The document discusses various protozoan parasites that can infect shellfish, including Vorticella, Epistylis, Zoothamnium, Acineta, and Ephelota. It describes the appearance and effects of each protozoan, as well as symptoms they can cause like fuzzy growths on shells and gills. Maintaining good water quality and avoiding stressors can help prevent protozoan infections in shellfish farms.

1. Presented By :-
Saiprasad Bhusare
III Year, B.F.Sc.
College of Fishery Science, Udgir,
Dist : Latur, Maharashtra, 413 517.
Protozoa Disease in Shellfishes

2. Protozoan Fouling
1)Votricella
2)Epistylis
3)Zoothamnium Spp
4)Acineta
5)Ephelota
1)Fuzzy matt on shell and gill
2)Reddish to brownish gill.
 Causative Agent :
 Symptoms :

3. Protozoan Fouling
1)Microscopically protozoan are observed attached to any
external part of shrimp.
2)Protozoan cause respiratory and locomotory difficulties
when present in large number of the gills and appendages.
3)Particularly at low dissolved oxygen levels loss of appetite.
1)Maintain good water quality.
2)Avoid high organic load and low oxygen levels.
 Effect on Host :
 Preventive Measures :
 Treatment :
Improve pond environment and induce moulting.

4.  Vorticella is found in freshwater ponds, lakes, rivers
and streams with aquatic vegetation.
 It is worldwide in distribution.
 Vorticella is solitary and not colonial but usually
social, several of them being found together.
 It is commonly attached by a long highly contractile
stalk to some submerged objects like weeds, animals
and stones, etc.
Vorticella microstoma.
Vorticella

5.  Vorticella is often found in large groups.
 All the individuals in the group, however, remain free
and independent of each other.
 They are found in abundance in stagnant water rich in
decaying organic matter and feeds largely on bacteria.
 But V. campanula and V. nebulifera live only in
uncontaminated water where bacterial growth is not
good.
Vorticella

6. Epistylis
 The first observation of E. niagarae infests on freshwater Cyclops vicinus
living in Hazar Lake was reported by in 2008.
 In natural environments ciliate epibionts rarely produce mortality in their
crustacean basibionts.
 These can cause gill and surface fouling disease in shrimps at high densities,
typically under stress conditions.
 In some cases, they become opportunistic pathogens in culture ponds during
periods of low oxygen concentration.
 Present findings could represent that the ciliate protozoans act as epibionts
without causing any harmful effect on the host by giving contradictory views
of the above.
 The epibionts may leave the basibiont due to moulting. For this reason, the
protozoan epibionts like suctorian and peritrich ciliates may adapt their life-
cycles in such ways as moulting-induced reproduction and formation of
mobile stages which are able to reinfest the basibionts.

7. Epistylis
 The same genera of protozoans are located on different anatomical units of
different genera of crustaceans.
 Location of the protozoan on the host is specific and not random.
 Water currents formed by the hosts that carry food particles are exploited by
their epibionts .
 The larger colonies will occupy a larger surface area, thus preventing the
attachment of other colonies.
Epistylis niagarae

8. Zoothamnium
 It was studied in dominant mangrove crustacean species in several areas in
Malaysia.
 The observed basibionts were the crustaceans Acetes japonicus, Acetes
sibogae, Acetes indicus.
 Basibionts from the open sea area (Acetes japonicas) and from a sandy beach
of Penang (Mesopodopsis orientalis) showed the lowest epibiont densities.
 Considering all the colonized anatomical units each basibiont species had a
distinct epibiotic distribution and the epibiont species presented a
significantly different distribution over each of the basibiont species.
 Species sampled on mangrove and offshore areas also differed in this respect
The different epibiont species varied among locations according to the
structure of the community.

9. Acineta
 When another protozoan touches one of the sticky disks it remains glued
and immediately other tentacles are brought into play to immobilize it.
 A strange ballet begins if you observe carefully first, disks seem to dissolve
the protozoan cell membrane, then a sort of granulated flow is seen along
each tentacle from protozoan toward the suctoria, as if the protozoan
cytoplasm was transferred little drops by little drops.
 In a few minutes, the entire cytoplasm of the prey is phagocytized through
the suctorian tentacles.
 At the same time, cilia of the protozoan stop moving, and some minutes
later, an empty and retracted membrane of the protozoan is rejected.
 All the specimens shown here are marine organisms.

10. Ephelota
 Ephelota is a marine form, found in the sea water.
 The body is spherical and bearing a stalk.
 There are two types of tentacles on the body, viz., long pointed tentacles
used for piercing and short cylindrical for sucking.
 Protoplasm contains an oval nucleus and few contractile vacuoles.
 Reproduction by budding.
 The distal half of the animal may sprout a number of small elevations or
buds.
 In budding process the nuclei behave as in the ordinary, binary fission.
 The macronucleus extends into each bud and divides directly.

11. Bibliography
Manual of Avanti Feeds
Aquaculture - BlogSpot
www.Biologyduscussion.com
www.Zoology-quest.net
www.Google.com