Page last updated at 18:52 GMT, Thursday, 18 June 2009 19:52 UK

Huge sperm of ancient crustaceans

Ostracod sperm (R Matzke-Karas)
The sperm can reach lengths 10 times that of the ostracods

A new method for analysing the interior of fossils has shown that millimetre-long mussel-like crustaceans called ostracods used giant sperm to mate.

Sperm of modern ostracods can reach 10 times their body length.

The technique, known as holotomography, imaged the large sperm pumps and seminal receptacles of well-preserved ostracod fossils found in Brazil.

The results, published in Science, show ostracods had already evolved the giant sperm 100 million years ago.

The samples came from the Santana Formation, which has already yielded a wealth of perfectly preserved fossils, particularly of fish.

Because they are scavengers, ostracods were also found in abundance near some of the fish, with their soft internal organs equally well preserved.

New light

Renate Matzke-Karasz of the Ludwig Maximilians University in Germany took Harbinia micropapillosa ostracod fossils, part of the collection of the Natural History Museum in London, to the European Synchrotron Radiation Facility in France.

There, light from accelerated particle beams was used to image the interiors of the fossils, yielding a detailed picture of their inner structure.

What the team found was that the sexual organs of the fossils were remarkably similar to those of modern ostracods.

Ostracod fossil (NHM)
The soft internal organs can be seen between halves of the shell

Both males and females have fully separate pairs of organs. The males have two sperm pumps, or Zenker organs, and the females have two vaginas and large seminal receptacles, separated by a lengthy duct that seems optimised to accommodate the sperm.

"It was very surprising that these structures were so similar to organs we know from modern ones," Dr Matzke-Karasz told BBC News.

"Now we know that it happened at least 100 million years ago - it developed quite early in the freshwater ostracods."

Ostracods are not the only animals that use giant sperm as a mating strategy - it has also been seen in the fruit fly Drosophila. However, because it costs a lot of energy to produce long sperm, it is still unclear to biologists why the strategy arises.

For Dr Matzke-Karasz, the results open a new avenue of research for palaeontologists.

"This holotomography is so helpful; it could bring out much, much more of fossils which are all over the world in museums, buried in the collections," she said.



Print Sponsor


SEE ALSO
Ancient fossil penis discovered
05 Dec 03 |  Science & Environment
Fossils date Dry Valleys' origin
23 Jul 08 |  Science & Environment
Battle of the sexes 'prehistoric style'
13 Sep 02 |  Leicester 2002

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites


FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

BBC navigation

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific