Download Biology 1030 Winter 2009 1

Biology 1030
Winter 2009
Animal Diversity
Chapters 32, 33 and 34 (select pages)
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Living Organisms
• Three Domains of life
– Bacteria
– Archaea
– Eukarya
• True nucleus
• True organelles
• Heterotrophic
– Animals
– Fungi
– Protists
• Autotrophic
– Plants
– Protists
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Heterotrophic Protists
• Paraphyletic grouping
– Lack chloroplasts
• Protozoans
– Unicellular
• Animal-like
Animal like protists
– Diplomonads (Giardia)
– Ciliates (Paramecium)
– Unikonta
• Amoebozoans
– (Amoeba)
• Opisthokonta
– (Choanoflagelates)
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Biology 1030
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Choanoflagelates
• Predecessor of all
animals
• Colonial protists
• Collared cells
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What is an Animal?
•
Animals are characterized by multiple traits:
–
Multicellular
• Cells interconnected through various junctions
–
Lack cell walls
–
Heterotrophic
–
Directional motion
–
Diplontic life cycle
–
Tissues develop from
germ layers
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Animal Diversity
•
Over 1.5 million
described species of
animals
– Insects
– Underestimate
•
Two large, general
groups of animals:
1. Invertebrates
2. Vertebrates
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Biology 1030
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Phyla
• A large taxonomic grouping of related
animals
• 30-35 total phyla
• 10 ‘major’ phyla
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Phyla You Need to Know
• Porifera
• Cnidaria
• Echinodermata
• Chordata
• Nematoda
• Arthropoda
• Platyhelminthes
• Brachiopoda
• Annelida
• Mollusca
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Animal Classification
•
To classify animals, we ask the following questions:
1. Are there true tissues?
2. If yes, how many layers?
3. What is the pattern of development?
4. How do they grow?
4b. Special structure?
5. Is there body symmetry?
6. Is there a body cavity?
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Biology 1030
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1. Are Tissues Present?
• What is a tissue?
– A group of cells
– If one or a few cells are removed:
• They cannot perform their task
• They will eventually die
• Two major groups
– Parazoa
• Phylum Porifera
– Eumetazoa
• Everything else
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Ph. Porifera
• The Sponges
• The first animals
– Colonial protists
(Choanoflagellates)
• All are aquatic and
benthic
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Poriferan Body Plan
• Sponges have no true
tissues
– Three layers of cells only
• Pinacoderm
– Pinacocytes
– Porocytes
P
t
• Mesohyl
– ‘Spongocytes’
• Choanoderm
– Choanocytes
• But…
– Why not true tissues?
– Totipotency
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Biology 1030
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Poriferan Body Plan
• Each cell is totipotent
– Not dependent on each other
– Able to change
– Useful for asexual reproduction
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2. How Many Tissue Layers?
• Animals with true tissues
• Invagination of a hollow
ball of cells
– Ectoderm outside
– Endoderm inside
= Diploblastic
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How Many Tissue Layers?
• In most animals
– Ectoderm
– Endoderm
– Mesoderm forms between
• Two major groups:
– Diploblastic
– Triploblastic
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Biology 1030
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Phylum Cnidaria
• Jelly fish, anemones,
corals
• Diploblastic
– Ectoderm (epidermis)
– Endoderm (gastrodermis)
– Space between is filled
with mesoglea
• 2 basic body shapes
– Medusa
– Polyp
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Cnidocytes
• Nematocysts
• Specialized stinging
cell
– Highly venomous
– Paralyzes prey
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Cnidarian Body Plan
• Colonial cnidarians
– All individuals are clones
• Corals
– Autozooids are similar in
p
gy
morphology
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Biology 1030
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Cnidarian Body Plan
• Specialized colony
members
– Dactylozooid
– Gastrozooid
– Gonozooid
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3. What Type of Development?
• Animal development
• Diplontic life cycle
• The zygote
– Undergoes cleavage
• The morula
– A solid ball of cells
• The blastula
– A hollow ball of cells
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Gastrulation
• Arranges the tissue layers correctly
• Forms the primitive digestive tract or
archenteron
• Creates an opening (blastopore)
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Biology 1030
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3. What Type of Development?
• Fates of the blastopore:
1. Formation of the mouth
• Protostome development
(mouth first)
2. Formation of the anus
• Mouth forms later
• Deuterostome
development (mouth
second)
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The Deuterostomes
• Radial cleavage
• Indeterminate development
• Enterocoelous
– Outpockets from archenteron
• Echinodermata
• Chordata
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The Protostomes
• Spiral cleavage
• Determinate development
• Schizocoelous
– Splitting of solid masses of mesoderm
• The remaining phyla
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Biology 1030
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Phylum Echinodermata
• Divided into 5 major classes
–
–
–
–
–
Class Crinoidea
Class Asteroidea
Class Ophiroidea
Class Echinoidea
Class Holothuroidea
• All species are marine
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Echinoderm Body Plan
• Larvae have bilateral
symmetry
• Pentaradial (secondary)
symmetry as adults
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Echinoderm Body Plan
• The water vascular system
–
–
–
–
Locomotion
Gas exchange
Circulation
Prey capture
• An adaptation of their coeloms!
