Biology

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  • Topic: Cestoda, Flatworm, Digenea
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  • Published : February 19, 2013
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Notoplana acticola
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Turbellaria
Order: Polycladida
Family: Leptoplanidae
Genus: Notoplana
Species: acticola

Fasciola hepatica
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Echinostomiformes
Family: Fasciolidae
Genus: Fasciola
Species: hepatica

Taenia solium
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestoidea
Order: Cyclophyllidea
Family: Taeniidae
Genus: Taenia
Species: solium
Amphibdella flavolineata
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Monopisthocotylea 
Family: Dactylogyridae
Genus: Amphibdella
Species: flavolineata

Entobdella soleae
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Monopisthocotylea
Family: Capsalidae 
Genus: Entobdella
Species: soleae

Taenia saginata
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestodes
Order: Cyclophyllidea
Family: Taeniidae
Genus: Taenia
Species: saginata
Polystoma integerrimum
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Monogenea
Order: Polystomatoinea
Family: Polystomatidae
Genus: Polystoma
Species: integerrimum

Paragonimus westermani
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Plagiorchiida
Family: Troglotrematidae
Genus: Paragonimus
Species: westermani

Opisthorchis parasiluri
Phylum: Platyhelminthes
Class: Trematoda
Order: Opisthorchiida
Family: Opisthorchiidae
Genus: Opisthorchis
Species: parasiluri

Platyhelminthes(Background Information)

Platyhelminthes (plăt´ēhĕlmĬn´thēz), phylum containing about 20,000 species of soft-bodied, bilaterally symmetrical, invertebrate animals, commonly called flatworms. There are four classes: the free-living, primarily aquatic class, Turbellaria, and Trematoda, Cestoda, and Monogenea, which are considerably modified for their exclusively parasitic existence. While the structure of the flatworms marks a major step in animal evolution, their origin and relationships within the group are still controversial.

Anatomy

Flatworms are dorso-ventrally flattened. The epidermis is generally ciliated in the turbellarians, while trematodes and cestodes are covered with a cuticle. Beneath the outer covering are two layers of muscle, an outer circular layer, and an inner longitudinal layer; this arrangement permits an undulating form of locomotion that can be observed in the larger turbellarian species. A saclike digestive cavity, with a single opening to the outside that serves as both mouth and anus, is sometimes present; in the simpler forms it is absent or unbranched, but in higher forms it branches to all parts of the body. The major sense organs, when present, are concentrated in the head, or front end. Although a primitive nerve net is present in some of the simpler forms, others have several nerve cords extending from a brain along the length of the body. The latter pattern of organization is retained in the nervous systems of higher invertebrates, specifically annelids and arthropods.

The reproductive system of flatworms is characteristically hermaphroditic (i.e., each individual produces both eggs and sperm), and cross-fertilization between individuals is typical. While trematodes and cestodes shed eggs almost continuously, turbellarians exhibit seasonal reproductive activity and, in addition, display asexual reproduction and the ability to regenerate severed parts of the body.

All except the simplest flatworms have nephridial tubules, called protonephridia, usually distributed throughout the body. Such structures consist of an external opening and a tubule that branches internally, terminating in a number of blind, bulb-shaped structures called flame bulbs, which bear tufts of cilia. They probably function as excretory and osmoregulatory organs.

Class Turbellaria

The mostly free-living, primarily carnivorous, flatworms of class Turbellaria are characterized by a soft...
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