Like a Virgin by Prasad, Aarathi (recommended reading txt) 📕

itself, the animals get tangled in commercial fishing nets or are mistakenly caught on hooks by recreational sportsmen. As a result, the shark is now listed by the World Conservation Union as globally vulnerable and as critically endangered in eastern Australian waters; its risk of extinction is high.

Part of the problem is the way in which grey nurse sharks reproduce in the wild. When a female becomes pregnant, dozens of embryos are produced. But at the end of a gestation of nine to twelve months, the lengthy labour expels only two pups, each about one metre (just over three feet) long. The mother then enters a year-long rest before the next pregnancy. This means that the shark’s birth rate is low, and births are few and far between. And it is lucky that the female produces two pups at all, and not just one – because the female grey nurse shark has not one but a pair of separate wombs, so these offspring develop in isolation. And there is a reason for that.

The grey nurse shark is what most people think of when the word ‘shark’ is mentioned, despite the cinematic fame of the great white. In fact, historically, most sharks were labelled the grey nurse – especially if they had taken a bite out of a person. It’s easy to see why – their menacing appearance is compounded by the fact that this is one of the few shark species to display its impressive jaw of jagged teeth all the time. But most attacks attributed to the grey nurse are now considered to have been committed by other animals, and it is believed that they have never actually been involved in a case of an unprovoked attack on a human. But while their savage reputation is unwarranted when it comes to humans, you can see how it might have been earned when you consider exactly how grey nurse foetuses develop in their mothers’ wombs – through cannibalism.

Until they reach a length of about six centimetres (just over two inches), the embryonic grey nurses are nourished by the egg’s store of yolk. When they hatch from the egg, the foetal pups swim into the so-called nurseries inside the mother’s body – what we would call the wombs – but very little nourishment is left there. Luckily, by the time the foetuses grow to about ten centimetres, they have developed a nice set of menacing jaws. To feed themselves, the foetuses begin to eat the remaining egg capsules, containing eggs and younger embryos, and then, once they have consumed all of that, they attack the other foetuses in the womb – their siblings. The first foetuses to hatch will be the largest of the batch, so the baby shark that manages to eat all of its siblings is likely to be the one that was fortunate enough to develop first. This cannibalism does mean, though, that out of the up to eighty embryos at the beginning of the pregnancy, only one victorious pup is left in each womb at the end. As the other foetuses aren’t enough to feed the pup through to delivery, the mother shark nourishes the two remaining pups, safely separated from each other’s jaws in their separate wombs, with a continuous supply of freshly produced eggs. Every grey nurse shark has survived at the expense of dozens of its siblings – and thus no one female can produce more than two pups every two years.

These are not figures that can sustain an endangered species, and that’s how the idea of an artificial womb came about. The idea was suggested, in general terms, by an Australian government minister in charge of fisheries but who was himself a farmer. As such, he was well versed in the manipulation of reproductive strategies, such as IVF, as a way of addressing breeding problems in cattle and other livestock. He challenged scientists to create a similar intervention that might increase grey nurse shark numbers. Nick Otway answered the challenge by looking for a means of pulling those dozens and dozens of shark embryos out of the mother and giving them a fair chance of coming to full term, away from the jaws of their siblings.

To create a successful surrogate for a shark womb, Otway, his research partner Megan Ellis, and their team first needed to figure out what a shark womb is like. What is the chemical composition of the fluids in the womb, and of the eggs that the mother feeds the foetuses? What amount of oxygen exists in the womb, and what is the fluid’s temperature? Are there types of bacteria that should be present, because they exist in the womb’s natural environment and might play some crucial role? What is the consistency of the walls of the womb, and does the mother’s body allow extra nutrients to be supplied through it? Do any or all of these factors change at different stages in the course of a pregnancy? And could scientists invent an artificial fluid to match the womb fluid, or re-create the overall environment?

To test the artificial womb prototype they developed, the scientists turned not to the endangered grey nurse, but instead to the related wobbegong, or carpet shark. The wobbegong is more docile in outward appearance than its cousin: flat, sand-coloured, and patterned, with short catfish-like tentacles surrounding its mouth; it keeps its sharp teeth hidden from view. It’s also smaller and easier to handle than the grey nurse. Internally, the wobbegong is simpler in structure, but there are similarities between the two species. Of special note to the research team, the wobbegong reproduces more frequently than the grey nurse and was in no danger of dying out.

In a surgical procedure, Otway and the team removed six embryos from a wobbegong and placed them in their specially designed tank filled with some