Learning Objectives The Animal Kingdom: An Introduction to Animal Diversity

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4/2/2012
Learning Objectives
The Animal Kingdom:
An Introduction to Animal
Diversity
Chapter 29
Kingdom Animalia
Animal Characteristics:
• Multicellular Eukaryotic
• Heterotrophic
• Cells specialized for specific functions
Charecteristics that most animals have
• Most are capable of locomotion at some time during life
cycle
• Most can respond to external stimuli
• Most can reproduce sexually
Animals
live inEnvironments
diverse Environments
Marine
• Provide
• relatively stable temperatures
• buoyancy
• readily available food
• Fluid and salt balance
• more easily maintained than in fresh water
• What characters are common to most animals?
• Advantages and disadvantages of different
environments
• Searching for relationships (phylogeny)
• Phylum Protista
• Phylum Cnidaria
• Phylum Ctenophora
Sexual Reproduction
• Sperm and egg unite (zygote)
• Zygote undergoes cleavage
• cell divisions produce hollow ball of cells
(blastula)
•
• Blastula undergoes gastrulation
• forms embryonic tissues
Fresh Water Environments
• Provides
• less constant environment
• less food
• Animals must osmoregulate
• fresh water is hypotonic to tissue fluid
• Disadvantages:
• currents and other water movements
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Terrestrial Environments
• Have adaptations that:
• protect them from drying out
• protect them from temperature changes
• protect their gametes and embryos
Animall Fossils
• Earliest Known animal fossils
600 mya– 540 mya
Small simple critters
Suggests sponges, jelly fish were present
• Molecular evidence indicates:
- genes that control development, rna, other molecules
similar among all animal groups
- suggests a common ancestor - monophyletic
Relationships Based on Structure
(True tissues)
• How do we determine relationships among
animal phyla?
• Genetics
• Structure
Radial and Bilateral Symmetry
2. Body Cavity
• What is it? - The space between the body wall and
the digestive tube
• “Coelom” (pronounced: see lome)
• 3 types of body cavities
- Acoelomates (no cavity)
- Psuedocoelomates (false cavity)
- Coelomates (true cavity)
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Germ layers: embryonic tissue layers
Endoderm
Ectoderm
Mesoderm
Ectoderm - epidermis and nervous tissue
Endoderm - lining of gut and some digestive
organs
Mesoderm - most body structures (bones,
muscles, circulatory system)
Triploblastic vs Diploblastic
Body Cavities in Triploblastic critters
Epidermis
(from ectoderm)
Pseudocoelom
Muscle layer
(from
mesoderm)
Epidermis
(from ectoderm)
Muscle layer
(from mesoderm)
Mesenchyme
(gelatin-like
tissue)
(a) Acoelomate—flatworm (liver fluke).
Epithelium (from
endoderm)
Epithelium
(from endoderm)
(b) Pseudocoelomate—nematode.
Fig. 29-4a, p. 624
Fig. 29-4b, p. 624
Bilateral Animals
Coelom
• Two major evolutionary branches:
Epidermis
(from ectoderm)
Muscle layer
(from mesoderm)
Peritoneum
(from mesoderm)
• Protostomia
Epithelium
(from endoderm)
Mesentery
(from mesoderm)
• Deuterostomia
(c) True coelomate—vertebrate.
Fig. 29-4c, p. 624
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Coelom Formation
Blastopore
• Opening from embryonic gut to outside
• In protostomes
• develops into the mouth
• In deuterostomes
• becomes the anus
Cleavage
Spiral and Radial Cleavage
• Protostomes
• undergo spiral cleavage
• early cell divisions diagonal to polar axis
Protostomes
• Deuterostomes
• undergo radial cleavage
• early cell divisions either parallel or at right angles
to polar axis
• cells lie directly above or below one another
Dueterostomes
Relationships Based on Structure
Cleavage
(True tissues)
• Protostomes
• undergo determinate cleavage
• fate of each embryonic cell is fixed very early
• Deuterostomes
• undergo indeterminate cleavage
• fate of each embryonic cell is more flexible
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Molecular Systematics
Take home message
• Biologists classify animals based on their body
plan and features of their early development
• Confirmed much of animal phylogeny based
on structural characters
• including axiom that animal body plans usually
evolved from simple to complex
Parazoa
Eumetazoa
Bilateria
Radiata
Acoelomates
Coelomates
Pseudocoelomates
Protostomia
Porifera
Deuterostomia
Segmentation
Segmentation
Pseudocoelom
Deuterostome
development
True coelom
Radial
symmetry
Protostome development
Three tissue layers (mesoderm)
Bilateral symmetry
Tissues (ectoderm and endoderm)
Multicellularity
Choanoflagellate
ancestor
Fig. 29-7, p. 627
Phylum Porifera
Phylum: Porifera (Sponges)
•
10,000 species, mainly marine
• Sponges
• animals characterized by
flagellate collar cells
(choanocytes)
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Sponge Structure
Porifera (Sponges) “to have pores”
• Sponge body
•
Primitive animalsLack symmetry - some radial
• No tissues
• No gut - intracellular digestion
• sac with tiny openings for water to enter
• central cavity (spongocoel)
• open end (osculum) for water to exit
•
• Sponge cells
• loosely associated
• do not form true tissues
Osculum
Porifera Life?
Water movement
Incurrent
pores
Spongocoel
•
•
•
•
Epidermal
cell
Porocyte
Spicule
Flagellum
Microvillus
Nucleus Collar cell Amoeboid cell
in mesohyl
Collar
Gas exchange?
Food?
Waste?
Sex?
