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Chickens
are birds.
The female is a hen.
The male is a rooster.
Baby chickens are called chicks. They hatch out of fertilised (say fur-till-eye-zd) eggs laid by the hen. Eggs are fertilised by the rooster. During mating, sperm from the rooster leaves his body through an opening called a cloaca and passes into the hen through her cloaca.
The sperm fertilises soft eggs inside the hen's body, one at a time. The fertilised eggs travel towards her cloaca and, on the way, the white is added to the yolk and a soft shell forms around the egg to protect it. The nearer the egg gets to the cloaca, the bigger it grows. A fertilised egg is laid every 24 hours after fertilisation.
The hen incubates the eggs for 21 days by keeping them warm with her body. Inside each egg is an embryo (say em-bree-oh) that is growing into a chick. The hen turns the eggs so that the developing embryos do not stick to the shell.
The chicks peck holes around the shell
and push themselves out of the eggs. Their feathers are wet but
they soon dry.
Chicks are able to run about and feed themselves shortly after hatching. A young hen is able to lay eggs when she is 6 months old.
The chicken eggs we eat are not fertilised eggs: there is no embryo inside. With no rooster around to fertilise her eggs, a hen still lays an egg every day.
Go
here for a kidcyber activity page: constructing the life cycle of a chicken
Go here to the Museum of Science in Chicago to see a video of a chick hatching.
http://www.msichicago.org/exhibit/chick/chick.html
Go here for detailed information, photographs and diagrams of the 21 day development of chicks inside the egg. http://chickscope.beckman.uiuc.edu/explore/embryology/
Remember: Always
acknowledge where you find information
If you use any of the information on this page, acknowledge this source in your bibliography like this:
Life cycles:
Chickens (2003). [Online], Available: www.kidcyber.com.au
updated July 2006