaves.
 Pneumatocysts – gas filled float structures
that lift the algae off the bottom and keep the
blades close to the surface and sun.
Chapter 5 Pages 5-23 & 5-24
Marine Algae
 Kelp is the largest of the brown algae.
 Kelp is important because it is the foundation for
many temperate coastal ecosystems.
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Plant Adaptation to the Marine Environment
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Salinity in the water is the greatest challenge to which plants must adapt.
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Salt causes dehydration in plants.
Marine plants resist dehydration through several adaptations such as waxy coverings or other
protection that reduces water loss and prevention of dehydration.
Submergent and Emergent Plants
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Chapter 5 Pages 5-26 to 5-28
Marine Plants
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Submergent plants live entirely underwater – seagrasses for example.
Emergent plants live with their roots underwater, but with a significant portion of the plant
growing above the surface – mangroves for example.
Other than producing food and oxygen, marine plants provide important habitats for other
marine organisms.
Mangrove swamps are important to the environment:
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1. They act as nurseries for adjacent marine ecosystems.
2. They filter runoff water protecting sensitive offshore ecosystems that would be harmed or killed by
settling sediment.
3. They hold sediments in place. They slow waves and reduce erosion while retaining nutrients used
by organisms living there.
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Characteristics of Sponges
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Like all members of phylum Porifera, sponges aren’t very animal-like.
Besides being multicellular heterotrophs, they have structural
organization and different cell types.
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Sponges are filter feeders – the amoebocytes distribute
nutrients throughout the sponge.
Special Attributes of Sponges
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Chapter 5 Pages 5-30 to 5-32
Sponges – Filters of the Sea
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1. Collar cells have flagella that waft water into the sponge’s
epithelium (a tissue that protects the outer surface).
2. Amoebocytes (second cell type) pick up nutrient particles
as the water flows through the sponge walls.
Sponge larvae are more animal-like than adult sponges because they are free-swimming
organisms with flagella.
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The larvae swim and drift until they fix themselves in place on the reef and grow into adult sponges.
Most sponges are tough and fibrous, many produce toxic defense chemicals.
After being torn apart, remaining pieces in contact may grow together.
Isolated pieces can regenerate into entirely new sponges.
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Characteristics of Phylum Cnidaria
Chapter 5 Pages 5-33 & 5-34
Coral, Anemones, Sea Fans, and Jellyfish
 Phylum Cnidaria includes soft and hard corals, sea anemones, hydroids,
sea fans, jelly fish, and siphonophores.
 Anatomical characteristics include:
 They are radially symmetrical – symmetry
around a central point.
 They have a cup or bag-like body made of two
layers of cells, with tentacles around the rim.
 They have a mouth that opens into the gastrovascular cavity (a space in the middle of their
body used for digestion/reproduction).
 They are structurally uncomplicated, with
simple nerves,muscle nets, and light receptors.
 Colonial organisms are called polyps.
 Individuals are free-floating and are called medusae.
 All share the ability to defend themselves with nematocysts.
 These stinging structures are composed of special cells called cnidocytes.
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Special Attributes of Coral and Anemones
 The largest class in phylum Cnidaria is class Anthozoa, the coral
and anemones.
 Hard coral are the most ecologically significant thanks
to the massive calcium carbonate reefs they build.
Chapter 5 Pages 5-34 to 5-36
Coral, Anemones, Sea Fans, and Jellyfish
 Members of this class are polyps that attach to the reef or other substrate.
 Coral and soft coral are colonial, anemones are individual organisms.
 They are sensitive to runoffs, fertilizers, etc. that
can cause damage.
 When coral are stressed they become colorless.
This is called coral bleaching – a sign of a diseased
and dying colony.
 Soft coral and sea fans grow into tree-like structures
built on protein skeletons. They are not reef builders.
 Anemones have a mutualistic relationship with
various species of anemonefish.
 The fish receive protection by living in the anemone
and the anemone receives food from the fish.
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Special Attributes of Fire Coral
and Siphonophores
 Both fire coral and siphonophores belong in the class Hydrozoa.
 Fire coral is one of the cnidarians that can sting humans.
 Siphonophores exist as planktonic colonies, yet within the colonies are special
organisms adapted to feeding, reproduction, movement and other functions.
 The Portuguese man-of-war is an example of this.
 Siphonophores can exceed 40 meters
(131 feet) in length.
Chapter 5 Pages 5-36 & 5-37
Coral, Anemones, Sea Fans, and Jellyfish
 It gets its name from the mild burn you get from touching them.
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Special Attributes of Jellyfish
 The Portuguese man-of-war is in class Hydrozoa.
 Jellyfish are members of
class Scyphozoa.
 Box jellyfish are members of
class Cubozoa.
 Comb jellyfish appear to be
jellyfish, but are members of
phylum Ctenophora.
Chapter 5 Pages 5-38 to 5-40
Coral, Anemones, Sea Fans, and Jellyfish
 It is not a jellyfish.
Jellyfish
 Comb jellies lack the bag-like
cnidarian body shape.
 Unlike jellies they have
cilia on their surfaces to
help them move.
 They lack stinging
cnidocytes.
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Characteristics of Simple Worms
 Phylum Platyhelminthes is made up of flat worms.
 They have a flattened tube of muscle, simple digestive system,
a single opening that serves as both mouth and anus.
 Phylum Nemertea are more complex with a flat shape.
 They have a simple blood vascular system, one-way digestive
system, separate mouth, and anus.
