- Protects the Gametes: Internal fertilization ensures the protection of gametes from the external environment. Terrestrial environments can be harsh and full of potential threats, such as desiccation, temperature fluctuations, and predators, which could damage or destroy the gametes. By keeping the gametes inside the body, organisms can prevent exposure to these hazards, helping ensure successful fertilisation.
- Prevents Desiccation: For many land-dwelling organisms, water availability can be a significant challenge, especially in arid or semi-arid environments. Internal fertilization enables organisms to conserve water since it does not require external water for gametes to meet and fuse. This water conservation is crucial for species that live in habitats where water scarcity is a significant factor.
- Enhances Fertilization Efficiency: Internal fertilization allows for close proximity and direct contact between the gametes, increasing the chances of successful fertilisation. The internal environment provides a more controlled and suitable setting for fertilisation, free from external disturbances or interference. This increased efficiency is beneficial in ensuring the continuation of the species in challenging terrestrial conditions.
- Supports Embryo Development: After fertilization, the developing embryo can receive nourishment and protection within the female's body. Terrestrial environments can be unpredictable and expose embryos to various stressors like extreme temperatures, fluctuating humidity, and predation. Internal fertilization provides a stable and nurturing environment for the embryo's development, enhancing the chances of survival.
As a result, internal fertilization has evolved as a significant adaptation for numerous land-dwelling species, helping them overcome the challenges of terrestrial life and ensuring their reproductive success.