Tuesday, September 16, 2008

Shark Eggs? I Didn't know this.

Crazy shark eggs

Discovery Channel

September 16, 2008

Did you know that sharks lay eggs? Deep-sea catsharks and chimaeras lay some of the strangest eggs of all. If you're a beachcomber, you may have seen these leathery "mermaids purses"

Sharkeggcase_heterodontus_francisci

washed up on shore. 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 catsharks and chimaeras 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's some examples. 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 it wedge it in place between the rocks until its ready to hatch.

Ghostsharkegg_

Ghost shark eggg case. Photo credit nuytsia






0 Comments: