Websailor's Wacky Wildlife World
Created | Updated Dec 3, 2008
A quirky look at wildlife. To be taken with a pinch of
salt, but with more than a grain of truth!
A Nine Month Miracle
One of the most awe inspiring events to witness, or be part of, is the birth of a baby. From one simple act of love, nine months later comes the greatest gift to mankind, a new screaming bundle of life. More than one life in some cases!
The time from conception to birth in humans is approximately 266 days. The progress of a human baby during those nine months or so is amazing. A human being is such a complex animal (that's all we are after all) that it takes many years to become fully grown. No nine day wonder this creature. Humans are the only mammals whose brains keep growing long after birth. This is called 'secondary altriciality'.
Yet the birth of other mammals is equally fascinating. Watching other animals, all with different gestation periods (the time from conception to birth), it is impossible not to marvel at nature. Whether you believe in creation or evolution, it is still a cause for celebration.
Other primates such as the chimpanzee, gorilla and orang-utan have a pregnancy of similar length to humans, give or take a few days. It has been said that the length of gestation in mammals is largely determined by the size of the animal, but I think this is only a guide as many respond to local conditions at the time.
The elephant is the largest land mammal with a pregnancy of some 645 days in the case of the Asian elephant and some 640-760 days with African elephants, somewhere around 22 months. The calves are still dependent on mother, much as a human youngster, until a teenager.
The rhinoceros takes 480 days, and a giraffe 425, and both offspring are expected to be up and running, like the elephant calf, in a matter of hours, if not less. Watching the crashing of a giraffe calf to the floor from a great height can be quite disconcerting, but it appears to come to no harm. Camels also give birth in this way, from a standing start, after 13 months.
Watching a baby elephant with wobbly legs and floppy trunk, or a gangly giraffe tottering on spindly legs is a very emotional experience as we marvel at their ability to adapt to this hostile world in a matter of hours. A hippopotamus, or river horse on the other hand gives birth after eight months, sometimes under water, like whales.
The largest mammal of all, the Blue Whale, weighing in at anything up to 300,000 lb (136,400 kg) has a gestation period of just 10-11 months, and the calves are independent at about six to eight months once weaned.
Both elephants and the blue whale have a similar lifespan to that of humans (with luck and a fair wind!), some 70 to 90 years.
Leaving aside mammals for a moment, the creature with the longest gestation period of all is the Alpine black salamander, a viviparous amphibian found in the Swiss Alps. At an altitude of over 4,600ft it takes around 38 months after which it produces two fully formed young. Well, would you want to arrive in thin, freezing air without all your accoutrements?
The shortest gestation period for mammals on record (average) is 12 to 13 days, this being in marsupials who finish their development in a pouch – the American (Virginian) opossum, the eastern native cat of Australia (Dasyurus viverrinus), the large short-nosed bandicoot and the water opossum. Incidentally, the eastern native cat, or quoll, looks nothing like a cat! It might interest members of h2g2 to note that the kangaroo, also a marsupial, develops over 42 days!
The grey kangaroo 'joey' is born after a gestation period of about four to five weeks, leaving the birth canal head first, to grab its mothers fur with its front feet. It climbs in to the pouch and grabs on to one of her four teats. This gymnastic feat is conducted at a size of 2.5cm while weighing just 1g. Wow! It stays in the pouch for at least 300 days, suckling for a further six months after leaving the pouch, which it treats as a mobile hotel, jumping in and out at will.
Our favourite pets mostly have short pregnancies, like the hamster at about 17 days, and the mouse at 19 days. Rabbits take about 33 days, a little too often some may think. It is interesting to note that the domestic dog produces after some two months, similar to a wolf (64 days).
The domestic cat has a pregnancy of about 61 days also, but wild cats like the lion (108), leopard (94) Bengal tiger (95-109) and Siberian tiger (93-112) are longer because of their size. Perhaps also the need for the right food supplies has to be considered.
Horses and zebras have a similar timescale of 336 days and 365 days respectively. Donkeys range from ten and a half months to just over 14 months, roughly the same as horses.
It is interesting to note that both badgers and giant pandas have a different method of producing young. Badgers can breed all year round employing 'delayed implantation', which means they can control the timing of the birth until conditions are best for producing cubs, usually in the spring. After as much as ten months the fertilized eggs are implanted in the uterine wall, and the actual gestation period of about seven or eight weeks begins. It has been known for a sow to hang on to her offspring for as much as 18 months, when conditions were not right.
The giant panda also exploits delayed implantation, with the fertilised egg suspended for varying periods, so the actual gestation period cannot be gauged with any accuracy. It is known that from actual mating until birth can take as long as 95 to 160 days. Again, like the badger, the mother waits until conditions are right in terms of food supplies and temperature.
A strange animal called the Cape pangolin has a gestation period of some 135 days and the single baby suckles, living in a den for about a month, before being moved around for safety, with mother, often riding on the mother’s scaly back.
Back to more mundane animals, with whom we have a closer connection, like the domestic cow. This animal has a pregnancy much closer to nine months than humans: 279 to 292 days, while goats need 150 days, sheep 148 and domestic pigs 114 days.
Then of course we have fish, birds, reptiles and insects, and that’s a whole different ball game. However, I can't resist mentioning the very strange behaviour of the seahorse. This strange ethereal creature needs clean water, with good nutrients and the right temperature before mating. After a complicated courtship 'dance', the female will lay her eggs in the male's breeding pouch. Once the eggs are settled in the pouch closes and they remain there until the birth, which can be as little as 15 days later for the Dwarf seahorse and longer for larger species.
So, as we celebrate another miracle—the birth of another edition of The Post, in this its ninth year (with all the usual labour pains and frustrations), can I say thank you to all involved and may I wish you many, many more.
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