summary 5 surviving in ecosystems

Mutualism is the way two organisms interact where each individual derives a fitness benefit (i.e. increased survivorship). Similar interactions within a species are known ascooperation . It can be contrasted with interspecific competition , in which each species experiences reduced fitness, and exploitation , or parasitism, in which one species benefits at the expense of the other. Mutualism and symbiosis are sometimes used as if they are synonymous, but this is strictly incorrect: symbiosis is a broad category, defined to include relationships which are mutualistic, parasitism or commensalism.
parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the host. Traditionally parasite referred to organisms with lifestages that went beyond one host (e.g. Taenia solium), which are now called macroparasites (typically protozoa and helminths). Parasites can now also refer to microparasites, which are typically smaller, such as viruses and bacteria and can be directly transmitted between hosts of one species. Parasites are generally much smaller than their host, show a high degree of specialization for their mode of life, and reproduce at a faster rate than their hosts. Classic examples of parasitism incjkplude interactions between vertebrate hosts and diverse animals such as tapeworms, flukes, the Plasmodium species, and fleas. Parasitism is differentiated from parasitoidism, a relationship in which the host is always killed by the parasite such as moths, butterflies, ants, flies and others..
commensalism
 commensalism is a class of relationship between two organisms where one organism benefits but the other is unaffected. There are three other types of association: mutualism (where both organisms benefit), competition (where both organisms are harmed), and parasitism (one organism benefits and the other one is harmed)..