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Biology - Living as a Parasite

Living as a Parasite

Many of the pathogens [1] described above can also be called parasites
[2], because they live in or on other living things (the host) to obtain
their nutrients. Other kinds of organisms are parasitic too.

Parasites [3] can be classified in a number of ways. A common one is
according to their relationship with their host.

* ectoparasites [4] live on the surface of their host, e.g. in fur,
feathers and skin, and on roots, stems and leaves

* endoparasites [5] live in some part of the body of the host, e.g. in
gut or muscle, or inside leaves or other plant tissues

The host is usually affected by:

* the parasite's feeding activities - damage to tissues and blockage of
blood vessels, ducts and vascular tissue in plants

* the production of toxins - usually protein products of the parasite's
metabolic activities - resulting in fever, headache, nausea and
interference in the host's metabolic activities

* secondary infection - damaged tissues are exposed to other pathogens

_Advantages_ of living as a parasite are:

* a readily available food supply

* reduced competition

* protection/shelter

A _disadvantage_ is the exclusive dependence on the host. If the host
dies, the parasite dies.

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Links:
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[1] http://alison.com/#
[2] http://alison.com/#
[3] http://alison.com/#
[4] http://alison.com/#
[5] http://alison.com/#