Locomotion in Protozoa
Dr Nancy
Assistant Professor
Department of Zoology
PGGCG-42, Chandigarh
Locomotion in Euglena, Paramecium and
Amoeba
• Locomotion is the displacement of animals
from one place to another.
• Protozoa exhibit four types of locomotion.
• They are as follows:
Amoeboid movement
Ciliary movement
Flagellar movement,
and Metabolic movement
1. Amoeboid movement
• movement by means of pseudopodium is called amoeboid
movement.
• Amoeboid movement is a characteristic feature of Amoeba.
• But it is also exhibited by certain flagellates and sporozoans.
• Pseudopodium: Pseudopodium is a temporary projection of
cytoplasm formed on the body.
• There are four types of pseudopodia, namely:
• Lobopodia
• Filopodia
• Reticulopodia
• Axopodia
• 1. Lobopodia: These are lobe-like pseudopodia
with rounded tips. Eg. Amoeba, Arcella etc
• 2. Filopodia: Filopodia are filamentous pointed
pseudopodia. They are formed exclusively of
ectoplasm. They may be branched. Eg.
Euglypha
3. Reticulopodia (Rhizopodia): Filamentous pseudopodia that are
highly branched. Example: Globigerina, Chlamydophrys.
4. Axopodia: Stiff, pointed pseudopodia radiating from the body.
Each has a cytoplasmic sheath and axial rod. Example: Actinophrys,
Actinosphaerium.
Mechanism of Amoeboid Movement
• There are several theories explaining how amoebas move.
These are:
• Walking Movement Theory
• Rolling Movement Theory
• Surface-Tension Theory
• Sol-Gel Theory
• 1. Walking Movement Theory: Proposed by: Dellinger
(1906)Concept: Amoeba walks on a substratum using
pseudopodia as legs. The pseudopodium at the anterior (front)
end attaches firmly to the substratum. It contracts and pulls the
body forward. A new pseudopodium forms and attaches again,
continuing the movement. And the process is repeated.
• 2. Rolling Movement Theory: Proposed by:
Jennings. Amoeba moves by rolling its body on
the substratum. Movement is due to
cytoplasmic streaming. Example: Amoeba
verrucosa.
• 3. Surface-Tension Theory:
• Proposed by: Berthold. Pseudopodium is formed by
changes in surface tension at the body’s surface.
Protoplasm remains spherical due to surface tension.
Surface tension decreases at a point due to
internal/external changes.
Protoplasm flows out, forming a pseudopodium.
Amoeba moves in the direction of the pseudopodium.
• 4. Sol-Gel Theory: (Change of Viscosity
Theory)Proposed by: Hyman (1917)Most Accepted
Theory.
• Pseudopodium is formed by cytoplasmic phase
change from gel to sol and sol to gel.
Plasmalemma attaches to the substratum. Anterior
plasmagel converts to plasmasol. Posterior
plasmagel contracts, creating hydraulic pressure.
Pressure pushes plasmasol forward as a projection.
By the continuous accumulation of plasmasol, the
pseudopodium is formed.
At the periphery of the pseudopodium the plasmasol is
converted into the plasmagel.
The plasmagel of the posterior end is continuously changed
into plasmasol and it flows forwards.
This results in the withdrawal of pseudopodium from the
posterior end and helps the continuous supply of the plasmasol
to the developing pseudopodium at the anterior end.
By producing pseudopodia continuously in one direction in the
above manner, Amoeba slowly moves.
Formation of pseudopodium as proposed by sol-gel or Osmotic
theory
2. Flagellar Movement
• Flagellar movement is the swimming brought about by the
beating of flagella. It is exhibited by flagellates. Eg. Euglena.
• Flagellum
• Flagellum is a whip-like structure. Each flagellum has a
central axis called axoneme and a protoplasmic sheath. The
axial filament originates from a basal granule. The basal
granule is connected with the parabasal body or the
nucleus by a root-like structure called rhizoplast. Each
axoneme is formed of two central fibres and nine paired
peripheral fibres. Each peripheral pair bears a pair of short
arms. All the fibres are embedded in a matrix.
