Question

Animals living and subsiding on other animals is called
(a) Pathology
(b) Parasitology
(c) Parazoology
(d) Protozoology

Answer 1

  Hint: In nature, animals, plants, and microbes do not and can not occur in isolation. They interact in various ways to form a biological community. Such interactions sometimes can be Detrimental. When an animal lives on other animals and derives nourishment only one species is benefited whereas another one suffers.

Complete Step by Step Answer: A parasite is an organism that lives on and derives nourishment from the other organism. And this phenomenon is known as Parasitism. The study of these parasites, habitat, and their interactions with the environment is known as Parasitology. Like predation, in parasitism, only one species benefits (parasite), and the interaction is detrimental for the other species on which it lives (host).
So, the correct answer is, ‘(b) Parasitology’.

Additional Information: There is no known natural habitat on earth that is inhabited just by a single species. There is the interaction between two or more organisms which is important for sustainability. Parasitism is a relationship between two organisms, where one organism spends a part or whole of its life, on or in the body of another organism, and gets nourishment and shelter from the second organism.
There are many adaptations done by parasites. These are:
- Presence of adhesive organs or suckers to cling on the host.
- Loss of unnecessary organs.
- Loss of the digestive system.
- Some show a complex life cycle.
Impact on host:
- Parasites may reduce the survival rate of the host.
- They render the host more vulnerable to the other infection as it weakens the host’s body physically. Parasites are of two types:
Endoparasites: These parasites live inside the body of the organism in different sites.
Ectoparasite: These parasites live on the external surface of the host organism example, lice, leech.

Note: 
- Parasites have evolved in many taxonomic groups from plants to higher vertebrates.
- Parasites and hosts both tend to co- evolve i.e., if the host evolves special resistance against the parasite, the parasite also tends to evolve so that it can neutralize and counteract them to successfully live in or on the same host.
- Many parasites are host- specific i.e., they can only parasite a single host.
- A female mosquito is not a parasite on the human body as it doesn’t spend even a short duration of its lifetime as other parasites do.
- Hyperparasites parasites over the parasites already living in those organisms. For example, bacteriophage parasites over parasite bacteria.
- Brood parasitism: It is a type of parasitism in birds where a parasite bird lays eggs in the nest of the host or the other birds and lets the host incubate them. For example, cuckoo (parasite) lays eggs in the crow’s nest (host).