 They are carnivores.
Chapter 5 Pages 5-41 & 5-42
Simple Marine Worms
 Phylum Nematoda are structurally simple round worms.
 More complex than the other two phyla. Most are parasitic
worms, some live in sea animals.
 This phylum also includes human parasite forms.
Special Attributes of Simple Worms
 Lineus longissimus, a nemertean, found in the
North Sea is perhaps the longest known creature in the
world – more than 60 meters (197 feet).
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Characteristics of Mollusks
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1. A muscular bag called the mantle.
2. A muscular foot beneath the head.
3. The radula – a tongue with rough
scraping teeth used for feeding.
Special Attributes of Class Gastropoda
Chapter 5 Pages 5-43 & 5-44
Mollusks – A Bag, a Scraper, and a Foot
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Phylum Mollusca – the mollusks – ranges
from squid and octopuses to sea slugs,
snails, oysters, clams, and conches.
Three characteristics all members share:
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Snails, whelks, slugs, and most single-shelled mollusks belong in class Gastropoda.
Torsion is a developmental process.
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It occurs after the veliger settles and begins maturing.
Its body twists into a permanent loop that
rearranges the organs and brings them
together allowing the body to draw into the
spiral shell common to this class.
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Special Attributes of Class Bivalvia
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Belonging to class Bivalvia (bi meaning two) are mollusks that have two
hinged shells.
Mussels, clams, oysters, and scallops are all bivalves.
Special Attributes of Class Cephalopoda
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This class includes cuttlefish, squid and octopuses.
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Chapter 5 Pages 5-45 to 5-48
Mollusks – A Bag, a Scraper, and a Foot
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Cuttlefish (order Sepioidea) differ from squid and
octopuses by having an internal shell used primarily for buoyancy.
Squid (order Teuthoidea) differ from cuttlefish and
octopuses with their streamlined, torpedo-shaped
bodies adapted to life in open water.
Octopuses (order Octopoda)
differ from squid and cuttlefish
by having no shell and living in
rocky reefs and coral.
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Octopuses are probably the
most intelligent invertebrates.
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Characteristics of Annelids
 Worms in phylum Annelida stand apart
because of their structural complexity.
 They have a heart, nephridia, and sometimes, jaws.
 Most important, they exhibit metamerism
– the division of the body into repeating blocks or segments.
Special Attributes of Annelids
Chapter 5 Pages 5-49 & 5-50
Complex Worms
 Of particular relevance to oceanography – class
Polychaeta, because many polychaete worms live
in the marine environment.
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1. Tubeworms have flower-like “antennae.”
2. Bristleworms sting when touched.
3. Spongeworms live on sponges.
4. Fireworms live on the surface of fire coral.
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Characteristics of Crustaceans
 Phylum Arthropoda is the most numerous of multicellular animal phyla.
 Superclass Crustacea – an intermediate classification.
 Characteristics include:
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A pair of appendages on each body segment.
Two pairs of antennae.
Mandibles for chewing.
Teardrop-shaped larvae.
Exoskeletons are shed
as they grow.
Chapter 5 Page 5-51
Crustaceans – Underwater Arthropods
 There are several intermediate classifications.
 There may be as many as one million arthropod species.
 Characteristics: segmented bodies, jointed legs, a chitinous exoskeleton.
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Special Attributes of Class Cirripedia
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Barnacles unique lifestyle sets them apart into
class Cirripedia.
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Special Attributes of Copepods
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Copepods play a central role in the ocean food webs.
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Chapter 5 Pages 5-51 to 5-53
Crustaceans – Underwater Arthropods
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Life begins as free-swimming larvae like other crustaceans.
When the larva finds a surface on which to live (rocks, boats,
etc.) it fuses itself in place “upside down.”
The exoskeleton forms the carapace (hard shell) the barnacle
can withdraw into for protection.
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They are important primary and secondary consumers of
phytoplankton and zooplankton.
Relatively few larger animals can consume the tiniest plankton,
but many can eat the larger copepods. Fish, krill, and giant plankton
feeders, including whale sharks, baleen whales, and
manta rays all eat copepods.
Copepods are important to ocean food webs because they link the
tiny primary producers and consumers to the large animals
higher up the web.
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Special Attributes of Decapods and Krill
 Have 10 functional legs (deca meaning ten and
poda meaning foot).
 Have claws and an extended carapace that
encloses the gills.
 Because humans eat these shellfish, they are
an important food source and resource on
which the fishing industry relies.
 Order Euphausiacea: krill
Chapter 5 Pages 5-53 to 5-55
Crustaceans – Underwater Arthropods
 Class Malacostraca includes two orders of interest due to their roles as
food for humans and food for nature.
 Order Decapoda: lobsters, shrimps, and crabs
 Krill are important primary and secondary consumers
that link smaller plankton to larger consumers.
 In subpolar food webs, they are vital. Whales, seals,
sea birds, and penguins only survive in highly
productive waters. Much of the food web above krill
depends on it for life.
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Characteristics of Echinoderms
 Even though the organisms in phylum Echinodermata don’t at first
look and act much like animals, they are.
 They move. They attack prey. They defend themselves.
They just tend to do so very slowly.
 A radially symmetrical body divided into five parts.
