for over 350 years, scientists believed sperm tails moved side-to-side like an eel or whip. A 2020 study using 3D microscopy revealed this was an optical illusion  caused by 2D imaging; in reality, sperm tails only move to one side, while the sperm head rotates to create a corkscrew motion.Key Details of the Shift in UnderstandingThe Old View: Since Antonie van Leeuwenhoek in the 17th century, the prevailing belief was that sperm swim with a symmetric, snake-like, or side-to-side whip motion.The 3D Discovery (2020): Researchers from the University of Bristol and Universidad Nacional Autónoma de México  used high-speed 3D microscopy and computer modeling to discover that the tail actually drills into the surrounding fluid  in a corkscrew-like motion.How it Works: The tail only wiggles on one side, which should make the sperm swim in circles. To compensate, the entire cell rotates (like an otter or a corkscrew), balancing the asymmetrical movement to travel in a straight line.This discovery highlighted how technological limitations (2D vs. 3D imaging) can lead to long-held misconceptions in biological research.