Introduction:
Animals have different modes of reproduction, which can be broadly categorized into two main types: sexual reproduction and asexual reproduction.

Explanation:
1. Sexual reproduction:
Sexual reproduction involves the fusion of gametes, which are specialized cells involved in reproduction. In this mode of reproduction, two parents contribute genetic material to form offspring with a combination of characteristics from both parents. Sexual reproduction has the following characteristics:
- Gametes: Specialized cells called gametes are produced by each parent. These gametes, known as sperm and eggs, are haploid, meaning they contain half the number of chromosomes compared to other body cells.
- Fusion of gametes: The sperm and egg fuse during a process called fertilization, resulting in the formation of a zygote. The zygote contains a complete set of chromosomes and develops into an embryo.
- Genetic variation: Sexual reproduction leads to genetic variation among offspring due to the combination of genetic material from two parents. This variation contributes to the evolutionary success of a species.

2. Asexual reproduction:
Asexual reproduction does not involve the fusion of gametes and only requires one parent. Offspring produced through asexual reproduction are genetically identical or clones of the parent. Asexual reproduction has the following characteristics:
- No gametes: Asexual reproduction does not involve the production of specialized gametes. Instead, offspring are produced through mitosis, which is a type of cell division that results in two identical daughter cells.
- Budding: In budding, a small outgrowth or bud forms on the parent organism. The bud eventually separates from the parent to become an independent individual.
- Binary fission: Binary fission is a form of asexual reproduction in which a single parent organism divides into two equal parts, each developing into a new individual.

Conclusion:
In summary, the two main modes of reproduction in animals are sexual reproduction and asexual reproduction. Sexual reproduction involves the fusion of gametes from two parents, leading to genetic variation among offspring. Asexual reproduction, on the other hand, does not involve the fusion of gametes and only requires one parent. Offspring produced through asexual reproduction are genetically identical to the parent.