Final answer:
Sharks reproduce through ovoviviparity, oviparity, and viviparity, with oviparous sharks laying eggs outside their mother's body and nutrient-rich embryos.
Step-by-step explanation:
The mode of reproduction in sharks varies considerably within different lineages. Sharks exhibit three main reproductive strategies: oviparous, ovoviviparous, and viviparous.
1. Oviparous: Some sharks are oviparous, laying eggs outside the body. The eggs develop in external structures known as mermaid's purses or egg cases until they hatch.
2. Ovoviviparous: In this mode, the eggs develop and hatch inside the female's body, but the young sharks are nourished by the yolk sac and not directly from the mother. The mother gives birth to live young.
3. Viviparous: Viviparous sharks give birth to live young, and the embryos are nourished directly by the mother through a placental connection or yolk sac.
These reproductive adaptations contribute to the diverse life histories and survival strategies observed among shark species.