Pregnancy - a significant time in life of animals. Full incubation and timely childbirth are the key to healthy and competitive posterity.
Instruction
1. Pregnancy of mammals is subdivided into several stages: fertilization – merge of men's sperm to a female ovum, penetration of the impregnated cage into a muscular bag – a uterus, development of a fruit. A logical conclusion of pregnancy is childbirth.
2. Depending on quantity of an issue, distinguish one-fetal and polycarpous pregnancies. Here indicators fluctuate from a look to a look. So, on average at predators 2-20 cubs, at hoofed animals 1-2, at rodents 2-10, at wing-handed animals 1-2 cubs in a dung are born.
3. Pregnancy duration in most cases depends on the animal size. The huge elephant bears a fruit 20-22 months, a rhinoceros – 15, a hippopotamus – 8, a cow – 9, a horse – 11, a lion – 3.5, a dog – 2. Pregnancy of smaller animal is estimated in the days: a hedgehog and a polecat – 40, a mouse – 21, columns – 28. But this regularity has exceptions. At a marten, an ermine and a sable time from the moment of conception before childbirth is 9-10 months. Such term is explained by the fact that the impregnated ovum develops not right after conception, and waits favorable conditions.
4. At marsupials very short term of incubation because the fruit is not connected with a maternal organism, and receives food from a zheltochny bubble. The appeared cub is similar to an embryo more: pink transparent skin, lack of indumentum. It continues the development in a vyvodkovy bag, eating mother's milk. The cub of a kangaroo will see off in a womb of only 35 days, and lives in a bag up to eight months.
5. Childbirth at animals lasts till several o'clock. After the birth the female cleans from slime of companies and a nostril of a cub, licks it. How developed and independent the cub will be born depends on the habitat.
6. The longest pregnancy - at a black Alpine salamander (31 months), the shortest – at a North American opossum (8 days). The most developed cubs are born at elephants and hoofed animals, the most helpless - at marsupials. The biggest broods - at rodents and predators (to 20), the smallest – at elephants and whales (1).
7. The elephant calf is born with dairy five-centimetric tusks. Kitenok is born up to 800 kg and up to 5.5 meters long, daily drinks up to 380 liters of milk. Directly after the birth the female takes out it on a surface for an independent breath. Normal pregnancy of pigs lasts 3 days, 3 weeks and 3 months, childbirth – till 6 o'clock. Blind cubs of marsupials in minutes reach mammary glands of a female. At cats, dogs, foxes and wolves, thanks to the general ancestors, the equal term of pregnancy (2 months).