Enjoyed learning about sharks. I thought I knew a little about them, because I always lived near the sea, and enjoyed boating and fishing. I used to collect shark teeth and marine fossils as a child.

I had no idea at all about their reproduction. Interesting about their resistance to cancer and circulatory disease. As the article suggests there is a great deal to be learned.

This direct link might be helpful-

The Evolution of Elasmobranchs (Sharks, Rays and Skates)