Are Sperm Alive?

[Dr E. Buxbaum]

Life can be defined by five characteristics:

1) Form: At any time there is a distinct border between a living organism 
and its environment, rather than a gradual transition. The form may 
change over time (amoebae), but it is always given.

2) Mobility: All life forms are mobile, at least at some stage in their 
life. Note that for example the orientation of a leaf towards the sun in 
plants counts as mobility.

3) Composition: Living organism maintain a concentration gradient of 
substances between them and their environment.

4) Propagation: Living organisms are able to reproduce themselfs.

5) Metabolism: Living organisms use energy from their environment to 
achieve the above mentioned functions.

Going through this checklist, you will find that sperms are alive, but 
for example viruses are not (no metabolism).