Transcript Introduction to Animal Diversity

Introduction to Animal
Diversity
Chapter 32
What is an animal?
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Eukaryote?
Multicellular?
Large and furry?
Cambrian explosion
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542-251 MYA
Few phyla before
About ½ of all extant (existing) phyla
developed in this time period
Why?
Animals
• Multicellular
– No cell wall
– Cells held together by structural proteins (eg.
collagen)
Cells of plants and fungi
have rigid cell walls
(cellulose or chitin)
Animals
• Multicellular
– No cell wall
– Cells held together by structural proteins (eg.
collagen)
• Heterotrophic
• Have unique tissues
– Muscle
– Nervous
Reproduction and Development
• Most animals reproduce sexually
– Small sperm fertilizes a large egg
– Forms a zygote
• Zygote undergoes mitotic cell divisions
(cleavage)
• Forms hollow blastula
• Folds to form a gastrula
– Folds form tissues
Embryonic tissue – embryonic stem cells – pluripotent stem cells
Reproduction and Development
• Maturation processes
– Embryo → Adult
– Embryo → Larva → Adult
– Larvae undergo metamorphosis to mature to
adult
Homeotic (Hox) genes
• Hox genes regulate the expression of other
genes during development
• Therefore Hox genes regulate body patterning in
animals
• Many Hox genes contain homeoboxes
– 180 bp DNA sequence common to almost all animals
as well as plants and prokaryotes
Animal Body Plans
• Symmetry
– Radial, with a central axis
– Bilateral, left/right symmetry
• Often with “cephalization”
Dorsal side
Posterior
Anterior
Ventral side
Animal Body Plans
• Symmetry
• Tissue Types
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Form from germ layers
Ectoderm forms outer layers (skin)
Endoderm - inner layers (gut)
Mesoderm – middle layers (muscle)
• Body cavity
– Called the coelom
– Animals can be acoelamate, pseudocoelomate, or
coelomate
Protostomes vs Deuterostomes
• Cleavage
• Coelom formation
• Blastopore
Cell retains flexible
potential, one may grow
into intact embryo
Human cloning report sparks calls for ban
Lawmakers, church leaders aghast over 'unethical science'
The Associated Press
Updated: 9:33 p.m. ET Feb. 12, 2004
SEATTLE - In a clash of politics and science,
the first successful cloning of a human
embryo — and the extraction of stem cells
from it — has ignited new calls for a ban on
all forms of human cloning in the United
States.
Coelom Formation
Fate of Blastopore
• Protostome = first mouth (blastopore
forms mouth)
–Mollusca, Annelida, Arthropoda
• Deuterostome = second mouth (mouth
forms from an opening other than
blastopore); anus forms from or near
blastopore
–Echinodermata and Chordata
Animal Diversity
• Definition of an animal
– Multicellular
– Heterotrophic
– Having unique tissues (nervous, muscle)
– Reproduction
– Development
Animal Diversity
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What are major groupings of animals?
How are they related to each other?
What features do they share (similarity)?
What features differ (dissimilarity)?
What are major themes of variation?