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Biology 1030
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Echinoderm Body Plan
• All have a calcareous endoskeleton of several
plates or ossicles
– Microscopic remnants
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Echinoderm Regeneration
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Phylum Chordata
• Characteristics
– Dorsal hollow nerve cord
– Notochord
– Post-anal tail
– Pharayngeal gill arches
/slits
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Phylum Chordata
• Three major subphyla
– Subphylum Cephalochordata
– Subphylum Urochordata
– Subphylum Vertebrata
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Pharyngeal Gill Arches
• Highly modified in the
more derived
chordates
– Ancestral uses
– Form the jaws
j
((arch 1))
– Form the inner ear
(arches 1 & 2)
– Form the cartilages of
the throat (arches 4 & 5)
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Subphylum Cephalochordata
•
•
•
•
The lancelets
Small, fish-like animals
Only 25 species
Filter-feeders, catching
food in their 100+ gill
arches
• Believed to be the earliest
chordates
– Fossils found in the
Burgess Shale and
Chengjiang deposits
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Biology 1030
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Subphylum Urochordata
• The tunicates
• Defining characteristics only in the
larval stages of development
• Most are filter-feeders, but one is an
active predator
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Subphylum Vertebrata
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Recall the Protostomes
• Spiral cleavage
• Determinate development
• Schizocoelous
– Splitting of solid masses of mesoderm
• The remaining phyla
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4. What Type of Growth Pattern?
• Two different methods of growth
– Growth by continually extending their skeletons
– Growth by moulting body coverings
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The Lophotrochozoans
• Growth by extension of
their skeletons
• A common larval form
– Trochophore larva
– Annelids & Mollusks
• A feeding structure
– Lophophore
– Brachiopods
• Neither
– Platyhelminths
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The Ecdysozoans
• These animals are covered
by a hard covering
• Growth occurs by moulting
or shedding their cuticle or
exoskeleton
– Ecdysis
• Nematodes
& Arthropods
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Biology 1030
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Phylum Nematoda
• The round worms
• The most abundant group of the Eumetazoa
– Found in all habitats
– Free-living and parasitic forms
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Nematode Body Plan
• Free-living species are
generally small, interstitial
worms
– µm – mm scale
• Parasitic species can be
very large
– cm – m scale!
• Dracunculus can grow
over 1m!
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Nematode Body Plan
• Body covering is a cuticle
– A clear, tough but flexible, non-living covering
– Not an exoskeleton
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Biology 1030
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Free-Living Nematodes
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Parasitic Nematodes
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Phylum Arthropoda
• Well over 1,000,000 species described!
• All arthropods are characterized by:
• Exoskeleton with jointed appendages
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Arthropod Body Plan
• Segmentation is obvious
– Generally each segment has a pair of appendages
– Similar segments are
grouped into body
regaions or tagmata
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Phylum Arthropoda
• Divided into multiple Subphyla including:
–
–
–
–
Subphylum
Subphylum
Subphylum
Subphylum
p y
Myriapoda
Cheliceriformes
Hexapoda
Crustacea
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Myriapod Body Plan
• Centipedes and millipedes
• Homonomous
segmentation
– Except for the head region
• Legs are simple unbranched
– The major difference is the number of legs per
segment
~30 segments × 2 legs/segment =
~190 segments × 4 legs/segment =
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Biology 1030
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Cheliceriform Body Plan
• The spiders, mites, scorpions and ticks
• Segments are grouped into 2 tagmata
– Anterior cephalothorax
– Posterior abdomen
• The chelicerae (chelicera sing.)
• 4 pairs of unbranched
walking legs
• No antennae
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Hexapod Body Plan
• Over 1,000,000 described species!
– Dominate terrestrial environments
• Light-weight chitinous exoskeleton
• Three tagmata
– Head – 5 segments
– Thorax – 3 segments
• Legs and wings
– Abdomen – up to 11
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Crustacean Body Plan
• The crabs, lobsters, shrimp, barnacles, copepods
– Mostly aquatic with a few terrestrial species
• Heavy calcarious carapace
• Body divided into 2 tagmata
– Cephalothorax
• Biramous appendages
• Several pairs of antennae
– Abdomen – or tail
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The Lophotrochozoans
• Growth by extension of
their skeletons
• A common larval form
– Trochophore larva
– Annelids & Mollusks
• A feeding structure
– Lophophore
– Brachiopods
• Neither
– Platyhelminths
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Phylum Platyhelminthes
• The flat worms
• Possess neither a trochophore
larvae or a lophophore
• 3 major classes
– Class Turbellaria
– Class Cestoda
– Class Trematoda
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Platyhelminth Body Plan
• They have a solid body construction
– Acoelomate
• All flat worms exhibit bilateral symmetry
– Rudimentary
R di
t
light-sensitive
li ht
iti eye-spots
t
• Flat worms have an incomplete, two-way gut
– The gastrovascular cavity
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Biology 1030
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Phylum Platyhelminthes
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Phylum Brachiopoda
• The lamp shells
• One of a few lophophorate phyla
• Not clams!
