Sunday, March 7, 2010

Another Living Jewel

My last post showed a jewel-like case made by a single-celled amoeba. This one shows the remarkable case made by a marine worm.  We found this little tapered tube, about 5 cm. long, on the sandy beach at Warkworth in Northumberland this afternoon. It was made by a worm called Pectinaria koreni and when the animal inside is alive only the last few millimetres of the narrow end of the tube protrudes above the sand. The worm lives head-down in the sand, drawing in a current of water through the narrow end of the tube.

You can see the dark zone at the narrow end here - that's the bit that normally protrudes above the sand. The tube is made up of hundreds of sand grains and minute shell fragments, selected for smoothness inside and outside the tube and ....

.... neatly fitted together with a degree of precision that a stonemason would envy....


.... and although the tube is only one sand grain thick it's remarkably strong. That's because....

... the worm secretes a form of cement that glues the grains together, like mortar in a wall ......

.... as you can see here at higher magnification.

A pair would make rather fine ear-rings, provided the wearer didn't have any qualms about wearing jewellery made by a worm rather than by a jeweller.

You can see a picture of the worm here.


  1. Thanks Ron and Psi Wavefunction - that's nature for you: the closer you look, the more interesting it gets..

  2. What a magnificent shell! And fantastic photography of it, too. Although, having looked at the worm in your link, I'd say he's best viewed while inside his gorgeous shell. The little whiskers at the end are kind of cute, but naked he's a rather unfortunate-looking soul. Hard to believe he can build that perfect home without opposable thumbs.

  3. It is an amazing piece of work, isn't it Woodswoman? Even with opposable thumbs, a microscope and the patience of Job I couldn't come close to producing something as exquisite!

  4. this is incredible! you really discover the most amazing things...

  5. Hi Zoe,it's a fantastic housebuilding feat for a worm, isn't it?


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