Achilles Tangs, (Acanthurus achilles)
Chapter 4 –
Some Basics of Biology
• Organisms have precise chemical and physical
organization.
• All organisms require energy (the ability to do work)
to maintain themselves and grow.
• The large number of
chemical reactions that
sustain life can be
referred to collectively
as metabolism.
• Organisms use energy
to maintain
homeostasis, which is
maintaining stable
internal conditions that
are different from their
environment.
Ways of obtaining
energy
• Autotrophs –
capture energy from
the environment
and use it to make
glucose (a sugar);
Glucose is broken
down during
respiration and used
for growth, etc.
Photosynthesis is the most common way
organisms make their own energy.
Capturing energy from the sun to build
complex molecules.
Chemosynthesis uses chemicals in the
environment to build sugars, NOT sunlight.
Seen around hydrothermal vents.
• Heterotrophs – don’t make their own energy, they
consume other organisms and use stored energy
found in tissues for growth, etc.
Both heterotrophs and autotrophs both
engage in respiration as a process of using
the energy no matter what the source.
Primary Production
• Primary production is the net gain in organic matter
that occurs when autotrophs make more organic
matter than they need, usually by photosynthesis.
Only CO2, water and light are needed to make
glucose by photosynthesis but additional
materials are needed to convert the glucose
into other compounds.
Examples: Proteins, Lipids, nucleic acids
These raw materials are called nutrients.
Nutrients
Complex organic
molecules.
• Primary production requires nutrients as well as
light.
• Nitrogen and Phosphorous are usually the most
important nutrients for plant growth in the ocean.
Often the limiting factor for growth.
Slate Pencil Urchin (Heterocentrotus mamillatus)
Warm-Up 3/9
1. Why is primary productivity in an area
strongly associated with phosphorous and
nitrogen levels?
2. How do heterotrophs and autotrophs differ?
3. How are autotrophy and heterotrophs the
same?
Cellular composition
• Simple Cells
Prokaryotes
– Simplest and smallest cells (bacteria)
– No membrane‐bound organelles or nucleus
– Cell wall
• Complex Cells
Eukaryotes
– Nucleus with chromosomes
– Organized and complex
– Organelles with specialized functions
• Unicellular- One celled organisms that can carry out
all functions of life.
– Nearly all prokayotes are unicellular
• Multicellular- Multiple cells working together to
form an organism. Cells become specialized for
particular jobs.
– Nearly all multicellular organisms are Eukaryotic
Challenges of life in the sea
Salinity
• Diffusion- Movement of molecules from an area of
high concentration to one of low concentration.
– Whenever the internal composition of a cell differs from
that on the outside, substances tend to move in or out
of the cell by diffusions.
• Cell membranes are selectively permeable and allows
some substances to enter and leave the cell but blocks
others.
• Complex molecules cannot leave the cell, but water and
other small molecules can still easily pass through.
• Osmosis- diffusion of water across the cell
membrane.
• This movement of water must be dealt with for an
organism to survive in an aquatic environment.
Regulation of salt and water balance
• Osmoconformers- Organisms that don’t actively
maintain a salt and water balance. Their internal
concentrations change as the salinity of the
surround water changes
Blue-spotted Jawfish (Opistognathus rosenblatti)
Warm-Up 3/10
1. What is the difference between hypotonic
and a hypertonic solution?
2. How does diffusion pose a challenge to
animals maintaining homeostasis (life)?
3. Why don’t large molecules and proteins
diffuse out of cells?
• Osmoregulators- Control their internal
concentrations to avoid osmotic problems. Have
limits, but can tolerate salinity changes better than
conformers. Maintain an internal environment that
is different from the surrounding water
Marine Osmoregulation
•
•
•
•
Water lost via osmosis through skin and gills.
Water is replaced by drinking.
Actively excrete the accumulated salt via gills.
Produce small amounts of concentrated urine.
Freshwater Osmoregulator
•
•
•
•
Water gained via osmosis through skin and gills.
Do not drink.
Salt lost via diffusion. Actively collect via gills.
