According to Elton (1965), the animal succession may be best studied in very simple communities.
It can be studied experimentally in the laboratory by making a hay infusion in water and leaving it open to the air for several weeks.
Bacteria are the first organisms to become abundant, since they live upon the decaying vegetable matter.
The various protozoan’s appear, and it is possible to see a whole animal community being gradually built up, as each new species arrives and multiplies and fits into its proper niche. In the hay infusion the bacteria are followed by small ciliate protozoa of the Paramecium type, which subsist upon bacteria and also by absorbing substances in water.
Then there are larger hypotrichous ciliates, which prey upon bacteria and smaller ciliates. Eventually the whole culture may degenerate due to a decrease in food material for the bacteria and therefore for the animals feeding on them. On the other hand green autotrophs, in the form of small algae may arrive and colonise the culture.
These will be able to subsist for a long time, and may change the character of the whole community by providing a different type of food. This is heterotrophic type of succession where R exceeds P (or where P may be ultimately zero), but on the appearance of algae an equilibrium is approached and PIR ratio tends to approach 1.
Succession may also be observed in other cases. The kinds of insects that infest granaries change radically from month to month in regular fashion. Here no climax is reached, however, because the stored grain does not renew itself and does not become available again for further generations of beetles, as the soil nutrients do in the pond, land or forest.
Animals also play an important role in ecological succession in the sea. According to Wilson (1925), who studied succession on bare areas on the seashores, the pioneers were colonial diatoms, which formed the first community. These were followed by a group of colonial hydroids (mostly Obelia), and the latter were then replaced by a sea weed (Ectocarpus), which became dominant species for about four months. Further stages were foreshadowed, and it appeared that the whole would ultimately develop into a climax species of other sea weeds (chiefly kelp).
The interesting thing about this sere is the fact that the second stage in succession is formed by sessile animals, and is sandwiched between two plants stages. The zonation of animals and plants in the intertidal zone in other regions is often an alteration of animal and plant dominance, e.g., Baianus or Mytilus and seaweeds, in the temperate region. On coral island, succession may consist almost entirely of a series of animal zones with only an occasional plant zone formed of calcareous algae.