Diversity

2. Sex Cells
 Egg: big size, immobile, there are only a few. Inside
the egg there are nutrients for the embryo.
 Sperm cell: small size, mobiles, there
are many and are produced at all times.

3. Fertilization
 External fertilization: expel sex cells into the water.
How do they avoid the risk of not finding the other sex cell?

4.  Internal fertilization: sperm cells are expelled inside
the female body.
What is the advantage?

5.  This type of fertilization requires courtship and
intercourse.

7.  Disney Nature Minuto 24.

9.  Monogamy
 Polygyny
 Polyandry
An individual has one
partner during their
lifetime or at any one time.
A male has more than one
female.
A female has more than
one male.

10. Sexual Dimorphism
 Males and females of the same species are different.

11.  It doesn´t occur in every species...

12. Animals exhibit
different
strategies and
social
interactions..

13. Ovuliparous
 They release sex cells into the water and the embryo
develops there.

14. Oviparous
 The embryo´s development occurs inside an egg,
outside of the female´s body.

15.  Some of them incubate
the eggs.

16.  Others simply bury them!

17. Ovoviviparous
 They keep the eggs inside their body.

18. Viviparous
 The embryo´s development occurs inside the female´s
body (pregnancy).

19.  Marsupials: the offspring are born very inmature and
they are kept inside a “bag” in the mom´s body
(marsupio) where the mammal glands are. There they
complete their development.

20.  Placental: the development occurs inside the uterus.
The mother has a connection with the baby through
the placenta.

22. Development
 Direct development: they only change in size, but the
characteristics are pretty similar between an adult and
a baby.

24.  Indirect development (metamorphosis): adults are
very different from youngsters.

26. Reproductive Strategies
 “r” strategy: have a large number of offspring but they
don´t take care of them.

27.  “K” strategy: have few offspring but they look after
them until they reach the reproductive age (they
become adults).

31.  Some of them preffer
to get a nanny!