Shark embryo, Squalus acanthias

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Fundamentals of Biology
Shark embryo, Squalus acanthias
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What does it mean to be alive??

• You may find that your definition, or view, of
  life differs radically from your neighbors.
• You wouldnt be alone there. Most scientists
  cant agree on it either!
• Todays material will cover the basics of
  biology.

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What Scientists Do Agree Upon

• Life uses energy for metabolism
• Life maintenances itself (homeostasis).
• Life grows
• Life reproduces
• Life reacts to changing conditions
• Life finds a way!!

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What does it take?

• If you are trying to determine what it takes to
  be alive what would you do?
• Water would be a good starting point.
• Most organisms are composed largely of water.

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Where to go next?

• Organic molecules also play a major role in life
  processes.
• Organic molecules are those which contain a
  source of carbon (except CO2 which is still
  considered inorganic), hydromen, and oxygen.

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• Most of these simple
• organic molecules
• are organized into more
• complex molecules
• such as proteins,
• carbohydrates,
• and lipids (fat).
• This is done in order to
• manipulate energy stored
• within the molecules.

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Just imagine how much energy is stored in this
whale blubber (fat).
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• Conversely, equal
• amounts of energy may
• be stored within the cellulose
• walls of this giant kelp in the form
• of carbohydrates (sugar).
• Carbohydrates are common in
• the marine environment for energy
• and for structure.
• They are also found inside and
• outside of animals (chitin in shells).

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• Other organic compounds of great importance are
  proteins.

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• Proteins consists of
• amino acids which
• contain nitrogen.
• Proteins are used as
• building blocks for
• tissues such as
• muscles and nerves.
• They are also used for
• hormones

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• and even antifreeze!

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Other necessities

• In addition to proteins, carbs., and lipids,
  organisms rely on DNA, RNA, and ATP to transfer
  genes, build proteins, and store energy,
  respectively.
• ATP is extremely important because it serves as
  energy currency for most cells.

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Most energy used by organisms originates from
photosynthesis.
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• Photosynesis makes it and respiration takes it!!
• Each process is essentially the reverse of the
  other.

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Photosynthesis and respiration combine to
facilitate primary production. Primary producers
are photosynthetic organisms for the most
part. Each relys on Nitrates (NO3-1), phosphates
(PO4-2), and occasionally silica (SiO2).
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Cells, or the basic unit of life, contain a
nucleus, and various cellular organelles which
carry out cell specific functions. In addition
to the organelles listed certain bacteria also
contain motility structures called flagella or
cilia.
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Sometimes, all you need in life is one cell,
especially if youve got 10,000 buddies just like
yourself!! (The first labor unions???)
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Challenges to life!
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Introduction

• Maintaining steady-state equilibrium in the
  internal environment of aquatic and marine
  organisms is challenging.
• Much is done involuntarily (hormones, enzymes,
  osmoregulation, etc.) so little physical action
  is required, however
• Pick-up-and-move still an option!
• (Poor environment.)

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Definitions

• Homeostasis maintaining steady state
  equilibrium in the internal environment of an
  organisms
• Solute homeostasis maintaining equilibrium with
  respect to solute (ionic and neutral solutes)
  concentrations (i.e. salts)
• Water homeostasis maintaining equilibrium with
  respect to the amount of water retained in the
  body fluids and tissues

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Osmoregulation in different environments

• Challenge to homeostasis depends on
• Solute concentration of body fluids and tissues
• concentration of environmental solutes
• marine 34 ppt salinity 1000 mosm/l
• freshwater lt 3 ppt salinity 1 - 10 mosm/l

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Osmoregulation in different environments

• Each species has a range of environmental osmotic
  conditions in which it can function
• stenohaline - tolerate a narrow range of
  salinities in external environment
• euryhaline - tolerate a wide range of salinities
  in external environment
• short term changes estuarine - 10 - 32 ppt,
  intertidal - 25 - 40
• long term changes diadromous fishes (salmon)

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Four osmoregulatory strategies in fishes

• 1. Isosmotic (nearly isoionic, osmoconformers)
• 2. Isosmotic with regulation of specific ions
• 3. Hyperosmotic (fresh H20 fish)
• 4. Hyposmotic (salt H2O fish)

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Osmoregulation Strategies

• Osmoconforming (no strategy) Hagfish internal
  salt concentration seawater. However, since
  they live IN the ocean....no regulation required!

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Osmoregulation Strategies

• Elasmobranchs (sharks, skates, rays, chimeras)
• Maintain internal salt concentration 1/3
  seawater, make up the rest of internal salts by
  retaining high concentrations of urea
  trimethylamine oxide (TMAO).
• Bottom linetotal internal osmotic concentration
  equal to seawater!
• How is urea retained?
• Gill membrane has low permeability to urea so it
  is retained within the fish. Because internal
  inorganic and organic salt concentrations mimic
  that of their environment, passive water influx
  or efflux is minimized.

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Osmotic regulation by marine teleosts...

• ionic conc. approx 1/3 of seawater
• drink copiously to gain water
• Chloride cells eliminate Na and Cl-
• kidneys eliminate Mg and SO4
• advantages and disadvantages?

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Saltwater teleosts
kidneys
chloride cells
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Osmotic regulation by FW teleosts

• Ionic conc. Approx 1/3 of seawater
• Dont drink
• Chloride cells fewer, work in reverse
• Kidneys eliminate excess water ion loss
• Ammonia bicarbonate ion exchange mechanisms
• advantages and disadvantages?

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Freshwater teleosts
Ion exchange pumps beta chloride cells
kidneys
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Thermoregulation in Fishes
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Temperature is always an issue.
It affects metabolism, digestion, and
reproductive behavior
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Fish are conformers (well, sort of...)

• Body temperature is that of the environment
  (poikilothermic ectothermy)
• Each species has particular range of temperatures
  that they can tolerate and that are optimal
• Big difference!

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Behavioral Thermoregulation in Fishes

• Although fish are ectotherms, they can alter
  their body temperature by moving to habitats with
  optimal temperature
• Some fish can maintain body temperature greater
  than ambient - tunas, billfishes, relatives
  (nearly endothermic)

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Hot Fishes

• Billfishes have warm brains excess heat
  production from muscles around eye

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Size matters when youre small!!! Animals with
high surface to volume ratios dont hold heat.
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• Floyd, I am soooooooo tired, how long can this
  go on?
• -Heavy Metal (80s)
• Life moves pretty fast, if you blink you just
  might miss it.
• -Ferris Buhlers Day Off (90s)

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Budding in coral allows multiple replications of
the same entity. Since coral uses itself as a
template, this is a form of asexual reproduction.
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Rhizomes (runners) sent from sea grass is another
example of asexual reproduction.
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Sexual reproduction Union of two gametes.
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Reproductive strategies mayinvolve mass
production of young
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or single offspring with a high degree of
parental care.
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Next timereal animals and real names.