# Osmoregulation in fresh water Protozoa # MSc # BSc # Zoology

1. D R . S H A M P A J A I N
P R O F E S S O R
D E P A R T M E N T O F Z O O L O G Y &
B I O T E C H N O L O G Y G O V T . M . H . C O L L E G E
O F H O M E S C I E N C E & S C I E N C E F O R
W O M E N , A U T O N O M O U S ,
J A B A L P U R , M . P . I N D I A
Osmoregulation in fresh water
protozoa

2. Osmoregulation in fresh water protozoa
Osmoregulation is the
process of maintaining salt
and water balance (osmotic
balance) across membranes
within the body

3. Surrounding environment
 Isotonic Medium –Example – Most of marine
animals and parasitic animals
 Hypotonic medium-ex fresh water animals
 Hypertonic animals –some marine animals
 Poikiloosmotic animals –Those aquatic invertebrates
whose internal osmotic pressure or concentration
changes according to external environment are
called poikilo osmotic animals.

4.  These animals are divided in to two groups .
 Stenohaline-Those poikilo osmotic animals that can
tolerate only slight changes in salinity are known as
stenohaline animals.
 Euryhaline animals - Those poikilo osmotic animals
that can tolerate wide range in salinity are known as
euryhaline animais.
 Homo osmotic-Those aquatic animals whose
internal osmotic pressure or concentration does not
change according to external environment.

7. Contractile Vacuoles in Paramoecium:
 In Paramoecium, two large contractile
vacuoles are present almost at the fixed
position one near each end of the cell.
One vacuole is located at the anterior
part and the other at the posterior part
of the body. Each vacuole consists of a
large central vesicle into which opens a
number of radiating or inhalant canals.

8. The radiating canal is divisible into three
parts:
 (i) Outer-terminal part,
 (ii) Middle-ampulla and
 (iii) Inner-injector canal.