How to make an artificial shark uterus

So, apparently some Australian scientists are attempting to create artificial shark uteruses — so that they can prevent fetal sharks from eating each other in the womb.

Yes, you read that correctly. Here’s the deal: The average female grey nurse shark begins her pregnancy with about 40 embryos in her two uteruses. But it takes a year for the baby sharks to gestate, and by the time they’re ready to be born, there are only two left — one in each uterus. Why? Because by four months they’ve developed a full set of teeth, and the strongest begin cannibalizing the weaker ones. Ay yi yi. I’d heard of wild dingos getting into deathmatches right after being born, but this takes the whole red-in-tooth-and-claw stuff up to the next level.

Anyway, the grey nurse shark population is apparently critically endangered, and since they’re the top predators in the oceanic food chain, the ecosystem could be unpredictably unbalanced if they all vanish. So the scientists are trying to develop an artificial shark uterus so they can capture a pregnant female, flush out the embryos, and raise them independently so they can all be born.

Of course, as Slate wondered, maybe this attempt to tinker with Mother Nature is doomed to failure. Maybe the embryo sharks need to feed on one another to survive long enough to be born; and maybe the pre-birth contest serves to winnow out sharks that wouldn’t prosper in the wild anyway. Scientists aren’t sure, as an AFP story notes:

No accepted explanation has been established for why the grey nurse sharks take sibling rivalry to such extreme lengths. “It would seem logical that the intra-uterine cannibalism does confer some sort of evolutionary advantage, somewhat similar to the survival of the fittest, but it may be the luck of the draw because even the biggest could be attacked,” Otway said.

Well, that’s gotta be a conversation-stopper at cocktail parties. “So, what do you do for a living?” “Oh, I design artificial shark uteruses to prevent inter-uterine embryo cannibalism.”

(Thanks to Franco for this one!)

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