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Plan to nurture test-tube sharks

Inter-embryo cannibalism within the uterus of the grey nurse shark means that very few embryos make it out alive, so why not grow pups in a lab?

Keeping squabbling children apart is a problem that taxes all parents, but for the grey nurse shark it is a little more serious. Its embryos have a nasty habit of eating each other in the uterus.

This intra-uterine cannibalism means that despite starting a pregnancy with up to 40 embryos in her two uteruses, a female shark only gives birth to two pups. This is a real headache for Australian conservationists trying to save the species from extinction.

To allow the embryos to grow in peace, a team at Cronulla Fisheries Centre in New South Wales has built a prototype artificial uterus, in the shape of a 1-metre-long test tube. The embryos will be flushed from their mother and raised in the tanks, filled with a yet-to-be developed artificial uterine fluid.

The team hopes to raise up to 40 shark pups a year.