This document discusses sexual reproduction in animals. It differentiates between internal and external fertilization, and describes three types of embryonic development: oviparity, viviparity, and ovoviviparity. External fertilization occurs outside the female body, while internal occurs inside. Embryonic development can involve laying eggs (oviparity), giving live birth after eggs develop inside the female (ovoviviparity), or giving live birth with the embryo nourished by a placenta (viviparity).

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KINGDOM: ANIMALIA
SEXUAL REPRODUCTION
CHRISTHARINA SG
sgchristharina@preuni.unimas.my

2. http://farm9.staticflickr.com/8448/7991284064_9281a6e1f4_z.jpg
1. Differentiate between internal and external
fertilisation
2. Differentiate the three types of embryos’
development
3. Briefly describe the mating behaviour and the
reproductive organs involved
Learning
Objectives:

3. Fertilization can
be internal or
external
Animals can be grouped into three categories based
on the embryonic development:
1. Oviparity
2. Viviparity
3. Ovoviviparity
http://farm4.staticflickr.com/3444/3268077745_fd24bd675f_z.jpg

4. External vs Internal Fertilisation
EXTERNAL INTERNAL
Sperms cell unites with the egg cell outside
the female body
Sperms are deposited in or near
reproductive tract and the union takes
place within the female body
Environmental cues and body chemicals
such as pheromones ensure sperms and
eggs released at the same time and in close
proximity
Requires complementary mating behavior
and reproductive organs between the two
sexes.
Characteristics of aquatic animals such as
coral, Hydra, fish and amphibians (frogs,
toads)
Characteristic of salamander (amphibian),
reptiles, birds and mammals (higher
vertebrates)
Large numbers of eggs but low survival rate Small numbers of eggs but high survival
rate
Massive zygotes Fewer zygotes
Lack/No parental care Parental Care
High number of gametes Low number of gametes
Eggs lack of covering; jelly like membrane
for amphibian
Amniotic eggs were covered with
calcareous shells

5. EXTERNAL INTERNAL
Sperms cell unites with the egg cell outside
the female body
Sperms are deposited in or near
reproductive tract and the union takes
place within the female body

6. Environmental cues and body chemicals such
as pheromones ensure sperms and eggs
released at the same time and in close
proximity
Requires complementary mating behavior
and reproductive organs between the two
sexes.
A Male and Female common frog in amplexus. The
purpose of amplexus is to ensure the male is in the optimal
position to fertilize the female’s eggs as she lays them.
Foam nest

7. Massive zygotes Fewer zygotes
Frogspawn

8. High number of gametes Low number of gametes
Fish gametes
Frog gametes

9. Lack/No parental care Parental Care
Exception!!
A female frog that swallows its eggs or
carrying on the back to protect them.
A female salamander (amphiumas) coiled
around her nest to protect the egg from
predators
egg
Where is
mommy and
daddy?

10. Parental care is a diagnostic character for aves and
mammals
http://mariannedenazareth.blogspot.com/2011/08/parental-care.html http://www.dreamstime.com/stock-photography-parental-care-image8250792

11. Oviparity Ovoviviparity Viviparity
Lay eggs Eggs developed in female’s body until
hatch
Live birth
Development of the
embryos in female’s body
External and internal
fertilization
Internal fertilization Internal fertilization
No nutrition is provided to the
developing embryo except for egg’s
yolk
The embryo obtains its
nutrients and oxygen from
the female via placenta.
After live birth the young
can survive with the
supervision from its mother
The embryos of animals undergo three types of development
as below:

12. Oviparity
https://i.ytimg.com/vi/ihaR-_SDemE/maxresdefault.jpg
http://www.findaspider.org.au/find/spiders/images/SalticidInsectEggs.jpg
Yolk in the eggs provides
nutrients that will sustain
development of the young.

13. http://www.bio.gc.ca/sharks/images/reproduction-fig14.jpg
Viviparity
Ovoviviparity
http://askwhy.co.uk/dinosauroids/wp-content/uploads/2012/03/snake_live_birth.jpg
The mother gives birth to
young that recently hatched
in her body. The young were
nourished by egg yolk, not by
their mother.
Embryo are nourished by the
placenta; the organ which
allows nutrients from the
maternal blood to diffuse to
the embryo, and expelled at
birth.