 Most have hundreds of tiny tube feet to crawl and climb.
 Most have a water vascular system that
brings oxygen to the body cells.
Chapter 5 Pages 5-57 & 5-58
Echinoderms – Stars of the Sea
 They all share:
 Echinoderms have some traits close
to chordates.
 The adult is radially symmetrical.
 The larvae are bilaterally symmetrical.
Bilateral symmetry, along a vertical axis,
is what mammals, fish, etc. have.
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Special Attributes of Crinoids
 Long feather-like arms and short,
hook-like legs called cirri.
 They have upward-facing mouths.
 Most are nocturnal feeders. At night, they unfurl
their arms to capture plankton and nutrients carried
into their paths by the current.
 By day they coil up tightly and hide in the reef.
 Most crinoids attach to the bottom by their cirri.
Chapter 5 Page 5-58
Echinoderms – Stars of the Sea
 Class Crinoidea include feather stars and sea lilies.
 The primary characteristics of this class are:
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Special Attributes of Sea Stars
 Sea stars belong to class Asteroidea.
They are predators with downward-facing mouths.
They have tube feet covering their undersides.
They usually have five arms.
A few species have toxic spines for protection.
Each arm carries an equal share of the
animal’s systems and organs.
 They can regenerate a lost limb, some grow
into several new animals when cut into pieces.
Special Attributes of Brittle Stars
 Brittle stars belong to class Ophiuroidea.
Chapter 5 Page 5-59
Echinoderms – Stars of the Sea
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 This class has slender legs that are proportionately
longer and thinner than those on sea stars.
 Brittle stars feed on detritus and small animals.
 They use arms and tube feet for locomotion.
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Special Attributes of Sand Dollars and Sea Urchins
 Sand dollars and sea urchins are part of class Echinoidea.
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They have the five-section body, but no arms.
Sand dollars and sea urchins share a disk-shaped body.
They have tube feet on the underside.
Sea urchins graze on algae.
Swimmers avoid sea urchins because of their spines.
Special Attributes of Sea Cucumbers
 Sea cucumbers are part of class Holothuroidea.
Chapter 5 Pages 5-60 & 5-61
Echinoderms – Stars of the Sea
 Some species have toxins in the spines for self-defense.
 Urchins can move their spines to assist in locomotion.
 They have an elongated five-segment body
with tentacles around the mouth.
 Most feed by moving with their mouths open, allowing sand
to flow through. A few are filter feeders.
 Some expel a sticky mass of white tubes covered in toxin.
 They are protected by tough skins and by the ability to expel
part of their internal organs for predators while saving the rest to survive.
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Characteristics of Chordates
 Phylum Chordata are characterized by having a notochord
and a dorsal nerve cord at some point in their life cycle.
 A notochord is a firm tissue mass along the dorsal side.
 A dorsal nerve cord is a tube of nervous tissue just above
the notochord.
Special Attributes of Subphyla Urochordata
and Cephalochordata
Chapter 5 Pages 5-62 & 5-63
Invertebrate Chordates
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Subphylum Urochordata includes tunicates, colonial
drifting salps, and larvacean.
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Tunicates pump water to filter feed.
Salps are gelatinous free-floating organisms.
Larvaceans are tadpole-like planktonic organisms thought to
resemble the theorized ancestor of vertebrates.
Subphylum Cephalochordata includes 25 species of lancelet.
These small filter feeders of genus Amphioxus are significant
because they resemble vertebrates, except they lack vertebrae.
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Characteristics of Subphylum Vertebrata
 A notochord that has developed into a spinal cord protected by
vertebrae and a head with a brain characterize organisms in
this subphylum.
Significance of Class Agnatha
 This is the class of the jawless fish.
 Species include lampreys and hagfish.
 Organisms in this class are significant because they may
represent the ancestor of bony fish/sharks.
Chapter 5 Pages 5-64 & 5-65
Vertebrates – Top of the Food Web
 Vertebrates consist of the most complex, large, fast, and conspicuous organisms. They
include us, the organism that has had the most effect on the global biosphere.
 Scientists theorize that during the Cambrian period the first
of three gill arches on a jawless fish evolved into the first jaws.
 Having jaws allowed vertebrates to become very successful predators.
 Having jaws put organisms in class Chondrichthyes (sharks and rays) and class
Osteichthyes (bony fish) near the top of marine food webs.
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Characteristics of Sharks and Rays
 Class Chondrichthyes includes sharks, rays and their close relatives.
Special Attributes of Sharks and Rays
 Sharks and rays are successful predators:
 Subclass Elasmobranchii have cartilaginous skeletons.
Chapter 5 Pages 5-65 to 5-67
Sharks and Rays – Teeth and Wings
 Sharks and rays don’t look similar on the outside, but
share a basic anatomy that classifies them together.
 Sharks and rays are jawed fish, that lack a swim
bladder, and have cartilaginous skeletons.
 This characteristic saves energy. Saving energy is one of the
things that have made them successful predators.
 Sharks have a sense of smell that detect incredibly
diluted substances.
 Sharks have a “conveyor belt” of multiple rows of teeth.
 They swing into place as old teeth wear out and fall away.
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Special Attributes of Sharks and Rays (continued)
 Both have lateral lines – lines of sensory hair along the length of the body
that detect water motion and vibrations.
 Unique to elasmobranchs is electroreception – the ability to sense minute electricity
created by muscles and nerves.
 Sharks and rays have organs called ampullae of Lorenzini which you can see as
visible pits near their snouts used to detect the electrical current.
Chapter 5 Page 5-69
Sharks and Rays – Teeth and Wings
 Sharks and rays have other interesting characteristics:
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Special Attributes of Sharks and Rays (continued)

