The most important property of living organisms – ability to reproduction and reproduction. The majority of animals in this process has nothing special, they have genitalia, breeding sexually: the spermatozoon of a male gets into an ovum of a female, impregnating it, the female becomes pregnant and gives birth to cubs.
High-organized animals generally have only one way of reproduction which is carried out with the participation of gametes.
There is a number of animals who have no external sexual characters (almost at all birds) and also the hermaphrodites containing and male, and female gonads.
Features of reproduction of some animals
In population of silver crucians there are some females as this look is same-sex. Other small fishes which spermatozoa give development to ova of females of silver crucians impregnate females. Some low-organized animals are capable to reproduction and without fertilization, at them sexual reproduction exists in the same row with development without fertilization. For example, if eggs of a bee are not impregnated, from them drones turn out. Similar occurs also at the lizards living in rocks.
The kangaroo is the only animal at whom the huge difference in sizes between mother and a cub is observed. Kengurenok is born of the size of a pea.
Pigs become mature approximately by eight months, however to give healthy posterity and fruitfully they are capable to breed only aged, years are more senior. Females have a regular sexual cycle which is followed by excitement, techky, sexual hunting, an ovulation and braking. If after fertilization the pregnancy does not occur, the cycle is repeated again. The birth of little infant rats is very interesting. In two weeks of observations it is possible to see how the given rise blind, deaf, bald creation promptly turns into a fluffy brisk small animal. Techka at rats occurs everyone four - five days, except for pregnancy, and to birth they are capable at the age of five weeks. Only strong cold or a heat can slow down rapid process of reproduction at these animals.
Ways of fertilizationThe planet is full a variety of the living beings inhabiting the land, the sky, the sea, and all of them breed differently. At some animals the fertilization is preceded by the long period of courting and the choice of partners. Some choose to themselves couple on for the rest of the life. There are various ways of reproduction of animals, but they are more often it do like people. For example, dogs have sex as people, only only two times a year when at females there comes the techka. Many observed "dog weddings" when for a female the herd of dogs runs, and she copulates with them in turn, and then gives birth to puppies. Similar process of "courtings" happens at cats: cats fight, run for a female, here one cat for time can only impregnate her. However at repeated pairing with other male, the cat can give rise from both at once. Reproduction and ways of fertilization at artiodactyl (horses, cows) happens similarly.