article : Asexual Reproduction Invertebrata Animal

Reproduction is a marvelous culmination of individual transcendence. Individual organisms come and go, but, to a certain extent, organisms "transcend" time by reproducing offspring. Let's take a look at reproduction in animals.

What is reproduction?

In a nutshell, reproduction is the creation of a new individual or individuals from previously existing individuals. In animals, this can occur in two primary ways: through asexual reproduction and through sexual reproduction. Let's look at asexual reproduction.

Gemmules of the freshwater sponge spongilla. Image courtesy of J. Houseman; BIODIDAC

Asexual Reproduction

In asexual reproduction, one individual produces offspring that are genetically identical to itself. These offspring are produced by mitosis. There are many invertebrates, including sea stars and sea anemones for example, that produce by asexual reproduction. Common forms of asexual reproduction include:

Budding

• In this form, an offspring grows out of the body of the parent.
  
  
• Hydras exhibit this type of reproduction.
  
  
  Hydra Budding
  Image courtesy of BIODIDAC

Gemmules (Internal Buds)

• In this form, a parent releases a specialized mass of cells that can develop into an offspring.
  
  
• Sponges exhibit this type of reproduction.
  
  
  Sponge Gemmmules
  Image courtesy of BIODIDAC

Fragmentation

• In this form, the body of the parent breaks into distinct pieces, each of which can produce an offspring.
  
  
• Planarians exhibit this type of reproduction.
  
  
  Planarian
  Image courtesy of BIODIDAC

Regeneration

• In this form, if a piece of a parent is detached, it can grow and develop into a completely new individual.
  
  
• Echinoderms exhibit this type of reproduction.
  
  
  Oral surface of a star fish.
  Image courtesy of BIODIDAC

Source : http://biology.about.com