Elasmobranchs differ in their reproductive strategy.
 The male deposits sperm in the female via a pair of copulatory organs called claspers found at
the base of the pelvic fins.
 The female lays an egg case in which the juveniles develop for up to six months at which time
one or more sharks or rays emerge.
 A few shark species are ovoviviparous – the eggs hatch within the mother’s body.
 They give birth to live young rather than egg cases.
 The largest fish in the ocean.
 Shark size ranges from hand-sized to the
whale shark – the largest fish in the ocean.
Chapter 5 Page 5-69
Sharks and Rays – Teeth and Wings
 Sharks and rays produce fewer, but more mature offspring.
 Most fertilize their eggs internally.
 Whale sharks can reach 14 meters (46 feet).
 Basking sharks can reach 10 meters (33 feet).
 Megamouth sharks can reach 6 meters (20 feet).
 All three are filter feeders that consume plankton.
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Special Attributes of Rays
Chapter 5 Page 5-71
Sharks and Rays – Teeth and Wings
 Superorder Batidoidimorpha of subclass Elasmobranchii consists of the
rays, which includes skates and guitarfish.
 Ray anatomy is well suited to life on sandy
bottoms or midwater.
 Specially adapted to life in midwater are
the eagle ray and manta ray.
 Pectoral fins have become “wings” that
stretch forward over the gills and are fused
to the sides of the head.
 Shoulder girdles are flattened and many
bones are fused together for rigidity.
 No longer need a tail for swimming, the tail
has become a defensive whip in some species.
 Rays literally fly through the water.
 The largest rays are mantas with wingspans
exceeding 8 meters (26 feet).
 Like the largest shark, the mantas feed on plankton.
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Characteristics of Bony Fish
 Class Osteichthyes are jawed fish with bone skeletons.
 They control the swim bladders with oxygen gas exchanged to and from blood circulation.
 Many have a special organ called the gas gland and the rete mirabile that take up gases from
the bloodstream for the swim bladder.
 This allows many species to hover nearly motionless in midwater.
 Most bony fish reproduce externally.
 The female lays her eggs, the male
immediately fertilizes them.
 Their strategy is to produce a vast number
of off-spring with only a few expected
to survive to maturity.
Chapter 5 Page 5-73
Bony Fish – Half the World’s Vertebrates
 Most have a swim bladder and scales.
 Most control buoyancy by adding or releasing gas to/from their swim bladder.
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Characteristics of Bony Fish (continued)
 Bony fish have lateral lines that detect water
motion and vibrations.
 Most open ocean and schooling fish have a torpedo-like
streamlined shape that minimizes drag and turbulence.
 This fusiform shape is spindle-like, slightly broader at the
head and a V-shaped tail. This makes them fast swimmers.
Chapter 5 Pages 5-74 & 5-75
Bony Fish – Half the World’s Vertebrates
 Bony fish have characteristics for life on the reef and for life in the
open ocean:
 Most open-ocean and schooling fish have a lighter underside and dark topside
for concealment.
 Bony fish living in reefs and on the bottom use
survival strategies more diverse and include
concealment and armor instead of swimming.
 For this reason, you see far more diversity in color,
shape, and size among reef and bottom fish.
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Special Attributes of Orders
Clupeiformes and Gadiformes
 Two orders in class Osteichthyes have an important
place in worldwide fisheries.
 About one-quarter of all fish caught come from this order.
 2. Order Gadiformes which includes cod, pollack,
haddock, whitings, and their relatives.
 This order continues to produce about a sixth of the
world’s fish catch.
Chapter 5 Pages 5-75 & 5-76
Bony Fish – Half the World’s Vertebrates
 1. Order Clupeiformes which includes herrings,
pilchards, sardines, and anchovies.
 Alaskan pollack, the haddock and whitings have
become important fisheries.
 Historically, worldwide fisheries have influenced
politics and caused wars.
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Characteristics of Reptiles
Organisms in class Reptilia mostly live on land or in freshwater. Relatively
few live in the ocean. They have these characteristics in common:

