ABSTRACT
In animals, parental care commences from an egg guarding at one end of a spectrum to brooding, paternal gestation (e.g. pipefishes) and matrotrophic viviparity at the other end of it. Brooding allows protection in nest holders (e.g. some fishes) and ventilation in others (e.g. decapod crustaceans) and the delivery of nutritive fluids in ovoviviparous in yet others (e.g. Cladocera: Moina, Polyphemus). The broadcast spawning crustaceans produce 3–20 times more eggs than their respective brooding taxonomic counterparts. This may also hold true for terrestrial animals, albeit the values for each of the three groups may not be as high as in those of aquatic animals. Viviparity involves adaptations for internal fertilization, maternal gestation and parturition. Despite limited species diversity, the incidence of viviparity is reported from almost all phyla indicating the safest mode of completing embryogenesis.
