From Ancient Greek σπέρμα genitive σπέρματος here "semen" + ζωή "life" + εἶδος "kind, appearance", Latin spermatozoon, spermium.
Sperm is a male sex cell that forms in the testis and is part of the seminal fluid, sperm (milk). The spermatozoon usually has a rod-shaped head with DNA and a small amount of RNA, a middle part and a tail. Sharks, sturgeons and some other fish have an acrosome in front of the sperm nucleus, while bony fish do not have one. The length of the spermatozoon of most bony fish is 40-60 microns. The spermatozoon remains active in water for several days in Pacific herring, 10-15 min in sturgeon, up to 3 min in carp and 45 s in salmon.