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Are generally cold-blooded and have scales.
Reproduce (most species) by laying internally fertilized eggs.
Breathe with lungs at all stages of their lives.
Special Attributes of Marine Crocodiles,
Turtles, Snakes, and Lizards

Three orders of reptiles having marine species are:
 Order Crocodilia – alligators, crocodiles, and caimans.
 Members of this order are semi-aquatic with most living in
freshwater. Exception is the giant saltwater crocodile.
Chapter 5 Pages 5-77 to 5-80
Marine Reptiles – Cold Blood and Warm Water

 Order Chelonia – turtles and tortoises.
 There are seven species of marine turtles – all live in
warm waters.
 Order Squamata – snakes and lizards.
 61 species of sea snake are true marine organisms.
Only one lizard is a true marine reptile – the marine iguana.
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Characteristics of Birds

Birds are vertebrates in class Aves. They share several characteristics:

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
Feathers, unique to this class.
Forelimbs that are wings.
A four-chambered heart and lay internally fertilized eggs.
Marine birds are important to the marine ecosystem:

Chapter 5 Page 5-81
Seabirds – At Flight Over and In the Ocean
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They are predators that consume
fish, crustaceans, and mollusks.
In turn they are prey to marine mammals and sharks.
They supply guano – a significant source
of nutrients, specially organic nitrogen important to sea life.
Many species of birds exhibit related adaptations to an aquatic life:


