Parasitic Adaptations in Helminths

Parasitic Helminthes flatworms lead parasitic life and will show several morphological and physiological adaptations.

Morphological Adaptations

To lead parasitic life many morphological adaptations are developed site.

1. Loss of organs
2. Formation of New organs
3. Modification of existing organs.

Loss of organs

Sense organs and locomotory organs are necessary for free-moving organisms but they are not useful for parasites. Hence they are lost.

1. Loss of Sense organs: Endoparasites have no sense organs.
2. Loss of Locomotory organs: The endoparasites have no locomotory organs. But the larval forms of some parasites may retain locomotory organs,
   1. In the life history of Fasciola hepatica - the miracidium larva will show a ciliated epidermis. So that they swim in the water in search of a snail.
   2. Tapeworms have no locomotory organs throughout their life.
3. Loss of digestive system: Tapeworms lead endoparasitic life in the body of human beings or vertebrate hosts. Their large, long flat body provides a good surface area to absorb organic food from the host hence there is no need for a digestive system. In all tapeworms digestive system is absent.

Formation of New organs

To lead parasitic life the organisms require additional structures.

1. Development of adhesive organs: To attach to the host body suckers in flukes, hooks, and suckers in tapeworms are developed
2. Cuticle: These parasites develop thick resistant cuticles to get protection from the digestive enzymes and antitoxins produced by the host.

Modification of existing organs

To lead parasitic life the existing structures are modified.

1. Flat body: The body becomes fiat and thin hence it can fit in narrow spaces of the host, it can absorb organic food and it can diffuse CO₂ from its body at a faster rate.
2. Shell around eggs: The fertilized egg is covered by a thick resistant shell, which will protect the embryo from desiccation, and high temperature.

Physiological adaptations

The parasites will show certain physiological adaptations to lead parasitic life they are

1. Anaerobic respiration: The endoparasites like tapeworms will perform anaerobic respiration.
2. Antienzymes: The tapeworms living in the intestine of the host will secrete anti-enzymes so that they can neutralize the enzymes of the host. Thus they can live in the intestine of the host.
3. Excessive reproductive Potential: The parasites continue their race during migration from one host to another and will produce thousands of shelled eggs. At least a few of them will reach the host and complete their life cycle.

They also show a complex life cycle with many larval stages. At every stage, the number will multiply so that the chance of continuation of the race is increased.

Thus parasitic flatworms will show parasitic adaptations.