taxonomy, morphology, lifecycle and 2species

2. Metazoa(worms and arthropods)
Phylum- Platyhelminthes
Phylum- Arthropoda
Phylum- mollusca
My Topics
Phylum - Platyhelminthes
Cestodes
Nematodes
trematodes
Acanthocephala
Phylum- mollusca

4. •Endoparasites
•Atleast one intermediate host in their lifecycle
•Harbours on most wild and many cultured fish
Shape -Tape-like; segmented
Sexes -Not separate,i.e.,Hermaphrodite
(monoecious)
Head space -Suckers, often with hooks
Alimentary canal -Absent
Body cavity -Absent

5. Taxonomy
Phylum- Platyhelminthes
Class – Cestoda
Group- Cestodaria Eucestoda
2 orders 11 orders
Gyrocotylidae Caryophilidae
Amphilinidae Pesudophilidae
Proteocephalidae
Cestodaria- monozoic ie. Unsegmented
Eucestoda- Polyzoic ie. Segmented
Order Tetraphyllidae
Trypanorhyncha very common in Elasmobranch

6. Amphilinidae
• Small group have 8 species
•Gigantolina magna – parasite of marine
teleost
•All other species infect freshwater teleost
and turtles
•10 larval hooks
Gyrocotylidae
•10 known species
•Intestinal parasites of the entirely marine
holocephali
Pesudophyllidae – 50% marine
Tetraphyllidae - 95% marine
 Trypanorhyncha -95% marine

7. 1. Caryophyllidea (Caryophyllaeus and Khawia),
2. Pseudophyllidea (Ligula, Schistocephalus, Diphyllobothrium and Triaenopho
3. Proteocephalidea (Proteocephalus spp.).
The cestode genus Proteocephalus occurs worldwide; however, very
little is known about the mechanisms of species distribution within the
host range.

9. Morphology
•Adult worm white in color
•Very elongated
Body or Strobila – Flattened
Cephalic portion of Strobila differentiated into an attachment
organ Scolex
Cestodaria – No Scolex

10. Scolex has specialised attachment
structures such as
• Hooks,
•Sucker like organs( Bothria, Bothrium,
Acetabula)
•Spined tentacles
•Apical organ

11. •Apical organs composed of Muscular /
granular elements
•Proteins, lipids , glycoproteins were
detected within the granules
•Scolex is followed by
Neck(undifferentiated part of Strobila)
•Scolex has germ cells that generates new
Segments – Proglottids

12. Maturation of Segments
Apolytic Cestodes – Gravid segments
Enapolytic Cestodes – Mature but non
gravid segments
Hyperpolytic cestodes – Immature segments
No digestive tract because there is no Body cavity or Coelom
Body covering of Cestode – Tegument
Synctial structure
With surface modification in the form of
• Gylcocalyx
• Microtriches
Rich in Phospholipids (phosphotidylcholine is abundant)

13. Lifecycle
Fish can serve as Intermediate and Definitive host for tapeworms
All cestodes are Oviparous
The plerocercoid is long - lived in the fish host, which can
accumulate parasites throughout its life.

14. The magnitude of size increase is spectacular in
larval Ligula and Schistocephalus, where, in the
body cavity of the fish, the biomass of the parasite
may reach 40% of the body weight of the host.

15. One of the most serious adult
cestodes that affect fish is the
Asian Tapeworm –
Bothriocephalus acheilognathi
Ligula intestinalis in a cyprinid
Ligulids have a global distribution, mainly
as parasites of cyprinid and catostomid
fish.
Species of Diphyllobothrium in fish have a
similar life cycle to that of the ligulids but,
except for D. latum , the broad fish
tapeworm of humans, the plerocercoid
stage is typically found in salmonids and
coregonids.

16. Diphyllobothrium spp. infection in the peritoneal cavity of a brown trout. A
feature of such infections is the severe fibrinous peritonitis that is
induced by the plerocercoids.
Diphyllobothriid
plerocercoids
become encysted
amongst the
viscera and in
the musculature
of the fish,

17. Parasites of Freshwater Tropical Fishes
Like Digenetic trematodes rarely affect the ornamental fishes as adult
worms
Wild caught ornamental fish serves as Secondary intermediate host
Result – Poor growth,
Emaciation
Lake trout fillet with Cyst

18. Parasites of marine
Tropical Fishes
Adult cestodes -harmful parasites in
Digestive tract
Plerocercoids greatest concern in
marine
Larvae of Tryphanorhynca - Spagetti
worms in Drummers of Gulf of
mexico
Wormy couta- in Austrailan barracuda
– larvae of Gymnorhynchus thyrsites
Rainbow trout with a massive
infection of Diphyllobothrium
dentriticum plerocercoids ( arrows ).
The larvae are encapsulated mainly
around the stomach and pyloric caeca

19. Parasites of Elasmobranch
Common in spiral valves
400 described sp of cestodes from Shark,Skate and
Ray
Harbours on digestive tract
Intermediate host – fish, gastropod, crustaceans
Final host - Shark,Skate and Ray
No mortality due to cestode
infestation in shark
Pathology
 cavitation
Localized hemmorhage
Compress of intestinal microvilli

20. Common parasite of both Marine and Fresh water
fishes.
 Although parasitic nematodes can infect almost all
organs in a fish, the majority of the currently known
species have been described from the intestine.
Adult worm in the ovary
. Liverwith encysted, anisakid,
nematode larvae.

