Postembryonic Development

Postembryonic Development

 

the period in the ontogenesis of multicellular animals that follows the period of embryonic development and usually ends with the onset of sexual maturity and, in most animals, the cessation of growth. Postembryonic development begins after the emergence of the embryo from the egg and embryonic membranes, when the organism becomes capable of active feeding and locomotion. Upon transition to the postembryonic state the organism either immediately possesses the principal pubertal morphological characteristics (direct development) or essentially differs from the pubertal form, in which case the larva that hatches out of the egg must undergo a metamorphosis before it reaches its adult state. Growth continues during the period of postembryonic development and further organogenesis and histogenesis occur. The functions of the developing organism become more complex; establishment of the final proportions of the body is especially characteristic.

In some animals postembryonic development constitutes the greater part of their life span. Among insects, in a number of cicadas the larva lives 17 years, while the pubertal insect lives one summer; the mayfly larva lives to three years, but often in its pubertal form the mayfly lives only one day.

The necessity for defense against enemies and active food procurement are ensured during postembryonic development by a number of adaptations that make the animal self-sufficient, sometimes for its entire life span. With indirect, or larval, development, the animal, having larval organs, is self-sufficient only during the postembryonic period.

A. V. IVANOV

References in periodicals archive ?
It should be noted, however, that developmental deformities of this kind are extremely rare and usually lead to death of the affected individual in the early stages of postembryonic development.
Another related question is how spider eyes are focused during postembryonic development.
Nevertheless, this interpretation will need to be confirmed with evidence from studies of postembryonic development.
The first phase covers the planktonic period of postembryonic development, and the second period represents benthic life.
Postembryonic development of the cranial lateral line canals and neuromasts in zebrafish.
Our goal was to investigate whether and in what way, increasing body size alters spatial vision during the course of postembryonic development, and to what extent this has biological relevance in terms of prey-capture and locomotory behavior.
Although cocoon care and postembryonic development in spiders have been thoroughly studied, spiderling emergence is only known from a few observations, mainly in Araneomorphae (Eason 1964; Engelhard 1964; Fujii 1978; Vannini et al.
Cell death is an essential phenomenon in cell homeostasis and its occurrence during embryonic and postembryonic development has been well documented.
Postembryonic development of Ronderosia bergi (Orthoptera: Acrididae: Melanoplinae) under controlled conditions
A new species of Pimeliaphilus (Acarina: Pterygosomidae) parasitic on scorpions, with discussion of its postembryonic development.