This document discusses the history and principles of crab preservation. It was first documented in 1663 by Boyle and the first concept of sperm preservation was in 1760 by Lazzaro Spallanzini. The most significant discovery was the use of glycerol as a cryoprotectant by Polge and Smith in 1949. The key principles are freezing, storing, and thawing. Glycerol was accidentally discovered to protect cells from freezing injury. Crab preservation techniques have had a huge impact in many fields, especially reproductive medicine. Freezing injury has two components - direct damage from ice crystals and secondary damage caused by increased solute concentration as more ice is formed. Intracellular freezing is generally lethal but can be avoided with slow