Protists are eukaryotic, unicellular
organisms that simply do not fit into
any other kingdom.
They can be categorized as:
1. Animal-like (Protozoans)
2. Fungus-like
3. Plant-like
• Animal-like protists, often called protozoans, are
heterotrophic.
• They commonly consume other organisms for
food and a number of them are parasites, taking
nutrients from the organism in which they reside.
• Protozoans can be broken down into 4 basic
groups:
1. Cercozoans
2. Ciliates
3. Flagellates
4. Sporozoans
The most common cercozoan is the amoeba, often times characterized by their pseudopods or “false feet” used to eat or move.
• Ciliates have many short, hair-like projections that cover the surface of the cell, that are used for sweeping food particles and for locomotion.
• The paramecia is the most common ciliate.
These protists have
long, hair-like
projections extending
from the cell
membrane known as
flagella.
The flagella are used in
a whip-like motion to
propel protists.
These protists are parasitic and take
nutrients away from their host.
Malaria is a deadly disease caused
by the sporozoan in the Plasmodium
genus living between two hosts:
humans and mosquitoes.
Heterotrophic organisms that feed by means of absorbing nutrients from other living things, dead organisms, and wastes.
They also produce spores (like fungi). Major groups include slime moulds
(plasmodial and cellular) and water moulds.
These organisms contain pigments
in their chloroplasts, enabling them
to carry out photosynthesis.
Unicellular plant-like protists
include: 1. Diatoms
2. Dinoflagellates
3. Euglenoids
Diatoms, such as
phytoplankton, are
single-celled, free-
floating aquatic
organisms usually
reproduce asexually,
but under certain
conditions can
reproduce sexually.
Most dinoflagelletes are also phytoplankton,
but they also have two flagella at right angles to
each other allowing these organisms to spin
through the water.
Under ideal conditions, they are responsible for
algal blooms (red tides).