Every animal’s primal need to reproduce has resulted in an astonishing range of solutions to parental care.
From delivering newborns ready to take on the world, to parents giving up eating to hold eggs in their mouth, species have developed unusual behaviours to ensure the best possible start for their precious offspring.
Humpback whales (Megaptera novaeangliae) give birth to baby giants, tipping the scales at around 1.5 tonnes (1,500kg) – the weight of a fully-grown beluga whale.
"The placenta is huge, like a big white, stinky parachute
They are immediately able to swim but have to quickly develop their skills as in just six weeks they must accompany their mothers on a 3,000 mile (4,828 km) migration to their feeding grounds.
“Size is a function of efficiency for whales, the bigger they are, the easier it is to swim,” explains Rachel Cartwright, leader of The Keiki Kohola Project, which studies humpback calves off the Hawaiian Islands and Alaska.
“As the calves lengthen, then they become more buoyant as their weight to surface area ratio changes.”
Despite their size and great popularity amongst whale watchers, a mystique still surrounds humpback births. Apart from a couple of surface observations, such an event has yet to be reliably documented.
“Over the last 20 years, we have found a couple of traces of placental tissue in the waters around Maui,” Rachel added.
“The placenta is huge, like a big white, stinky parachute. So, some births do happen here, but they may not be the norm.
"Or, it could happen at night, or in the deep. It’s got to be driven by the aim of reducing predation, but remains our big mystery.”
Such secrecy has unfortunately eluded one of the more gruesome animal deliveries, so-called 'skin-care' practised by the Surinam toad (Pipa pipa), filmed for the BBC series Weird Nature, first broadcast in 2002.
It all starts with some energetic mating that helps the fertilised eggs land on the females back. She grows skin around each one, forming a honeycomb structure. The eggs hatch and develop inside these skin pockets over the next four months.
It’s a novel way of ensuring the survival of up to 100 eggs, all of which avoid the dangers of the free-swimming tadpole stage, and offspring triumphantly pop out as fully formed toadlets.
Another freakish birthing behaviour is mouthbrooding, where offspring are incubated in their parent’s mouth.
Many species of cichlids are mouthbrooders – the female lays her eggs and then picks them up in her mouth.
“For most fish, being an egg sucks
The male fertilises them in her mouth, and the eggs stay there. They hatch after about seven days but some dedicated parents continue to carry the fry for another few weeks, forgoing food until the young are released.
In some species childcare duties are undertaken by the female, in others both parents do it and, in a few cases, the male takes on the role.
“For most fish, being an egg sucks,” says Ronald Coleman, Associate Professor of biological sciences at California State University, Sacramento, who filmed the process in his laboratory.
“Many, many fish eggs die from fungus, predation, being swept away and so on. Mouthbrooder eggs have the good life.
“When the fry come out of the parent's mouth, they are large and ready to go and have an incredible survival advantage over non-mouthbrooder kids.”
Returning to births that won’t put you off your dinner, the lined seahorse’s entry into the world represents a complete role reversal.
Male seahorses (Hippocampus erectus) grow special birthing pouches on their stomachs.
The female seahorse lays her eggs in the male’s pouch, then it's all down to him – fertilising and incubating the eggs until he gives birth.
The seahorse's fish family Syngnathidae, which includes pipefish and sea dragons, are the only animals where males actually experience pregnancy.
Scientists have discovered that it has caused significant changes in the mating game for some species, with males becoming the picky ones, selecting larger females and even how many of their offspring survive.
While few births are truly dignified, giraffe calves (Giraffa camelopardalis) face a dramatic introduction to the world as the tallest land-living animal gives birth standing up.
She quite simply drops the baby 1.83m (6ft) to the floor, breaking the umbilical cord in the process.
They are very vulnerable to predation immediately after birth
Remarkably no harm is done and calves are active shortly after.
“Calves can walk within an hour of birth,” says Stephanie Fennessy from the Giraffe Conservation Foundation.
“This is important as they are very vulnerable to predation immediately after birth with approximately 50% of giraffe calves not surviving their first year.”
Calves have to be around 1.83m (6ft) tall at birth in order to reach their mother’s milk. It requires a gestation period of 15 months, but such investment can create a strong bond between mother and calf.
“Giraffe mothers tend to be very protective of their calves and there have been observations of giraffe kicking lion to protect their calves,” Stephanie adds.
Unsurprisingly calves aren't in any rush to leave mum behind and can stay dependent on her for up to 22 months.
Watch Life Story on Thursday 23rd October at 21:00 on BBC One.