Sexual reproduction in animals:
Despite the many differences seen in animals,
the process that allows them to reproduce
sexually is the same:
- meiosis produces gametes
- male sperm combine with female egg
- a zygote is produced and then develops
into an embryo, which is a fertilized egg
during early development
- the embryo develops through mitosis
and cell division into a mature offspring
* draw figure 2.7 on page 52, answer 3
questions
For sexual reproduction to be successful,
there are two requirements:
1. both male and female gametes must
arrive in the same place at the same time for
fertilization
2. the zygote must receive adequate food,
moisture, warmth, and protection to develop
Mating: the process by which two members of a population
come together to combine their gametes for fertilization.
- for some animals, there is only one mating season each
year ………but why?
- it is usually timed so that the offspring
will be born when environmental conditions
are favorable for growth
- there are two main patterns of fertilization for animals:
1. external fertilization: the sperm and egg meet
outside the bodies of both parents (usually seen
in water-dwelling animals like fish & frogs)
* figure 2.12 p.55
* figure 2.14 p 56
2. internal fertilization: the sperm travels from
the male’s body into the females body to meet
the egg (usually seen in land animals like humans,
reptiles & birds)
- what do we have in common with deer?
- we are mammals, which both retain the
embryo inside the female for further
development and protection
- other animals, such as birds and reptiles lay eggs, which
they sit on to keep warm and to protect it
Hermaphrodite: an animal that has both male and female
reproductive organs.
- many worms, including earthworms are hermaphrodites.