The term sperm is derived from the word spermos (meaning “seed”) and refers to the male reproductive cells. Sperm cells are the smaller gametes involved in fertilization. In these types of sexual reproduction, there is a marked difference in the size of the gametes with the smaller one being termed the “male” or sperm cell. A uniflagellar sperm cell that is motile is also referred to as spermatozoon, whereas a non-motile sperm cell is referred to as spermatium. Sperm cells cannot divide and have a limited life span, but they can fuse with egg cells during fertilization to form a totipotent zygote with the potential to develop into a new organism.