21. • Shape Elongated, cylindrical;
unsegmented
• Sexes Separate (diecious)
• Head space No suckers, no
hooks. Well developed
buccal capsule in
some species
• Alimentary canal Present and
complete;
• Anus present
• Body cavity present

22. Taxonomy
Phylum – Nematoda
Class - Adenophorea Secernentea.
Families- Dioctophymatidae,
Capillariidae
Cystiopsidae
i. Adenophorea consist mostly of free-living
marine and freshwater species, as well as
terrestrial soil nematodes with only a small
number of parasitic organisms
ii. Secernentea also have free-living taxa, but
the vast majority of this class are parasitic
organisms.

23. Morphology
Generally elongated worm with cylindrical body tapering at the
both ends - fusiform shape
Most fish nematodes are a whitish to tan color
Some are Reddish due the color of Pseudocoelomic fluid
•Pseudoterronova larvae – own heamoglobin
•Camallanus sp – from feeding on host blood
Swim bladder worms ( Anguillicola ).
Dark color is due to feeding on blood

24. The cuticle of nematodes
 is elastic, and it is thick in gut-dwelling species (Hysterothylacium,
Eustrongylides) and
relatively delicate in histozoic specimens (Philometra rischta,
Daniconema anguillae)
External surface
• smooth
• some have row of spines on their cuticle
(eg;Spintetctus, Gnathosoma)
Body wall lacks Circular muscle
Body covered by Collagenous Cuticle shed periodically in life of
nematodes by Ecdysis
The cuticle are without cilia.

25. •Mouth have lips may prominent in later larval stages and reach their
full expressions in adult
The structure of the mouth shows
great variations.
It may be a simple slit-like opening at
the anterior end surrounded by
distinct or indistinct papillae
(Capillaria, Philometra), but it can
form large labia or cuticular
outgrowths (Fig) called Interlabia
(Hysterothylacium, Anisakis,
Raphidascaris)

26. The mouth leads into the buccal capsule
(Figs12.7and12.8),which can be sclerotized and
furnished with large denticles, ridges, plates or tridents
(Camallanus, Cucullanus, Skrjabillanus, Anguillicola).

27. Some have teeth guarding
the rim of mouth
( Anguillicola)
Most of them posses sensory
structures such as papillae that
surround the mouth and the
anterior end which serve as
chemoreceptors

28. The male reproductive organ usually
consists of testis, vas deferens,
seminal vesicle and ductus
ejaculatorius.
The ejaculary duct, opening into the
cloaca, has some accessory copulatory
organs.
The most common accessory organs
are the sclerotized spicules.
Mostly 2 Spicules
Angullicola-nil
Capillaridae-1

29. The female reproductive organs are composed of ovaries, oviducts,
uteri, vagina and vulva.
 In Capillaria and Raphidascaris spp - the vulva is found in the first
part of the body length,
 but in Camallanus and Rhabdochona spp -posteriorally.
The Capillospirura -at mid-length.
In adult Philometra spp -the vulva and vagina are absent
They do not have protonephridia, respiratory organs or blood
systems
Female nematodes are usually larger than males
Life cycle
Most fish nematodes are Oviparous

31. Camallanus spp
Easily recognised as small thread like worm protruding
from anus of the fish
Capillaria spp
Large round worm
Commonly found in the gut of angel fish
Often recognised by its double operculated eggs in the female worm

32. Eustrongylides
Eustrongylides is a nematode that uses fish as its
intermediate host. The definitive host is a wading bird, a
common visitor to ponds. The worm encysts in the peritoneum
or muscle of the fish and appears to cause little damage.
Because of the large size of the worms ( Figure ), infected fish
may appear unsuitable for retail sales.

33. Parasites of freshwater tropical fishes
No genera associated with freshwater tropical fishes.
Eustrongyloides- encysted in muscles
Capillaria- frequently found in FW
Camallanus- Guppies and swordtails seem to be most frequent
Adult & larval forms – in lumen of intestine
Free migratory forms – peritonieal Cavity
Encysted forms – in musculature
Heavy and moderate infections with
Anguillicola crassus in opened swim
bladders of European eels

34. Parasites of marine tropical fishes
Crustaceans – 1st intermediate host
Ascaridoidae- Anisakis, Contracaecum, Terranova
Spiruroidae – Ascarophis, metabronema
Camallonoidae- Aslanus, Camallanus
Dracunuloidae- Philometra, philonema
Common pathology
visceral adhesion
Edema
Granuloma
Philometra oviata in gudgeon
Heavy infestation reported in White spotted puffer fish from Hawaiian waters

35. Parasites of Elasmobranch
•Very small no
•Only 68 sp
Most belongs to 2 families
1. Heterocheilidae of order Ascanididae
2. Cucullanidae of the order of Spiruridae
Primarily in digestive tract
 visible nodules on the exterior of the intestion
Nematodes of shark require atleast one intermediate host usually
Crustaceans
Second intermediate host – fish (Pleuronectidae, Gadidae)

36. Thorny or Spiny
headed worms
They are mostly
elongate
cylindrical worms
 Armed with an
anterior retractile
proboscis bearing
hooks in a large
variety of patterns.
There is no gut and
the sexes are
separate.

