Various steps involved in a sexual reproduction in animals are:
1) Pre - Fertilization
2) Fertilization
3) Post Fertilization

Introduction:
Sexual reproduction is the process by which animals produce offspring through the combination of genetic material from two parents. This process involves several steps that contribute to genetic diversity and ensure the survival of the species. Here are the various steps involved in sexual reproduction in animals:

1. Gamete Production:
- In sexual reproduction, specialized cells called gametes are produced by each parent.
- In males, gametes are called sperm, and they are produced in the testes.
- In females, gametes are called eggs or ova, and they are produced in the ovaries.

2. Mating and Fertilization:
- Mating is the process in which the male and female individuals come together to transfer the sperm from the male to the female reproductive system.
- Fertilization occurs when a sperm cell successfully fuses with an egg cell, resulting in the formation of a zygote.
- Fertilization may be internal, where the sperm is deposited inside the female's reproductive tract, or external, where the eggs are fertilized outside the body.

3. Zygote Development:
- After fertilization, the zygote begins to divide through a process called cleavage.
- Cleavage leads to the formation of a blastocyst or embryo, which implants itself into the uterus in mammals or develops externally in other animals.
- The zygote undergoes further development, forming different germ layers and eventually developing into a fully formed organism.

4. Gestation and Birth:
- In mammals, the zygote develops within the mother's body during a period called gestation.
- The developing embryo receives nutrients and oxygen from the mother through the placenta or other specialized structures.
- Finally, the offspring is born through a process called parturition, ensuring its survival outside the mother's body.

5. Genetic Variation:
- Sexual reproduction promotes genetic variation in offspring.
- During gamete formation, a process called meiosis occurs, which shuffles and recombines genetic material.
- This recombination leads to unique combinations of genes in each offspring, increasing genetic diversity within a population.

Conclusion:
Sexual reproduction in animals involves the production of gametes, mating and fertilization, zygote development, gestation, and birth. This process ensures genetic diversity and contributes to the survival and adaptation of the species.