Broken coral embryos become clone army

Reef-building corals turn a turbulent upbringing into an advantage. Although currents break up fragile coral embryos, each fragment can develop into a normal adult.

On the Great Barrier Reef, most corals take part in mass spawning. A few nights after the November full moon, they simultaneously release sperm and eggs, which join in the open water. The resulting embryos drift for hours before settling onto rocks and developing into adult corals.

But the free-floating embryos are vulnerable because ? unlike most organisms ? they don't have a protective outer membrane, says Andrew Negri of the Australian Institute of Marine Science in Townsville, Queensland. Negri found that 45 per cent of Acropora millepora embryos break apart in gentle turbulence.

Although that sounds bad, Negri's studies suggest otherwise. Whether shattered into small clumps of cells, or even single cells, the embryo fragments survived and developed as normal. The resulting larvae were smaller than usual, but they successfully settled and transformed into corals.

Negri says the embryos of four coral families are known to fragment in a similar way, so the ability is probably a common feature of many corals. "Given that corals have existed for hundreds of millions of years, the lack of a protective embryonic membrane is probably no accident," he says.

Being able to make multiple offspring from a single fertilised egg would be a boon for corals, says Rachel Jones of the Zoological Society of London. Making eggs takes a lot of energy, and each has a vanishingly small chance of survival. "It's all about maximising numbers," she says.

Journal reference: Science, DOI: 10.1126/science.1216055

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

Have your say

Only subscribers may leave comments on this article. Please log in.

Only personal subscribers may leave comments on this article

Subscribe now to comment.

All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.

If you are having a technical problem posting a comment, please contact technical support.

Source: http://feeds.newscientist.com/c/749/f/10897/s/1d12edf3/l/0L0Snewscientist0N0Carticle0Cdn215330Ebroken0Ecoral0Eembryos0Ebecome0Eclone0Earmy0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fonline0Enews/story01.htm

x factor judges x factor judges raiders news raiders news ice cream sandwich android ice cream sandwich android harry belafonte