REPRODUCTION IN ANIMALS | Class 8 Science Notes

6.2 Sexual Reproduction

Sexual reproduction in animals involves the fusion of male and female gametes to form a zygote, which develops into a new individual. Similar to plants, animals have specialized reproductive organs that produce gametes. In humans, males have testes that produce sperms (male gametes), while females have ovaries that produce ova or eggs (female gametes). The male reproductive system includes testes, sperm ducts, and penis. Sperms are microscopic cells with a head, middle piece, and tail; the tail helps in movement. Female reproductive organs include ovaries, oviducts (fallopian tubes), and uterus. The ovary releases a matured egg monthly into the oviduct. Fertilisation is the process where a sperm fuses with an egg to form a fertilised egg or zygote. This zygote undergoes cell division and develops into an embryo. Fertilisation can be internal (inside the female body) or external (outside the female body in water). Internal fertilisation is common in humans, cows, dogs, and hens, while external fertilisation occurs in aquatic animals like frogs and fish. The fusion of gametes ensures genetic mixing, leading to variation in offspring.

📊 Diagram: Fig. 6.2: Human sperm; Fig. 6.1: Male reproductive organs in humans; Fig. 6.3: Female reproductive organs in humans; Fig. 6.4: Human Ovum; Fig. 6.5: Fertilisation; Fig. 6.6: Zygote

🔗 Connection: This section leads to understanding fertilisation in detail, including internal and external fertilisation, and embryo development.