37.  Acanthocephalans are Endoparasitic worms.
 Found as adults in the intestine of fishes.
 Juvenile worms of many other species occur in the
viscera, especially the mesentery and liver, of fishes
Diagram of typical adult
acanthocephalan.
Acanthocephalans
embedded in the
intestinal mucosa of a
fish.

38. Taxonomy
Phylum Acanthocephala
The acanthocephalans comprise four classes, and only two
of which, the Palaeacanthocephala and Eoacanthocephala,
contain members parasitic on fish.
Many species occuring in marine environment show more
extended distributional range than those being transmitted in
freshwater.
The species Acanthocephalus lucii and A.anguillae use the same
intermediate host, the isopod Asellus aquaticus

39. Morphology
Body has
• Presoma(Proboscis and neck) inserted into
the intestinal wall
•Metasoma (trunk) lying inside the intestinal
lumen of the final host
•Proboscis- major holdfast organis usually kept
semi-invaginated
.

40. The neck is usually short and
inconspicuous, but in some genera
it is extremely elongated and may
be inflated to form a bulb.
Body wall is thick tegument
which is a syncytium
Females are larger than males
 Body length of adults varies
greatly among species, ranging
from less than 2 mm to greater
than 700 mm. Acanthocephalans of
most species are about 10 mm
long.
The structure of acanthocephalans.
(A)Adult male. (B) Adult female.

41. Metasoma is lined by Glycocalyx- to absorb CHO and aminoacids from
lumen of the host gut
The different depth of penetration coincides with a morphological
feature
The perforating species A.Anguillae has long neck while the neck is short
in the non-perforating congener
 The remainder of the body is a trunk, which, in some species, bears
tegumental spines, which may enhance attachment to the host intestine

42. The genital pore occurs posteriorly on the trunk, and
in males it is surrounded by an invaginable bursa
In males there are two testes followed posteriorly by
one to eight cement glands
Embyonated eggs are sorted by egg sorting organ
Like tapeworms, Acanthocephalans dont have an
intestine.
Scanning electron micrograph
of an egg showing
unwrapping of egg
membranes

43. At least one intermediate arthropod host is required in the life cycle

45. Parasites of freshwater tropical fishes
•Major problem in wild FW or marine fishes
•Incidence in ornamental freshwater tropical fishes is low
•Parasite load is very low
•Generally 1or 2
•Intermediate host – wild caught ornamental fish
•Final host- bird or large fish
Parasites of marine tropical fishes
oPomphorhynchus & Echinorhynchus found in marine
oRarely encounterd in Reef fishes
oAdult – intestine
oHost – amphipod
Parasites of Elasmobranch
Harmful effects on bony fishes Not responsible for mortalities
Infection in elasmobranch is rare
Only one sp is reported in Spiny dogfish

46. Photograph of Acanthocephalus dirus
attached to the prolapsed rectum of a
mottled sculpin

47. The glochidia larvae of fresh - water bivalve molluscs are
often found attached to the gills and outer surfaces of fish.
The larvae have thin bivalve shells often with little hooks
on their inner edge

48. Morphology
Shells are small,spherical or oval
Laterally compressed
Byssus thread
Has sharp spines projecting
inward from each valve
It lures fish close by exposing a
piece of their mantle in the water

49. Once the glochidia are released from the female, they
must attach to the gills or the fins of the right fish host
and encyst to complete development. Otherwise they
won’t survive.
Taxonomy
Kingdom; Animalia
Phyllum: Mollusca
Class; Bivalvia
Family: Unionidae
Margaritiferidae

50. Glochidia, undergo an
obligatory parasitic phase
on fish.
The glochidia are released
from the adult mollusc and
If they come into contact
with a suitable fish they
clamp on to the gills, fins or
skin, become surrounded
by host tissue and in time
undergo a metamorphosis
to form a juvenile mollusc.
These are eventually shed from the fish and grow to maturity as
free - living molluscs. Glochidia may remain on the fish for several
months

51. References
1. Fish disease and Disorders Volume 2 by P.T.K. Woo
2. Fish pathology – 4 th edition By Roberts
3. Introductrion to Freshwater Fish Parasites by RuthEllen
Klinger and Ruth Francis Floyd
4. Fish Disease- Volume 2 By Jorge C.Eiras , Helmut
Segner, Thomas Wahli, B.G. Kapoor
5. Fish Disease diagnosis and treatment by
Edward.J.Noga
6. Marine parasitology Edited by Klaus Rhode