by Michelle Reed

Created on: June 26, 2008   Last Updated: July 17, 2008

Every organism is born with a blueprint set of instructions called DNA. These instructions will set the events in motion for an organism to grow, develop and eventually reproduce. Unlike humans, other species have no control over how and when they reproduce, the method and cycle is part of their instructions. Whether or not sex is necessary for their reproduction depends on the organism. Their bodies will sense when the time is right and instinctively know what to do.

A vast majority of species use one of four methods of reproduction classified as asexual reproduction. The term asexual refers to reproduction without the use of gametes (egg and sperm) or sex cells. The first organisms on Earth reproduced this way to increase their populations; however this slowed their evolution due to a lack of genetic diversity.
Sexual reproduction allows for the exchange of alleles (genetic characteristics) from breeding with different members of the opposite sex, which follows natural selection to breed out undesired characteristics, and aid in the evolution of a species. Asexual reproduction will exchange the exact copy of alleles from a parent to a daughter organism.

Organisms like Parameciums and Amoebas are Protists. These organisms are one celled and live separately or in colonies. To reproduce, Protists use an asexual reproduction called fission. Some multicellular organisms, like worms, also reproduce by fission. The process of fission is the division of cells. A constriction of the plasma membrane folding inward and pinching itself in two to create two separate cells from one cell is called binary fission. Each cell contains equal amounts of structures and is exactly alike. For multicellular organisms that use fission there is a division along their bodies. This division can be longitudinal, asymmetrical or transverse. Worms can create more than one constriction along the length of their bodies and form a chain of individuals; this is known as multiple fission.

Another form of asexual reproduction is budding. Budding can be internal or external depending on the organism. Budding occurs in mostly sessile (attached to substrate) organisms. A Hydra is a freshwater organism that attaches itself to the underside of leaves. Many species of sponges and the Hydra perform external budding. Cells will quickly divide within them and develop on the surface of the organism. These cells will form branches or extensions of the parent as they develop into a new organism. The bud will

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