ABSTRACT
The fertilized eggs, collectively called fecundity, are a decisively important factor in recruitment and sustenance of population size. Fecundity ranges from one egg in the microscopic placozoan Trichoplax adharens to one billion eggs in the long living snookfish Centropomus indecinalis. Aside from it, fecundity is also complicated by the existence of semelparity and iteroparity, brooding and viviparity, nurse eggs and adelphophagy and poecilogony, i.e. simultaneous release of lecithotrophic larger and planktotrophic small eggs in a few polychaetes and gastropods. Potential Fecundity (PF) is the maximum number of oocytes commencing to differentiate and develop. Due to a number of factors like food supply, only a fraction of the PF is realized. Contrastingly, penaeid eggs are hydrated after spawning; in them, with increasing body size, fecundity increases, as expected but egg size decreases. In parasitic species from different phyla, an assured food supply dramatically increases fecundity including in eutelic nematodes.