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Webbed feet for swimming and floating on the surface.
Bill adaptations suited to their marine prey, like the pelican’s pouch.
The cormorant flies over water, and dives in it in pursuit of prey.
Birds, like the albatross, have wings and flight characteristics adapted to long-duration flying over
wide expanses of water.
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 Penguins, order Sphenisciformes, all live in the Southern hemisphere.
 Penguins make up about 80% of all
Antarctic birds and by far
outnumber even the massive
marine mammal populations.
 Not all species live in cold places.
 Penguins are found on the coasts of
South America, Africa, Australia,
New Zealand, and the nutrient-rich waters
surrounding the Galapagos Islands
near the equator,
Chapter 5 Page 5-82
Seabirds – At Flight Over and In the Ocean
Special Attributes of Penguins
 They cannot fly, but they’re as at home
underwater as other birds are in the air.
 They dive hundreds of times daily hunting for food.
 They can reach depths of 100 meters (328 feet) and deeper.
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Characteristics of Marine Mammals
 They have hair on some part of the body.
 They nourish their young with milk provided by mammary glands.
 Mammals are homeothermic (warm-blooded) with a
constant internal temperature.
 The majority give birth to live young.
 The marine environment poses several challenges
to mammalian physiology:
 1. Compared to living in air, life in water demands high
oxygen consumption.
Chapter 5 Pages 5-83 & 5-84
Marine Mammals – Warm Blood in Cold Water
 All organisms in class Mammalia share these characteristics:
 Marine mammals meet this challenge by breathing air.
 2. There is a need to dive holding their breath for
long periods.
 They use myoglobin, a protein, to bind reversibly with oxygen to make it available for use
in metabolism.
 They use the mammalian diving reflex – is when diving pulse rate slows and blood flow
diverts from the muscles to the heart and brain.
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Characteristics of Marine Mammals (continued)
 Marine mammals’ lungs and sinuses are very flexible, allowing compression
without pain or injury.
 Some dolphins and whales have lungs that engorge with blood thus offsetting
the compressed space.
 4. The challenge of easy movement through the dense medium of water.
 The use of streamlining and hydrodynamics helps with this.
 5. The challenge of the senses. They need to hear, see, and smell underwater.
 Dolphins and whales use echolocation (natural sonar) to determine distance,
size, density, and shape.
 Seals and sea lions have sensitive hearing and excellent underwater eyesight.
They see poorly above water, but have a keen sense of smell.
Chapter 5 Pages 5-84 to 5-86
Marine Mammals – Warm Blood in Cold Water
 3. The water pressure and a need to equalize.
Special Attributes of Seals and Sea Lions

The seals and sea lions belong in order Pinnipedia.

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Seals: don’t have ear flaps, rear flippers point backward and cannot
rotate forward, out of water seals crawl on their stomachs.
Sea Lions: have ear flaps, hind flippers rotate, can sit upright and run.
Walrus: don’t have ear flaps, hind flippers rotate, can sit upright.
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Special Attributes of Dolphins, Whales
and Porpoises
 Suborder Mysticeti: a group of filter feeders made up of baleen whales.
 Suborder Odontoceti: a group of toothed whales made up of sperm whales, dolphins
and porpoises. They are predators.
 Family Delphinidae: are the dolphins and orcas, one of the most varied and successful groups
among the toothed whales.
 Most cetacea use echolocation and communicate by sound.
Chapter 5 Pages 5-86 & 5-87
Marine Mammals – Warm Blood in Cold Water
 Whales, porpoises, and dolphins come from different families organized
under the order Cetacea. Cetaceans are divided into two suborders:
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Special Attributes of Dugongs and Manatees
Dugongs and manatees (sometimes called sea cows)
belong to order Sirenia, which has four species.
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All four are the only herbivorous marine mammals.
Manatees are known for migrating to and from fresh- and
saltwater environments.
Marine Mammals and Human Interaction

Human activities have endangered marine mammals and continue to do so.

Whaling brought whales to the verge of extinction.

Chapter 5 Pages 5-88 & 5-89
Marine Mammals – Warm Blood in Cold Water

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Banned or greatly limited by international convention
today, some species seem on the rise, others do not
seem to be recovering.
People have hunted seals for their fur and manatees for meat.
Dolphins have been killed as bycatch in tuna fishing.
Pollution and overfishing raise new threats.

Because of their high metabolisms and energy demands,
marine mammals require highly productive environments
to survive.
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