Animals

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Animals

• What characteristics define an animal?
• How do different invertebrates function?

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Why Study Invertebrates?

• THE major biotic component of the biosphere (96)

• Important part of every food web

• An important evolutionary link

• Model organisms in biology, medicine
• Anti-tumor agents from sponges
• Sea urchin genome - new information about how
• immune systems work

• Provide ecosystem services worth trillions of
• dollars per year pollination, seed dispersal,
  soil creation and aeration, decomposition, water
  purification etc., etc., etc.

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Vauxia gracilensis An early sponge
Hallucigenia A Crustacean?
Anomalocaris - an arthropod-like predator
Wiwaxia, a primitive mollusc?
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Remember the Cambrian Explosion?
PreCam.
Paleozoic
Cenozoic Mesozoic
Cam
Ord S Dev Car Per
Vendian
Cnidaria
Porifera Mollusca
Arthropoda Annelida
Echinodermata
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GOOD NEWS!
A single clam, mussel or oyster can filter up to
2 gallons of water per day!
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BAD NEWS!
Over 70 of all mussels are extinct or in trouble!
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Animalia are multicelled
have
are
carry out
with
such as
No cell walls
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3 Types of Body Plans

• Asymmetry
• Sponges - no plan!
• Folding increases their surface area

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Radial Symmetry

• Body parts radiate from the center -- mirror
  image any way you slice it!
• Kind of like a bicycle wheel

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Bilateral Symmetry

• Only one way to get
• two identical mirror images

• Left and right sides
• Anterior - Posterior
• Dorsal - Ventral

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RADIAL AND BILATERAL SYMMETRY IMPORTANT EVOLUTI
ONARY TRENDS
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COMPARE
Bilateral symmetry more mobile Sense organs
located on what end?
With all those sense organs we need a
concentration of nerve tissue to receive the info
and decide what to do with it! WHAT IS THAT
CALLED?
A BRAIN!

• CEPHALIZATION
• The degree of development of the brain.
• Another evolutionary trend!

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Cell specializationand tissue development

• Remember the SA/V ratio?
• V faster than SA
• Cell cant survive with simple diffusion

• Infolding -- sponges!

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Tissue layers
gastrovascular cavity
epidermis
gastrodermis

• Some animals
• developed an inner and outer layer of cells . . .

Others kept adding cells in one dimension
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• Tissues develop from embryonic germ layers

• The blastula (hollow, fluid-filled ball)
• folds inside itself, leaving an opening
• (the blastopore)
• now called the Gastrula

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• In protostomes (most invertebrates) blastopore
  becomes mouth
• In deuterostomes (Echinoderms and all
  vertebrates) blastopore becomes anus and mouth
  develops later

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In simpler animals folding of blastula makes 2
tissue layers

• Ectoderm (outside layer) skin nerve
• Endoderm (inside layer) respiratory digestive

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Complex animals - Third layer forms from the
endoderm

• Mesoderm
• Becomes muscles circulatory and excretory
  tissues
• Allows formation of a coelom
• (body cavity)
• Increasing complexity and diversity

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More Complex Animals Three tissue layers develop
Mesoderm forms from the endoderm
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COELOM FORMATION
Acoelomates no body cavity Coelomates body
cavity (coelom) w/ mesoderm on both
sides Pseudocoelomates fake body cavity w/
endoderm on one side and mesoderm on the other
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Major Evolutionary Trends

6. Cephalization
5. Body cavity
4. True gut (protostomes v. deuterstomes)
3. Symmetry
2 layers gastrovascular cavity
2. Tissues
1. Multicellularity
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• Tree of Life
• Fishes, amphibians, mammals, birds, reptiles
  make up only a single branch
• All other animal branches are invertebrates
• Represent the vast majority of our evolutionary
  history