'Oldest Ever' Enormous Sperm Found Locked in a Piece of Amber That Solidified From 100 Million Years, Stuns Scientists
In 2020, scientists announced the discovery of what they believed to be the oldest sperm in the world. The sperm in question was of an ostracod and was adjudged to be around 100 million years old, Live Science reported. The sample predates the next oldest animal sperm available with experts by around 50 million years. Findings regarding the sperm have been published in Proceedings of the Royal Academy B.
Researchers were ecstatic by the discovery because finding specimens of fossilized sperm is rare. The sperm was nestled inside the reproductive tract of an ancient female crustacean encased within an amber in Myanmar.
On examination, researchers found that the female crustacean belonged to an unknown species. Later that species was named Myanmarcypris hui. The sperm's age was found by dating the amber. Examination unveiled that amber is from the Cretaceous period.
The female crustacean was analyzed using 3D X-ray reconstructive technology. It was during the scans that experts found ripe sperm inside the sperm receptacles of the female's body. Researchers believe that the female was waiting for her eggs to mature, and then would have fertilized them with the stored sperm. The plan could not materialize because she possibly got trapped in the sticky tree resin which later hardened to become the amber.
"This female must have mated shortly before being encased in the resin," He Wang, from the Chinese Academy of Sciences in Nanjing added, CNN reported.
Ostracods more commonly known as 'seed shrimp' are very minuscule (a few tenths of an inch). The researchers were taken aback when they first uncovered the size of their sperms. The longest sperm ever produced by ostracod was 0.46 inches (11.8 millimeters). The 100-million-year-old sperm uncovered by scientists is also 'giant' by size and measured 200 micrometers long.
The feature of oversized sperms was surprising for researchers because most male animals typically produce small sperms in their reproduction activities. The unique behavior in Ostracods could be some form of adaptation undertaken by the beings during their evolution.
"The complexity of the reproductive system in these specimens raises the question of whether the investment in giant sperm cells might represent an evolutionarily stable strategy," said Renate Matzke-Karasz, a geobiologist at Ludwig-Maximilians-Universitaet in Munich, CNN reported.
The study believes that the finding will help scientists in figuring out the evolutionary pathway taken by these organisms. Researchers claim in the study that the discovery provides "unprecedented insights into an unexpectedly ancient and advanced instance of evolutionary specialization."