Parasites metazoan (cestode, nematode,acantho)

taxonomy, morphology, lifecycle and 2species

1. Name ; S.J.Abisha Juliet Topic : Metazoan Parasites

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

3. Cestodes,Nematodes , Acanthocephalan, Glochidia

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

8. 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

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

10. 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

11. 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)

12. 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.

13. 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.

14. 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 .

15. 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 ,

16. 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

17. 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 .

18. 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

19. Nematodes 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.

20. 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

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

22. 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

23. 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.

24. 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 )

25. 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 ).

26. 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

27. 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

28. 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

29. 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

30. 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.

31. 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

32. Parasites of marine tropical fishes Crustaceans – 1 st 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

33. Parasites of Elasmobranch Very small no Only 68 sp Most belongs to 2 families Heterocheilidae of order Ascanididae 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 )

34. Acanthocephalan 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.

35. 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 .

36. 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

37. 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 .

38. 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.

39. 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

40. 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

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

42. 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 Pomphorhynchus & Echinorhynchus found in marine Rarely encounterd in Reef fishes Adult – intestine Host – 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

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

44. 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 Mussel

45. 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

46. 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

47. 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

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

49. Thank you