Those are parasites
A living organism
parasite
parasite
An organism is another word for a living thing.
A host...
A parasite is an organism that lives in or on another organism (host) and benefits at the expense of the host's health or resources. Parasites can cause harm to their hosts by causing disease or feeding on their tissues.
Organism is another term used to refer to a living thing.
Parasites are the name given to organisms that live on or in another organism. Example: fleas, ticks, and bacteria.
This is known as a symbiotic relationship, where one organism lives in or on another organism. The organism living within is called an endosymbiont (e.g., bacteria within the human gut), while the organism living on the surface is an ectosymbiont (e.g., barnacles on a whale).
Any living thing can become extinct.Extinct means that this organism no longer exists. This can happen to any type of living organism(or non-living organism, if you are talking about viruses). if you are refering to a human being the person has to die before that person is extinct
Organisms can be grouped as free-living or parasitic. A parasite is an organism which lives in or on another organism, from which it obtains its food. Since humans do not do this they are not parasitic, and so must be free-living.
It's called a parasitic relationship.