- Asexual
- Sexual (most are hermaphrodites)
- amoeboid cells develop into gametes
- cross fertilize
Fig. 29-9b, p. 630
Parazoa
Radiata
•
•
•
•
•
•
Absorb food through cell
No nervous system
Skeletal system of spicules
Swimming larvae
Gas exchange by diffusion
http://www.biology.ualberta.ca/cours
es.hp/zool250/animations/Porifera.sw
f
Eumetazoa
Bilateria
Coelomates
Pseudocoelomates
Porifera
Protostomia
Deuterostomia
Cnidaria
Porifera (Sponges)
Acoelomates
Segmentation
Segmentation
Pseudocoelom
Deuterostome
development
True coelom
Radial
symmetry
Protostome development
Three tissue layers (mesoderm)
Bilateral symmetry
Tissues (ectoderm and endoderm)
Multicellularity
Choanoflagellate
ancestor
Fig. 29-7, p. 627
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Phylum: Cnidaria - ~10,000 spp.
•Jelly fish
•Anemones
•Coral
Phylum: Cnidaria
•
•
•
•
•
•
•
Body radially symmetrical
Body a hollow sac
Mouth serves to ingest food and expel
wastes
Two tissue layers - Diploblastic
- ectoderm - epidermis
- endoderm - gastrodermis (digestion)
separated by the mesoglea
Digestion is extracellular!!!
Sexual and asexual
Cnidocytes that contain Nematocysts!
- Two types of body forms
Radial Symmetry
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Nematocysts
Phylum Cnidaria
• Gastrovascular cavity
– with single opening for mouth and anus
– Forms a hydrostatic skeleton
• Nerve cells (not really) form irregular nerve nets
– sensory cells with contractile ability
Mouth
Class Hydrozoa
Epidermis
•Polyp body form
•Fresh water
•Sessile
•Asexual/Sexual
Mesoglea
Gastrodermis
Gastrovascular
cavity
Class Hydrozoa (polyp)
Mouth
Class: Schyphozoa (Jellyfish)
Fig. 29-10a, p. 633
Mesoglea
Gastrodermis
Epidermis
Gastrovascular
cavity
Sexes separate
Males release sperm
through mouth!!
Class Scyphozoa (medusa)
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http://www.youtube.com/watch?v=oHiVA9J
_YIM
Mouth
Tentacle
Medusae
. Class Cubozoa (“box jellyfish”)
Feeding
polyp
– have complex eyes that form blurred images
– 4 tentacles
– Fast! Active Hunters
Medusa bud
Reproductive
polyp
Gastrovascular
cavity
Egg
Sperm
Planula
larva
Polyp colony
Young
polyp colony
(b) Life cycle of Obelia.
Fig. 29-13b, p. 635
Mouth
Class: Anthozoa (sea anemones + coral)
Epidermis
Mesoglea
Gastrodermis
Gastrovascular
cavity
Class Anthozoa (polyp)
Fig. 29-10c, p. 633
Class: Anthozoa (sea anemones + coral)
• Individual and colonial forms
• No free swimming medusa stage
• Coral
- Colonies
- Symbiotic relationship with algae
(Zooxanthellae)
- Secrete a matrix on which calcium
carbonate is deposited
- Tremendous biodiversity
- “Bleaching” (bacteria? Temp.? Ph.)
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http://www.archipelago.co.uk/project/whatis-coral-bleaching-animation/
Do not post photos on Internet
Fig. 28.11
Parazoa
Radiata
Ctenophora
Porifera
Cnidaria
Acoelomates
Eumetazoa
Bilateria
Phylum Ctenophora (comb jellies) (100 spp.)
Coelomates
Pseudocoelomates
Protostomia
Deuterostomia
• Radial symetry, Medusa body form - NO Cnidocytes,
Cilia like combs on tenticles
Segmentation
Segmentation
•fragile, luminescent marine predators
•eight rows of cilia that resemble combs
True coelom
Radial
symmetry
•tentacles with adhesive glue cells
Protostome development
Three tissue layers (mesoderm)
Bilateral symmetry
Tissues (ectoderm and endoderm)
Multicellularity
Fig. 29-7, p. 627
Parazoa
Eumetazoa
Bilateria
Hemichordata
Chordata
Echinodermata
Mollusca
Annelida
Deuterostomia
Arthropoda
Tardigrada
Nematoda
Nemertea
Platyhelminthes
Cnidaria
Ctenophora
http://www.youtube.com/watch?v=G7WT81ukHZE
Coelomates
Acoelomates Pseudocoelomates
Protostomia
Porifera
Comb Jelly
Choanoflagellates
Radiata
Onychophora
Choanoflagellate
ancestor
Rotifera
Pseudocoelom
Deuterostome
development
Segmentation
Segmentation
Pseudocoelom
Deuterostome
development
True coelom
Radial
symmetry
Protostome development
Three tissue layers (mesoderm)
Bilateral symmetry
Tissues (ectoderm and endoderm)
Multicellularity
Choanoflagellate
ancestor
Fig. 29-7, p. 627
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Parazoa
Eumetazoa
Bilateria
Chordata
Hemichordata
Arthropoda
Onychophora
Tardigrada
Nematoda
Rotifera
Annelida
Lophophorate
phyla
Mollusca
Nemertea
Platyhelminthes
Cnidaria
Ctenophora
Ecdysozoa
Lophotrochozoa
Echinodermata
Deuterostomia
Protostomia
Porifera
Choanoflagellates
Radiata
Segmentation
Segmentation
Segmentation
Protostome
pattern of
development
Radial
symmetry
Deuterostome
pattern of development
Bilateral symmetry, three
tissue layers, body cavity
Tissues
Multicellularity
Choanoflagellate
ancestor
Fig. 29-8a, p. 629
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