Adaptations and Development During Reproduction in Animals

Running head: ADAPTATIONS AND DEVELOPMENT DURING REPRODUCTION
ADAPTATIONS AND DEVELOPMENT DURING REPRODUCTION IN ANIMALS
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1ADAPTIONS AND DEVELOPMENT DURING REPRODUCTION IN ANIMALS
Part A: Reproductive Adaptations
Reproduction is the process of producing offsprings by sexual or asexual methods.
There are many strategies that the animal adapts, like the structural, behavioural and
functional adaptations to improve the chances of fertilization and increase the survival rate of
the offsprings. Different species belonging to the animal kingdom has different reproductive
traits. Fertilization is the process of fusion of the male gamete with the female gamete to form
a zygote. Fertilization is of two types, internal and external fertilization. External fertilization
is the fusion of the male, and the female gametes outside the female body, this kind of
fertilization occurs in fishes like Salmon and Cod. Internal fertilization is the fusion of the
male and female gamete inside the female body; this happens in mammals like humans (Long
et al., 2014). The mode of giving birth also differs in the animal kingdom, and some give live
births, known as viviparity and some lay and hatch eggs, known as oviparity. All mammals
except Echidna and duck-billed platypus give live births of their offspring, while birds
reproduce by laying eggs and brood to hatch their eggs. The gestation period, which is the
period between conception and birth, differs among different species of the mammals. The
shortest known gestation period is of 12 days in Virginian opossum and the longest period is
known as of 22 months in Indian elephants (Imakawa, Nakagawa & Miyazawa, 2015). The
difference in the gestation period is due to the difference in growth before birth.
Part B: Development of the human embryo
The process of human embryo development begins with the cleavage of the zygote.
Blastula is the next stage of the zygote that contains 100 cells. The next step is the formation
of the body plan, where the cells of the blastula rearrange spatially to form the three germ
layers. This period of the development of the three layers of the cells from the blastula is
known as the gastrulation period (Buitrago-Delgado, Nordin, Rao, Geary & LaBonne, 2015).