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Perfectly preserved sperm dating back 100 million years has been found, trapped in amber.
The sperm, roughly 50 million years older than the earliest previous fossil record, belonged to an ostracod, a class of small crustacean that has existed for 450 million years. It was found in present-day Myanmar.
Based on the fossil record and the behavior of the modern ostracod, the male used his fifth limb to transfer extraordinarily long but immobile sperm to the female.
The sperm was also huge, about 4.6 times the length of the female’s body.
“This is equivalent to about 7.3 m (23 ft) in a 1.7 m (5.5 ft) human,” said Dr. Renate Matzke-Karasz of the Ludwig Maximilian University in Munich.
Sadly for the two little creatures, they were engulfed in tree resin while in full passion.
This resin was fossilized in amber, preserving not just the lovers but dozens of other ostracods.
Researchers from the Chinese Academy of Sciences were able to use X-rays to obtain high-resolution images of the remarkably well-preserved soft tissues of ostracods.
These images provided direct evidence of the male clasper, the sperm pumps, the hemipenes (they had two penises) as well as the female’s eggs and seminal receptacles (they had two of these as well) that contained the giant sperm.
Fascinatingly, research has revealed that sexual behavior in ostracods, featuring a large number of morphological adaptations, has remained largely unchanged for the past 100 million years.
There are a number of conflicting theories about what the evolutionary value of such a long sperm would be, according to Dr. Matzke-Karasz.
“For example, experiments have shown that in one group, a high degree of competition between males can lead to a longer sperm life, while in another group, a low degree of competition also led to a longer sperm life. sperm, “he added.
Whatever the mechanism, the findings reveal “that reproduction with giant sperm is not an evolutionary extravaganza on the brink of extinction, but a serious long-term advantage to the survival of a species,” concluded Dr. Matzke-Karasz.