• The flagella bear small fibres on the sides. The fibres are called
mastigonemes. Based on the arrangement of mastigonemes, the
flagella are classified into the following types:
• Stichonematic flagellum: This type of flagellum contains a single
row of mastigonemes.Eg. Euglena.
• Partonematic flagellum: In this flagellum mastigonemes are
arranged in two or more rows.Eg. Paranema.
• Pentacronematic flagellum: This type of flagellum has two or more
rows of mastigonemes and a terminal filament.
• Acronematic flagellum: Here mastigonemes are absent, but a
terminal filament is seen.
• Simple flagellum: In this type, mastigonemes and terminal filament
are lacking.Eg. Chlamydomonas
• Flagellum with undulating membrane: In Trypanosoma, the
flagellum is provided with an undulating membrane.
Number of flagellum
• The number of flagellum in an animal may be
one or two or many.
• If these many flagella pulls the body forwards,
this flagellum is called tractellum.
• The flagella which are directed backwards are
called trailing flagella.
• Certain flagella situated at the posterior end of
the body are used to push the body forwards.
These flagella are called pulsellum
Types of flagellar movement
• The flagellum causes the animal to swim in
the water. The movement is brought about by
the oscillation of the flagellum.
• There are two types of oscillations of the
flagellum.
• They are as follows:
Rowing
Undulations
• Rowing:
• During normal locomotion, the flagellum beats. Each
beat consists of an effective stroke and a recovery stroke.
• During the effective stroke, the flagellum is held rigidly
with a slight concavity in the direction it is moving. This
stroke pushes the water backwards and the body
forwards.
• During the recovery stroke, the flagellum is relaxed and
well curved and is brought to its original position
passively. The flagellum beats obliquely. Hence, when
the animal moves, it rotates on its longitudinal axis
Undulations
• Sometimes wave-like movements
pass along the flagellum. These
movements are called undulating
movements (Fig. 8).
• When the undulations go from the tip
to the base the animal moves
backwards. When the undulations are
from the base to the tip the animal
moves forwards.
• As the organism moves, it moves in a
spiral path around a central axis. At
the same time the body rotates on its
own axis.
3. Ciliary Movement
• Ciliary movement is brought about by the beating of the
cilia. It is characteristic of ciliates. Eg. Paramecium,
Opalina, etc.
• Cilia
• Cilia are hair-like structures. They arise from basal
granules. Each cilium has a protoplasmic sheath and an
axial filament. The axial filament has the same structure
as that of the flagellum.
• The cilia are arranged in longitudinal rows. They may be
arranged all over the body uniformly or in restricted
areas. The row of cilia beat in a body transverse rhythm
called a metachronous field.
Mechanism of ciliary movement
Ciliary movement is very similar to that of flagellar movement. It
has also an effective stroke and a passive recovery stroke.
Ciliary movement
A. Effective stroke B. Recovery stroke
The cilia beat independently. All the cilia of the same body do
not beat at the same time. But all the cilia of a transverse
row beat at the same time. The cilia of a longitudinal row
beat one after another. This causes a wave-like movement of
cilia which is exactly like the movement of paddy in a paddy
field. This type of movement of cilia is called metachronal
rhythm.
4. Metabolic Movement
The metabolic movement is brought about by the contraction and relaxation of
the body. This type of movement is brought about by the presence of very fine
contractile fibrils present in the cytoplasm. These fibrils are called myonemes.
Metabolic movement is exhibited by flagellates, ciliates, sporozoans, etc.
• the metabolic movement carried out by Euglena
is called euglenoid movement.
• During this type of movement a peristaltic wave
of contraction and expansion passes over the
entire body from the anterior end to the posterior
end and the animal moves forwards.
• The body becomes shorter and wider first at the
anterior end, then in the middle and later at the
posterior end.
• This is brought about by the contraction and
relaxation of myonemes.
• Myonemes are situated longitudinally or
transversely or spirally in the cytoplasm.
