BIO 230 - Invertebrate Zoology

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BIO 230 - Invertebrate Zoology

• aka Everything you ever wanted to know (and
  some stuff you didnt) about the little things
  that run the Earth.

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Classification of Life

• Kids Playing Chicken On Freeways Get Squished
• What does this mean?
• Lets start from the bottom

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Classification of Life

• 3 Domains are Bacteria, Archaea, Eukarya
• Bacteria/Archaea have prokaryotic cell types
• No nucleus
• No cytoskeleton
• No membrane-bound organelles
• Eukaryotes
• Both unicellular and multicellular
• Nuclei, cytoskeleton, and organelles present

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Classification Kingdoms of Eukarya

• Protozoa (often called Protista)
• Euglena, Amoeba, etc.
• Plantae
• Fungi
• Animalia

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Fungi

• Unicellular or Multicellular
• Eukaryote
• Non-motile
• Heterotrophs no photosynthesis
• Have a cell wall
• A subject of this class?

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Plantae

• Multicellular
• Autotrophs
• Non-motile
• Eukaryotes
• Have a cell wall (cellulose)
• A subject of this class?

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Animalia

• Multicellular
• Heterotrophs
• Eukaryotes
• Most are motile
• No cell wall
• A subject of this class?

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Protozoa

• Mostly Unicellular
• Many are colonial, many motile
• Can be photosynthetic (autotrophs)
• Some have a cell wall
• A subject of this class?

Euglena
Amoeba
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So, what is an invertebrate?

• It definitely includes animals

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• that simply lack vertebra (no true backbone)

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But

• Protists (amoeba, paramecium, euglena) blur the
  line between animal and plant
• So we will consider organisms in Kingdoms
  Animalia Protozoa
• But mostly Animalia

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Who cares about inverts?

• You should.
• Comprise about 98 of animal life on Earth
• Vertebrates 40,000 species
• Inverts 2 million described but as many as 8
  million still undescribed
• Found in basically all environments

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Inverts

• Incredibly diverse
• Most small but
• Giant squid - 60 ft long gt4,000 lbs
• Ribbon worms (nemerteans) can grow up to 180 ft
  long
• At the other end, rotifers mostly lt0.001 mm
  smaller than some bacteria

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Inverts

• Form part of the foundation of most food webs
• Pollinate flowers crops
• Cycle nutrients waste materials
• Important food sources
• Basically form the backbone of most ecosystems

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• If human beings were not so impressed by size
  alone, they would consider an ant more wonderful
  than a rhinoceros."
• "If invertebrates become extinct, the world as we
  know it would cease to exist."
• . the little things run the world.
• -- E.O. Wilson
• Professor Emeritus
• Harvard University

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Diversity of Invertebrates

• Major Invertebrate Environments
• Marine
• Estuaries
• Freshwater
• Terrestrial
• Host organisms

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Diversity of Invertebrates

• Land ca. 22 of surface area
• Water ca. 78
• Oceans - 97.3
• Lakes, ponds, reservoirs (lentic) - 0.009
• Rivers (lotic)
• So, not surprisingly most of invertebrate
  diversity is in the oceans
• Why else might this be?

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Life on land is challenging!

• Water...
• allows simple gas exchange across body surface
  (simpler respiration systems)
• prevents dehydration (no need for systems to
  prevent this e.g. worm mucus)
• provides movement of sperm and egg and allows for
  external fertilization
• flushes away waste
• is a versatile solvent makes nutrients
  available
• is less dense than air no need for rigid
  support and allows easy movement
• has high specific heat so temps are more stable

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But

• Light is in much shorter supply (extinguishes
  over a shorter distance)
• reduces primary productivity
• Air carries more oxygen than air
• Oxygen moves 30,000x faster in air
• Non-moving aquatic organisms need water flow!
• Water much more viscous so increases drag on
  larger animals
• Water sources collect wastes

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Influences on Invert Diversity
Property Air Water
Humidity High Low
Density High Low
Specific Heat High Low
O2 solubility Low High
O2 diffusion Low High
Nutrient content High Low
Light Extinction High Low