1. Animal Reproduction
and Development

2. 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.

3. Asexual Reproduction
• In asexual reproduction, one individual
produces offspring that are genetically
identical to itself. These offspring are
produced by. There are many
invertebrates, including sea stars and
sea anemones for example, that
produce by asexual reproduction.

4. Types of Asexual Reproduction
• Budding - an offspring grows out of the body of
the parent.
• Gemmulation - a parent releases a specialized
mass of cells that can develop into an offspring.
• Fragmentation - the body of the parent breaks
into distinct pieces, each of which can produce
an offspring.
• Regeneration - if a piece of a parent is detached,
it can grow and develop into a completely new
individual.

6. Sexual Reproduction
In Sexual Reproduction, Two
Individuals Produce
Offspring That Have Genetic
Characteristics From Both
Parents. Sexual
Reproduction Introduces
New Gene Combinations in
a Population.

7. Gametes
•In Animals, Sexual Reproduction Encompasses
the Fusion of Two Distinct Gametes to Form a
Zygote. A Type of Cell Division Called Meiosis
Produces Gametes. The Gametes Are Haploid
While the Zygote Is Diploid. In Most Cases, the
Male Gamete, Called the Spermatozoon, Is
Relatively Motile and Usually Has Flagella. On the
Other Hand, the Female Gamete, Called the
Ovum, Is Non-motile and Relatively Large in
Comparison to the Male Gamete.

9. Types of Fertilization
•Oviparity – internal fertilization, deposited outside the
body to complete development
•Oviviparity – internal fertilization, embryo still
nourished by yolk
•Viviparity – internal fertilization, nourished directly
from mothers blood and later given birth

10. Patterns and Cycles
Reproduction and Is Subject to Certain Patterns and
Cycles Which Are Oftentimes Linked to
Environmental Conditions, Which Allow Organisms
to Reproduce Effectively. For Example, Many
Animals Have Estrous Cycles That Occur During
Certain Parts of the Year So That Offspring Can
Typically Be Born Under Favorable Conditions.
These Cycles and Patterns Can Be Controlled by
Hormonal Cues As Well As Other Seasonal Cues
Like Rainfall. All of These Cycles and Patterns Allow
Organisms Maximize the Chances of Survival for the
Resulting Offspring.

12. Embryonic Development
•Gestation Period lasts about 9 months
•Divided into fetal and embryonic period
•Embryonic period starts with fertilization and lasts 8 weeks
•Fetal period lasts 6 ½ months

13. Stages of development
• Fertilization - Includes penetrated
oocyte, ootid, & zygote. Pronuclei
appear.
• Cleavage-Series of Cell Division
• Gastrulation - Morphogenetic
movements to form primitive germ
layers
• Organogenesis – Primary organs
formed