– Different plane of symmetry
– Different mode of life
– Different musculature
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Brachiopod Body Plan
• Most are sessile - pedicle
– Some dig through the sand
• Valves are produced by a
mantle as in the molluscs
– P
Predominant
d
i
t iin th
the ffossil
il
record
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Biology 1030
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Protostome Development?
• Cleavage is radial
• The second opening becomes the mouth
– The blastopore disappears
• The third opening becomes the anus (if it forms)
– The Inarticulata have a complete, 1-way gut
– The
e Articulata
t cu ata have
a e an
a incomplete,
co p ete, 2-way
ay gut
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Phylum Annelida
• The segmented worms
• Three major classes
– Class Polychaeta
– Class Oligocaeta
– Class Hirudinea
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Annelid Body Plan
• Obvious segmentation
– In many, the segments are all similar –
homonomous
– Others have segments that are specialized –
heteronomous
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Annelid Body Plan
• Trochophore larval
• Paired setae (chaetae) on nearly all segments
– Polychaetae –
– Oigochaetae –
– Hirudinea –
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Polychaete Body Plan
• Predominantly marine worms with
parapodia on each segment
– Multitasking
• Well-developed head with palps
– Multitasking
g
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Oligochaete Body Plan
• Mainly terrestrial (some freshwater) worms
– No parapodia, & small setae or bristles
• Streamline body shape
– Reduced head
• No palps
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Biology 1030
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Hirudinean Body Plan
• Body is dorsoventrally flattened
– Anterior and posterior suckers
• Segmentation is reduced to accommodate
large blood meals
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Phylum Mollusca
• All with a trochophore larval stage
• Can be found in all environments marine, freshwater
and terrestrial (moist habitats)
• Four major classes
–
–
–
–
Class Polyplacophora
Class Gastropoda
p
Class Bivalvia
Class Cephalopoda
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Molluscan Body Plan
• Despite this variety all mollusks are
variations on a common theme
1. Muscular foot
2. Mantle
3. Radula
4. Visceral mass
• A great example of
adaptive radiation
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Class Polyplacophora
•
•
•
•
The chitons
Muscular foot for crawling
Flexible 8-piece shell
Tongue-like radula
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Class Gastropoda
• The snails and slugs
• Crawling muscular foot
• Single spiral shell
– slugs
• Tongue-like
T
lik radula
d l
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Class Bivalvia
•
•
•
•
The clams, scallops, mussels etc.
Digging foot in some
Shell in 2 hinged pieces
No radula
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Class Cephalopoda
•
•
•
•
The squid & octopi
Foot modified into tentacles
Shell reduced or absent
Beak-like radula
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5. Type of Body Symmetry?
• Most sponges (parazoa) are asymmetrical
– A ‘random’ growth of cells with no plane of
symmetry
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5. Type of Body Symmetry?
• The ancestral eumetazoan character trait is
radial symmetry
– Where there are several planes of symmetry
– Radial animals are divided on an oral-aboral axis
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5. Type of Body Symmetry?
• The more derived trait is bilateral symmetry
– Only a single plane creates two ‘equal’ halves
• Bilateral animals have multiple axes or ‘sides’
– Anterior – Posterior
– Dorsal – Ventral
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Cephalization
• Two major groups of animals
– Radiata
– Bilateria
• The concentration of sensory organs at the
anterior end
• Clustering of neurons
– Ganglia
– Brains
• Complex behaviours
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6. Is There a Body Cavity?
• The body cavity is called the coelom
– The fluid-filled space around internal organs
– Room for internal organs to expand and move
• Only looked at in triploblastic animals
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6. Is There a Body Cavity?
• Eucoelomate
– A cavity completely
lined with mesoderm
• Pseudocoelomate
– A cavity partially lined
with mesoderm (and
endoderm)
• Acoelomate
– No cavity
– The ‘space’ is
completely filled with
mesoderm
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Animal Phylogeny
• The traditional
phylogenetic tree –
shared characters
– Anatomical features
– Developmental characters
– Embryological characters
• New technologies –
molecular data
– DNA and rRNA sequencing
• Molecular phylogeny
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Read Concept 32.4
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