Adaptations of Unicellular
Organisms
1.2.3: Explain how various structures of
unicellular organism help that organism
survive.
Essential Question:
How do adaptations in unicellular
organisms enable them to survive in their
environments?
1
Contractile Vacuole
• Vacuoles store materials
such as water, salts,
proteins, and
carbohydrates.
• In unicellular organisms like
paramecium, they contain a
vacuole called a contractile
vacuole.
– By contracting rhythmically,
this specialized vacuole
pumps excess water out of
the cell.
– This allows the cell to
maintain homeostasis or
balance.
2
Cilia
• Ciliates, like the paramecium,
use hairlike projections called
cilia for feeding and movment.
• Cilia propel them through the
water.
• They also line the organism’s
gullet and move its food to the
organisms interior.
– The food particles are engulfed,
forming food vacuoles.
– The contractile vacuoles collect &
remove excess water, which helps
to achieve homeostasis.
3
Flagella
• Some prokaryotic cells use
flagella to propel themselves.
• Flagella are whiplike structures
that are used for movement.
• Some eukaryotic cells have
flagella as well.
– Sponges carry out basic
functions, such as feeding and
circulation, by moving water
through their bodies.
– Choanocytes use flagella to
move water through pores in
the wall of the sponge and out
through the osculum.
– As water moves through the
sponge, food particles are
filtered from the water, and
wastes are removed from the
sponge.
4
Pseudopods
• Some eukaryotic organisms move
by temporary cytoplasmic
projections called pseudopods.
• Pseudopods are used for feeding
and movement.
• An ameoba is a type of organism
that uses pseudopods.
• These can also be called “false
feet.”
– The amoeba moves by first extending
a pseudopod away from its body.
– The cytoplasm then streams into the
pseudopod.
– This is a slow but effective way to
move from place to place.
5
Eyespots
• Plantlike protists, like
algae, possess a structure
called an eyespot.
• This is used to help the
algae find sunlight to
power the process of
photosynthesis.
• Flatworms have an
eyespot that can detect
changes in the amount of
light in their environment.
6