Produce high volumes of dilute urine.
• Marine birds, reptiles and some plants have special
glands that rid them of excess salt
Temperature Regulation
• Ectotherms – “cold‐blooded” generate heat through
their metabolism which is quickly lost to the
environment. Body temp is about the same as the
environment.
• Endotherms – “warm‐blooded” metabolic heat is
retained raising body temperature above
surroundings.
Surface to Volume Ratio
• Small organisms can lose body heat and materials
more rapidly than larger organisms
• The surface of a cell, its membrane, is the site of
exchange between its interior and its external
environment.
• This surface must allow sufficient exchange to
support the contents of the cell. Nutrient intake and
waste elimination both rely upon diffusion.
• As an object increases in size its volume increases as
the cube of its linear dimensions while surface area
increases as the square.
• As these cubes illustrate the surface area to volume
ratio of a small object is larger than that of a large
object of similar shape.
• This means that larger organisms must have
respiratory and excretory systems to compensate
for the larger volume as diffusion cannot occur
quick enough.
Methods of Reproduction
• Asexual (Vegetative) Reproduction
• Results in clones – genetically identical to parent
• Cell Fission and Budding
Fission
Sexual Reproduction
• Union of two different gametes (egg & sperm)
• Fertilization ‐ Results in genetically different
offspring (embryo)
• Egg – contains a lot of cytoplasm and the
organelles; yolk (nourish embryo)
• Sperm – head contains genetic material only
• Larval stage – present in most marine organisms
• Immature stages that an organism undergoes to
reach sexual maturity; usually visually completely
different than adult.
Crab Larva
Reproductive Strategies
• Reproductive Strategies refers to the Methods used
by a given species for reproduction and care of
young
Internal Fertilization
• Fertilization takes
place inside the
female body.
• Copulation is the
process of transferring
sperm from the male
to the female via a
specialized organ.
External Fertilization
Sperm unites with egg
in the open, rather
than inside specialized
organs within the
bodies of the parents
• Broadcast Spawning (External Fertilization) –
sperm and egg release in large numbers directly
into the water; no parental care
Barrel Sponge Releasing Gametes
Green Sea Urchin Releasing Gametes
Diversity of Life in the Sea
• There is a tremendous amount of diversity in the
oceans. How did it happen?
Theory of Evolution and Natural Selection
• (Charles Darwin – 1800’s)
• Best‐adapted individuals will produce more
offspring and pass on their favorable characteristics.
• Populations continually change in response to their
environments; they evolve (change over time)
Phylogenetics (Phylogeny) study of evolutionary
relationships among organisms
• Think of this as an extended family tree.
• You can use a family tree to figure out how closely
related you are to someone else.
• We are trying to figure out how closely related we
are to other species.
Cladogram:
– a tree‐shaped diagram showing evolutionary
relationships and the points where species appear to
have diverged from common ancestors
Classification of Living things
–Domain
–Kingdom
–Phylum
–Class
–Order
–Family
–Genus
–Species
(Dragon Kings Play Chess On Fine Gold Squares)
All of the organisms in the world are assembled
into three domains and six kingdoms
• Species:
– populations who share common characteristics
– Can breed with each other
– Produce fertile offspring
One Species
Many Species
Horse + Donkey = ?
Mule (Infertile)
Zebra + Horse = ?
Zorse (Infertile)
Dolphin + False Killer Whale = ?
Wholphin (fertility unknown)
Polar Bear + Grizzly Bear = ?
Grolar Bear
• Genus:
– Group of very similar species (ex. Felidae “cats”)
• Binomial Nomenclature:
– two‐name system of identifying organisms (ex. Homo
sapiens)
Weird scientific names
• There’s an entire genus of mites
named Darthvaderum. There’s even a wasp
named Polemistus chewbacca
• There are a couple of flies named Heerz
lukenatcha and Heerz tooya.
• In 2002, Neal Evenhuis named a bunch of flies,
including Pieza rhea, Pieza pi, and Pieza kake.
• Scientists say that Scaptia beyonce has a “large
golden bottom”