Size Does Matter : Shots - Health News Big sperm sometimes comes in microscopic packages

Size Does Matter

This tiny mussel shrimp's extinct cousin showed the ladies love with his giant sperm /Renate Matzke-Karasz hide caption

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/Renate Matzke-Karasz

Guys do anything to get the girl. It was the same 100 million years ago.

Some of the hottest studs around during the Cretaceous Period were tiny creatures a bit like mussels called ostracodes. And even though they were only a few millimeters in size, researchers have just discovered that their sperm cells were gigantic - up to ten times as big as the crustaceans themselves.

To peek at what this guy's machinery looked like in a short 3-D movie, click here.

It took some pretty high-tech voyeurism to detect the ostracodes' outsized dating device. Renate Matzke-Karasz of the Ludwig Maximilians University in Germany and his colleagues tell all in Science this week. They took some particularly well preserved Brazilian ostracode fossils to the European Synchotron Radiation Facility in Grenoble, France.

There, beams from a particle accelerator enabled Matzke-Karasz and his colleagues to peer deep into the most secret parts of three male and two female microfossils.

The powerful new technique - known as holotomography - produced precise, three-dimensional images of a humungous reproductive apparatus that could only mean one thing: Whopper sperm. The images even showed the moment of insemination frozen in time.

"The fossil females must have mated shortly before their entombment in the sediment," says Radka Symonova of Charles University in Prague.

What a way to go!