Ovoviviparous animals are those that produce eggs which develop and hatch inside the female's body, so the young are born live but without a placental connection. The embryos are nourished by the yolk within the eggs rather than directly through the mother's body. After hatching internally, the offspring are born fully formed and able to survive independently.
Definition and Reproductive Strategy
Ovoviviparity is a reproductive strategy between oviparous (egg-laying) and viviparous (live-bearing with placenta) reproduction. Fertilization happens internally, and the eggs remain inside the mother until ready to hatch, but the developing embryo relies mainly on the yolk sac for nourishment, not a placenta. The mother's body provides protection and gas exchange, but not direct nutrition through a placenta.
Examples and Characteristics
Examples include some species of sharks, snakes, rays, certain fishes, amphibians, and insects. These animals benefit because their young are more developed and capable at birth compared to oviparous species. For instance, young rattlesnakes are born with fully functional venom glands shortly after birth. Ovoviviparous animals do not have an umbilical cord like viviparous animals do.
Differences from Other Modes
- Oviparous animals lay eggs that develop outside the mother's body, with embryos nourished solely by the yolk.
- Viviparous animals give live birth, with the embryo nourished directly by the mother via a placenta.
- Ovoviviparous animals fall in between, with live birth but embryo nourishment mainly from the egg yolk, and no placental connection.
This reproductive mode offers advantages such as protection of the developing young inside the mother and more developed offspring at birth, increasing their chances of survival.
