The answer is , because one cell divides to form two identical cells.
Shark,big fish, small fish,algae,plankton hope this helped
<span>One of the essential early steps in the inventing process is creating a prototype--which, simply defined, is a three-dimensional version of your vision. Creating a prototype can also be one of the most fun and rewarding steps you'll take. That's because developing a prototype gives you the opportunity to really tap into your creativity, using those skills that inspired your invention idea in the first place. And whether you're making your prototype at home or hiring the services of an engineer, seamstress or machinist, it's truly exciting to see your idea transformed into something tangible and real.</span>
To know where it rightfully belongs to. Variation of certain traits is caused by multiple factors of an individual of the same kind. Depending on their physical appearance, their environment and nature of survival.
Hope this might help.
