Introduction to Animal Diversity

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Introduction to Animal Diversity

• Chapter 32

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Biologists have identified 1.3 million living
species of animals.

• Estimates of the total number of animal species
  run far higher.
• Estimates suggest 10 to 20 million to as many as
  100 to 200 million.

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Animal Characteristics

• Multi-cellular, ingestive heterotrophs
• Lack cell walls but possess many cell membrane
  proteins
• Possess two unique types of cells
• Nerve cells
• Muscle cells

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Animal Characteristics

• Reproduce sexually with a dominant diploid stage

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Animal Characteristics

• Development
• Directly through transient stages
• Metamorphosis from larva to adult
• Hox gene
• Controls growth and development
• Guides cell division and differentiation

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Origin of Animals
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Common Ancestor of Animals
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Origin from Flagellates
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Neoproterozoic Era

• 1 billion 542 million years ago
• Ediacara fauna
• Fossils of radial forms many of whom bear legs
  and body segments

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Paleozoic Era

• 542 251 million years ago
• Cambrian explosion
• Reason??
• Predator-prey adaptations
• Increased oxygen

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Cambrian Explosion
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Paleozoic Era
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Mesozoic Era

• 251 65.5 million years ago

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Cenozoic Era

• 65.5 million years ago to the present

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Animal Body Plans
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Five Body Plan Features

• Type of Body Symmetry
• Number and Types of Body Tissues
• Presence or Absence of a Body Cavity
• Type of Developmental Mode

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Body Symmetry
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Number and Types of Tissue

• Germ Layers
• Ectoderm
• Endoderm
• Mesoderm
• Body plans
• Diploblastic
• Triploblastic

Ectoderm
Endoderm
Archenteron
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Presence of a Body Cavity
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Absence of a Coelom
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Protostome vs Deuterostome

• Cleavage Pattern
• Coelom Formation
• Fate of Blastopore

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Cleavage Pattern
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Coelom Formation
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Fate of Blastopore
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Phylogeny of Animals

• Based on
• Morphology
• Molecular Data
• Some agreement but also some differences
• Two family trees result

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Phylogeny based on Morphology
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Phylogeny based on Molecular Data
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Animal Phylogeny

• On-going!!

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Ecdysozoa
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Lophotrochoza