The physical consequences of sperm gigantism (opens in new tab)

Males of the fruit fly Drosophila melanogaster produce sperm that are each, on average, a couple of millimetres long. Thousands of sperm are stored in a seminal vesicle of only about 200 µm in size. Although the evolutionary pressures underlying such extreme flagellar lengths have been investigated, the physical consequences of their gigantism remain unclear. Here we show that sperm are packed into a dense and highly aligned state. We also find that sperm exhibit system-wide collective materi...