Transcript BIO 230 - Invertebrate Zoology

BIO 230 - Invertebrate Zoology
aka: ‘Everything you ever wanted to
know (and some stuff you didn’t) about
the little things that run the Earth.’
Classification of Life
• “Kids Playing Chicken On
Freeways Get Squished”
• What does this mean?
• Let’s start from the bottom…
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
Classification: Kingdoms of Eukarya
• Protozoa (often called Protista)
– Euglena, Amoeba, etc.
• Plantae
• Fungi
• Animalia
Fungi
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Unicellular or Multicellular
Eukaryote
Non-motile
Heterotrophs – no
photosynthesis
• Have a cell wall
• A subject of this class?
Plantae
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Multicellular
Autotrophs
Non-motile
Eukaryotes
Have a cell wall (cellulose)
A subject of this class?
Animalia
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Multicellular
Heterotrophs
Eukaryotes
Most are motile
No cell wall
A subject of this class?
Protozoa
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Mostly Unicellular
Many are colonial, many motile
Can be photosynthetic (autotrophs)
Some have a cell wall
A subject of this class?
Euglena
Amoeba
So, what is an invertebrate?
• It definitely includes animals…
• that simply lack vertebra (no true backbone)
But…
• Protists (amoeba, paramecium, euglena) blur
the line between animal and plant
• So we will consider organisms in Kingdoms
Animalia & Protozoa
• But mostly Animalia…
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
Inverts
• Incredibly diverse
• Most small but…
• Giant squid - 60 ft long &
>4,000 lbs
• Ribbon worms (nemerteans)
can grow up to 180 ft long
• At the other end, rotifers
mostly <0.001 mm smaller than
some bacteria
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
“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
Diversity of Invertebrates
Major Invertebrate Environments
• Marine
• Estuaries
• Freshwater
• Terrestrial
• Host organisms
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?
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
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
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
Low
High