Animal Life Cycle Stages

Study Notes

The animal life cycle typically consists of the following stages:

Direct Development: Young resemble adults and go through a series of molts as they grow (e.g., humans, birds)
Indirect Development: Young undergo a series of physical transformations before reaching adulthood (e.g., frogs, insects)

Genetics: Inherited traits can influence the life cycle
Environmental Factors: Temperature, nutrition, and other environmental factors can affect the life cycle
Evolutionary Pressures: Selection pressures can shape the life cycle over time

The life cycle begins with fertilization, where a sperm cell fertilizes an egg cell, forming a zygote that undergoes multiple cell divisions.
The embryo develops and grows inside the egg during the egg stage.
The larval stage begins with the hatching of the egg, and the larva undergoes a series of molts as it grows and develops, often looking different from the adult form.
The larva transforms into a juvenile, which resembles the adult form, and continues to grow and develop during the juvenile stage.
The juvenile reaches physical maturity and becomes capable of reproduction during the adulthood stage, marking the beginning of the reproductive cycle.
The adult animal reaches the end of its reproductive cycle, and physical abilities decline, leading to death and the end of the life cycle during the old age stage.

Characterized by young resembling adults and undergoing a series of molts as they grow.
Examples include humans and birds.

Characterized by young undergoing a series of physical transformations before reaching adulthood.
Examples include frogs and insects.

Genetics
Inherited traits can influence the life cycle.
Environmental Factors
Temperature, nutrition, and other environmental factors can affect the life cycle.
Evolutionary Pressures
Selection pressures can shape the life cycle over time.