Important external features of fasciola hepatica are given below:
1. Shape and Size:
Fasciola is a dorso-ventrally flattened, soft, leaf like oval shaped endoparasite. It is about 1.8 to 3.0 cm long, with a maximum width of 0.4 to 1.5 cm. which is a little in front of the middle region of body. Anterior end is somewhat broad and rounded, while posterior end is bluntly pointed.
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2. Colour of the body:
Transparent body wall makes all the body organs to be visible. Due to this, the colour of the fluke appears pinkish.
3. Oral cone:
Anterior end of body is drawn out into a prominent conical projection, termed the oral cone or head lobe. At the apex of cone, a triangular mouth is found.
There are two small suckers, anterior and ventral. Both are devoid of hooks and spines.
(a) Anterior Sucker:
Anterior or oral sucker is a cup-shaped muscular organ with enclosed mouth at the centre of its bottom. The diameter of oral sucker is 1 mm.
Muscles of oral sucker radiate from margin of mouth to the periphery of sucker. Oral sucker serves for adhesion as well as ingestion.
(b) Ventral sucker:
Ventral sucker or acetabulum is bowl like situated mid ventrally behind the oral sucker. It is without an aperture and is of diameter 1.6 mm.
In front of acetabulum a small common genital aperture or gonopore is for fertilization. Another aperture, excretory pore lies at the posterior and slightly towards the ventral surface.
During breeding season a temporary opening of Laurer’s canal appears on dorsal surface, a little anterior to the middle of body. Digestive tract is incomplete without anus.
Body covered with cuticular tegument from which numerous minute spinules or scales appear. They serve for the anchoring of body to the walls of liver to protect and to help in locomotion.