Some species of sharks lay eggs, while others give birth to live young. About 40% of shark species, and all species of skates, lay eggs. The egg cases are usually attached to substrate, such as kelp or rocks, and the embryos are nourished from a yolk sac until it has all been absorbed and they push their way out into the world as fully-formed young. Shark species that lay eggs tend to be bottom-dwelling, and include the wobbegongs, horn sharks, and some cat sharks. The egg cases of oviparous sharks are usually leathery and have curly tendrils at the ends or are covered in fibers. Some sharks that lay eggs are:

• Small-spotted catshark (Scyliorhinus canicula)
• Nursehound (Scyliorhinus stellaris)
• Horn sharks
• Bamboo sharks
• Carpet sharks
• Zebra sharks
• Swell sharks
• Port Jackson shark
• Dogfish sharks
• Australian Swellshark

Most other sharks give birth to live young, called pups. Examples of sharks that give birth to live young include mako sharks, bull sharks, lemon sharks, and blue sharks. Great white sharks usually have only one or two pups at a time, but some of the other sharks can have a litter with up to 20 pups.