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English: Figure 4. The major mechanisms of innate memory in invertebrates. The two major phenomena underlying the capacity of invertebrates to mount a more effective defensive response after priming, speaking sensu stricto, are the recall response (upper part) and the immune shift (lower part). As general mechanism (center part), priming is expected to induce epigenetic reprogramming that, upon challenge, determines improved clearance of parasites and enhanced survival. At the level of the whole organism (left part), memory can encompass mechanisms leading to an increase in the number of immune cells at the site or reaction (haematopoiesis, mitosis, haemocytosis), and also the capacity of transferring resistance across generations. At the cellular level (right part) it is also possible to observe increased effector functions in individual cells (e.g., an increased phagocytic rate vs. phagocytic index). Mechanisms that are observed both at the global and cellular levels (lower part) encompass the increased production of soluble immune mediators and the shift of immune response from an initial protective reaction (e.g., phagocytosis) to a more effective mechanism (encapsulation).