Egg incubation is the process by which an
Multiple and various factors are vital to the incubation of various species of animal. In many species of reptile for example, no fixed temperature is necessary, but the actual temperature
A wide range of incubation habits is displayed among birds. In
In the species that incubate, the work is divided differently between the sexes. Possibly the most common pattern is that the female does all the incubation, as in the Atlantic canary and the Indian robin, or most of it, as is typical of falcons. In some species, such as the whooping crane, the male and the female take turns incubating the egg. In others, such as the cassowaries, only the male incubates. The male mountain plover incubates the female's first clutch, but if she lays a second, she incubates it herself. In hoatzins, some birds (mostly males) help their parents incubate later broods.
The incubation period, the time from the start of uninterrupted incubation to the emergence of the young, varies from 11 days (some small
Embryo development remains suspended until the onset of incubation. The freshly laid eggs of domestic fowl, ostrich, and several other species can be stored for about two weeks when maintained under 5 °C. Extended periods of suspension have been observed in some marine birds. Some species begin incubation with the first egg, causing the young to hatch at different times; others begin after laying the second egg, so that the third chick will be smaller and more vulnerable to food shortages. Some start to incubate after the last egg of the clutch, causing the young to hatch simultaneously.
Incubation periods for birds:
|Bird||Incubation Period (days)|
|Duck||28, Muscovy duck 35|
Very few mammals lay eggs. In perhaps the best known example, the platypus, the eggs develop in utero for about 28 days, with only about 10 days of external incubation (in contrast to a chicken egg, which spends about one day in tract and 21 days externally). After laying her eggs, the female curls around them. The incubation period is divided into three phases. In the first phase, the embryo has no functional organs and relies on the yolk sac for sustenance. The yolk is absorbed by the developing young. During the second phase, the digits develop. In the last phase, the egg tooth appears. The only other egg-laying mammal is the echidna. New science research has been found that eggshells have a nanostructure that has inner and outer layers. The structure of this shell contains a protein known as osteopontin which is also found in tooth and bone. What researchers found was that the inner layers of the shell were thinner than the outer shells. This is because in the process of the egg being incubated the chicken embryos are taking the protein from the shell making the chicks skeleton stronger.
Methods of incubation vary widely among the many different kinds of reptiles.
Various species of sea turtles bury their eggs on beaches under a layer of sand that provides both protection from predators and a constant temperature for the nest.
Snakes may lay eggs in communal burrows, where a large number of adults combine to keep the eggs warm. Some species coil their torsos around the eggs to provide heat for incubation.
Incubation by other vertebrates
Fish generally do not incubate their eggs. However, some species
Some amphibians brood their eggs. The female salamander
Incubation by invertebrates
Brooding occurs in some invertebrates when the fertilised eggs are retained inside or on the surface of the parent, usually the mother. This happens in some cnidarians (sea anemones and corals), a few chitons, some gastropod molluscs, some cephalopods, some bivalve molluscs, many arthropods, some entoproctans, some brachiopods, some bryozoans, and some starfish.
- De Marchi, G., Chiozzi, G., Fasola, M. 2008 Solar incubation cuts down parental care in a burrow nesting tropical shorebird, the crab plover Dromas ardeola. Journal of Avian Biology 39 (5):484–486
- Warham, J. (1990) The Petrels – Their Ecology and Breeding Systems London:Academic Press.
- Pettingill, OS Jr. Ornithology in Laboratory and field (4 ed.). Burgess Publishing Company. pp. 357–360.
- 'Eggless' chick laid by hen in Sri Lanka, BBC News Online, 19 April 2012, retrieved 28 April 2012
- Divoky, G.J.; Harter, B.B. (2010). "Supernormal delay in hatching, embryo cold tolerance, and egg-fostering in the Black Guillemot Cepphus grylle" (PDF). Marine Ornithology. 38: 7–10. Archived from the original (PDF) on 21 March 2012.
- Erica Cromer (14 April 2004). "Monotreme Reproductive Biology and Behavior". Iowa State University. Archived from the original on 13 March 2009. Retrieved 18 June 2009.
- "Ockhams Razor". The Puzzling Platypus. Archived from the original on 4 April 2005. Retrieved 2 December 2006.
- OCLC 51922852.
- Jordan, Rick; Mark Moore (2015). A Guide to ... Macaws as Pet & Aviary Birds. Burleigh, QLD: ABK Publications. OCLC 910654910.
- Incubation periods in table from PennState Extension