Sharks - Oviparity

Oviparity refers to the several shark species that lay eggs instead of giving birth to live young. These are the minority as most species ore ovoviviparous.

Once the females eggs have been fertilised inside her body (as all fertilisation is internal in sharks), she lays them outside, i.e. in the ocean.

Some species ensure that their eggs are significantly more protected by enclosing them in a leathery case, known by many children and beachgoers as a Mermaid’s Purse.


Close up of a sharks egg.

Advertisements

For additional protection, some sharks push these cases into rock crevices using a corkscrew method. The leathery exterior is hardy enough to handle the pressure as well as the wear and tear, while the eggs are nestled safely inside. This makes it almost impossible for other fish to access or penetrate the eggs’ cases. These cases often wash up on beaches and shores and appear black and elongated.

The eggs are filled with a particularly nutritious yolk, ideal for the development and sustenance of beable shark pups. Other fish eggs do not have this yolk, which plays a role in the resulting poorly-developed babies, many of which die before maturing. In contrast, shark pups are hatched strong, beable and independent of their mother’s care and nursing. It is not known exactly how long it takes for the pups to develop to the point of hatching, but it is certainly somewhat extended to allow for sufficient maturation. Once hatched, the pups will each go their own direction and will begin their life of hunting, mating and (in some cases) migrating.

Well known oviparous shark species include the Horn Shark, Port Jackson Shark, Zebra Shark and Bullhead Shark.

Advertisements