Introduction
Among the most known variants of symbiosis, commensalism plays a cardinal role: we are talking about a relationship established between two living organisms - known as commensals - in which a protagonist of the relationship takes advantage of it, while the other does not benefit from any benefit, nor is it damaged in any way. Many diners belonging to different species peacefully occupy the same place, without damaging the other components: for this reason, commensalism is often referred to as tenure .
Commensalism is a very important form of correlation between different species: just think, for example, of all those organisms that, by nature, are too fragile or weak to face opponents alone fearlessly. Thus, only by finding refuge in organisms of other nature can they take shelter, while not causing damage to the individual that hosts them: a classic example is represented by the birds that find refuge in the hollows of trees.
Diner
The commensal name derives from the English word " commensal " which literally means sharing food, an expression that refers to human relationships; the Anglo-Saxon commensal, derives, in turn, from the Latin term cum-mensal which, translated, refers to a "sharing of the table / of the table", in reference to the sharing of the same food among animals of different species. Originally, the word commensal was used exclusively to describe the use of waste from some animals (or their carcasses) from other species, after the predators had finished their meal.
Classification of commensalism
There are more forms of commensalism:
- Tenancy : an organism uses another to live there. An example is epiphytic plants (like many orchids) that grow on trees, or birds that live in cavities in trees.
- Metabiosis : it is a rather complex form of commensalism, indirect, in which an organism uses what a second organism has originated, following its death.
- Foresi : commensalism is in this case aimed at transporting one animal by another, typical is the commensalism between mite and insects / birds: the mite, lying on bees, butterflies or other animals, is transported from a place to the other, not causing, however, any damage to the guest.
Insights
The boundary between commensalism, tenacity, mutualism and other symbiontic variants is often extremely thin, so much so as to often create confusion between the various terms.
In all likelihood, the commensal organism that lodges in the host (larger) will not come out of it for life, at least not spontaneously: in doing so, the small diner permanently binds his fates to those of the host. In this case we talk about tenure. When the little guest dies, the guest could take advantage of it, feeding on the remains of the partner: here, therefore, that the relationship of initially tenacity turns into a sort of parasitism.
It is also difficult to define with certainty whether the symbiosis between intestinal bacteria and man can be defined as a form of symbiotic mutualism or commensalism.
