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80 | IV. Categories of animal associations
§ THE SMALLEST CATEGORY OF A ZOOCOENOSIS:
THE CATENA
From the statement on the structural elements of animal associations, it
follows, naturally, that their formation is gradual, small at initiation and then
expanding as they develop. Where should we look for the smallest units of
a zoocoenosis?
Given that the most important energy source is the plant cover, the simplest
zoocoenoses should be sought here, at the meeting point of animals directly
feeding on plants, and of zoophagous organisms. The more specialised a
plant-transforming population is for its energy source, the more restricted
will be the zoocoenosis forming around it, both in space and in its relation
to energy sources.
This is the simplest unit of an association, the smallest unit ofa zoocoenosis,
the catena. A monophagous corrumpent, sustinent or intercalary population
belongs to a catena, and its existentially dependent obstant, and possibly
waste-consuming intercalary populations follow. The catena is, therefore, a
trophic chain‘, in which the subsequent trophic levels are represented by the
appropriate structural elements.
One should not view a catena through an idiobiological lens, and be baffled
that the same species may be present in various catenae; this view considers
the species, but a zoocoenosis can only be viewed through a community lens.
Looking at the question with this approach, it becomes clear that an obstant
population living in a given catena (even if its species is polyphagous) is really
existing in this catena - this trophic chain - and it is not possible that it can
be present at the same time in any other place. The circumstance that other
populations belonging to the same species live in other catenae means nothing
more than that it will appear in the species combination of those catenae as
well. The same occurs when an episitic semaphoront, during its hunting trips,
will take prey from several catenae; the moment when it effectively entered
that catena, it became its full member.
This view is not only more correct coenologically, but is also of theoretical
importance, because the various populations of the same species, when they
are active in several catenae, form coenological links between these small
zoocoenological categories. It is certain that several parasitic or episitic obstant
elements that depend on several hosts can only remain in the zoocoenosis
if these hosts are present there. These cannot be members of the same catena
and, due to their intermediary host needs, can only fit into catena A if catenae
Band C are also present. The relative obscurity of obstants, compared to the
+ For these links, we use this term instead of the food chain, which has a production biological “nuance’,
emphasising the distance kept from any production-biological approach or influence. By food chain
we mean the path through which the energy-binding organic material progresses through the animal
elements, while a trophic chain is the mutual dependence of populations that are forced into a
zoocoenosis because of their trophic dependence. We believe such a sharp distinction is useful.