Question

Liver rot of sheep is caused by
(a) Fasciola hepatica
(b) Planaria
(c) Turbellaria
(d) Bipalium

Answer 1

Hint: It is a disease that is mostly caused in sheep and cattle. It is also known as liver fluke which is a parasitic worm infection. This disease is a plant borne trematode zoonoses which are classified as a neglected tropical disease (NTD). It can affect humans but is mainly hosted in ruminants such as cattle and sheep.

Complete answer:
 Fasciola hepatica causes the liver rot of sheep. It is a leaf-shaped worm which is also known as a liver fluke and is about 2 to 4 centimeters long. It grows in the liver of various animals and lays eggs which are passed through the bile duct and are excreted in the faces. If the eggs are exposed to the pools of water they get hatched after a few weeks and the larva finds their way into the small water snail. They get attached to the grass as a cyst. It resists drying when the water recedes and if they get swallowed with the grass or plants they migrate across the abdominal cavity and Pierce the liver. They get settled in the bile ducts and obstruct the flow of bile and inflammation in surrounding liver tissue.

Additional information:
Planaria: Planaria is a group of free-living flatworms that occur in freshwater in large masses. Some are marine and terrestrial whereas some f species are parasitic. They have an elongated body with a soft and ciliated leaf-shaped body. The ventral side consists of the mouth and the body cavity is absent. The fairings protruded from the mouth to the intestine and are usually blind.

Turbellaria: Turbellaria is a ciliated free-living animal with a few species which may be parasitic. They have about 3000 known species amongst which most of them are marine. They have a simple brain with an oval net extending from the out of the body and have no blood system. There are no organs for gaseous exchange and they reproduce asexually and sexually. They are hermaphrodites sexually.
Bipalium: Bipalium is a species of large Predator reel and planarians that have the distinctive shape of their head region. They possess a creeping sole on their ventricle side.they have a well-developed head plate with longitude lateral oracles and much broader than long. Bipalium is Predator re and prey on earthworms, molluscs depending on the species. They track their prey and when captured they react to the attack using the muscles in their body. They secrete sticky secretions to attach themselves to the prey and prevent escape.
So, the correct answer is '(a) Fasciola hepatica'.

Note: Fasciola hepatica is of great economic significance as they cause tremendous loss to the farmers of cattle and sheep. They cause liver rot and black disease to the cattle which are detrimental to livestock and are very hard to control in grazing animals liver fluke infection can cause the milk loss ab to 1 kg per day and over an electrician period of 300 days it creates a loss in milk production of about 300 liters per cow.