Do sharks lay eggs or give live birth?
Sharks exhibit a great diversity in reproductive modes. There are oviparous (egg-laying) species and viviparous (live-bearing) species. Oviparous species lay eggs that develop and hatch outside the mother’s body with no parental care after the eggs are laid. The embryos are nourished by a yolk-sac inside the egg capsule. Viviparous species can be separated into two categories: placental (having a placenta, or true connection between maternal and embryonic tissue), or aplacental (lacking a placenta). Among the aplacental species, there are those whose embryos rely primarily on a yolk-sac for nutrition during gestation and those that consume yolk-filled, unfertilized egg capsules (oophagy). There is even one species, the sandtiger (Carcharias taurus), in which the two largest embryos that were fertilized first, consume the other embryos of the litter (adelphophagy). It has also been suggested that the young of some viviparous species may be nourished by uterine secretions during some par
