by Peter Etnoyer
Sharks lay crazy eggs, but deep-sea catsharks and chimaeras lay some of the strangest eggs of all. If you’re a beachcomber, maybe you’ve seen these leathery "mermaid’s purses" washed up onshore. Did you come across any this summer? If you’re real lucky the rare and unique ones will wash up after a storm.
The egg cases of deep-sea sharks are adapted for survival in a cold, dark environment with little or no parental care. Their form follows their function- to remain in-place
and well-ventilated. This is no easy task in the deep water of the
continental shelf! Swift currents and predators abound.
Here are two examples, below. Ghost Shark egg cases from Tasmania resemble a kelp frond. Ghost sharks swim as deep 220 meters, and forage in the shallows at dusk. The Horn Shark swims to 150 meters. It lays eggs, too, but these are quite different. They take the form of a corkscrew, or auger, to help wedge it in place between the rocks until its ready to hatch (below).