The swamp wallaby is the only mammal that is permanently pregnant throughout its life according to new research about the reproductive habits of marsupials. Unlike humans, kangaroos and wallabies have two uteri.
The Patient Pachyderm
Elephants are the largest land mammals in the world, so it's perhaps not surprising that they have the longest pregnancy of any living mammal: African elephants are pregnant for an average of 22 months, whilst for Asian elephants it's 18 to 22 months.
Black Alpine Salamanders
They typically bear two fully developed young. This salamander's life expectancy has been estimated to last from 10 to even 20 years.
The duration of this period varies between species. The gestation period for a cow is about nine months long. A newborn calf's size can vary among breeds, but a typical calf typically weighs 25 to 45 kg (55 to 99 lb).
The swamp wallaby is the only mammal that is permanently pregnant throughout its life according to new research about the reproductive habits of marsupials. Unlike humans, kangaroos and wallabies have two uteri. The new embryo formed at the end of pregnancy develops in the second, 'unused' uterus.
Most animals that procreate through parthenogenesis are small invertebrates such as bees, wasps, ants, and aphids, which can alternate between sexual and asexual reproduction. Parthenogenesis has been observed in more than 80 vertebrate species, about half of which are fish or lizards.
A pregnant 10-year-old would face significant and potentially life-threatening medical risks in carrying a pregnancy to term — and harrowingly, children even younger than age 10 can become pregnant.
Shark pregnancy
Sharks typically give birth after 11–12 months of pregnancy, but some, such as the frilled shark, are pregnant for more than three years. In some sharks, a placenta develops during pregnancy.
– Decuplets: a combination of 10 of a kind. In this case, babies! A South African woman has reportedly given birth to 10 babies at once, besting a world record set just last month.
Ethical considerations preclude definitive research on the subject, but it's safe to say that human DNA has become so different from that of other animals that interbreeding would likely be impossible.
Gestation in lions is about 110 days and mean litter size is 2.3 (Schaller 1972). Females cease lactation when their cubs are 5-8 mo old (Schaller 1972), but do not resume sexual activity until their cubs are about 18 mo old (Bertram 1975; Packer and Pusey 1983).
James Elgin Gill was born in Ottawa, Ontario, on May 20, 1987, around 128 days early or 21 weeks gestation. He set a record when he was born for the world's most premature baby. 20 James was born so early that he was expected to die at birth or—if he survived—to have multiple and severe handicaps.
Two babies are twins and three are triplets.
According to Guinness World Records, the heaviest baby on record was born in Aversa, Italy, in 1955. That baby boy was born weighing 22 pounds 8 ounces.
CASABLANCA, Morocco -- A woman who broke a world record for giving birth to nine babies at the same time said she feels very happy three months after the delivery -- and hasn't ruled out having more children. To say Halima Cisse has her hands full is a bit of an understatement.
While carrying a baby for nine months may seem like long enough for some human mothers, spare a thought for giraffes who have gestation periods of 15 months!
The female deposits eggs into the male's pouch after a mating dance and pregnancy lasts about 30 days. While inside the pouch, the male supplies nutrients to his developing embryos, before giving birth to up to 1,000 babies.
These small leathery pouches are the cast-off egg capsules of some sharks and their kin. Most fish release their eggs and sperm into the ocean, leaving survival of their offspring to chance.
Boys are able to get a girl pregnant when they begin to produce sperm in their semen. This generally begins when they start puberty, which can be from ages 11 to 14.
Valentina Vassilyev and her husband Feodor Vassilyev are alleged to hold the record for the most children a couple has produced. She gave birth to a total of 69 children – sixteen pairs of twins, seven sets of triplets and four sets of quadruplets – between 1725 and 1765, a total of 27 births.
For example, the great majority of tunicates, pulmonate molluscs, opisthobranch, earthworms, and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites.
Many species of fish, like the kobudai, are known as “sequential hermaphrodites”: they can switch sex permanently at a specific point in their lives. The majority of “sequential hermaphrodites” are known as “protogynous” (Greek for “female first”): they switch from female to male.
Of the 4,000 or so species of mammals, only a handful of animals have ever been thought to mate for life. This short list of animals includes among others: gibbon apes, wolves, coyotes, barn owls, bald eagles, gorillas and barn swallows.
Monoamniotic-monochorionic Twins
This is the rarest type of twin, and it means a riskier pregnancy as the babies can get tangled in their own umbilical cords.