The male sperm has a normal length of 30 to 40 micrometers or 0.03 to 0.04 mm milimeters. Sperm counts, movement speed, length and head sharpness are indicators of healthy and viable one.
Sperm high counts increase the probability for survival of the whole cluster and the chance of one individual reaching the female egg. The movement speed is also another factor influencing the chance of reaching the female egg before the sperms dies. Sperms with sharp headshape gives its higher probability of piercing through the outer layer of the female egg.
The sperm tail's length influences its swimming speed but does not carry genetic material according to the medical internet.
However, the sperm tail looks like the spinal cord and the head looks like the brain. So basing on current observation, we can come up with a theory that the father carries the bone protein making instructions and half of the brain while the mother carries the other half of the brain and the muscle protein making instructions.