Chondrichthyes show three types of reproduction...

• OVIPAROUS: LIKE FISH -- EXTERNAL FERTILIZATION OF EGGS

• OVOVIVIPAROUS: EGGS  KEPT IN MOTHER AND HATCH WITHIN MOTHER   -- EGG HATCHES IN BODY  - ENERGY FOR EMBRYO  SUPPLIED BY YOLK;  INTRA-UTERINE CANNIBALISM SEEN IN THE SAND TIGER SHARK WHERE THE FIRST BORN DEVOURS THE OTHER EMBRYOS

• VIVIPAROUS: PLACENTAL CONNECTION VIA UMBILICAL CORD

• Originally thought to be primitive fish, sharks are actually quite complex animals when further studied and have unparalleled sensory capabilities and an uncanny ability to survive through the ages.  Sharks are one of the oldest and one of the most successful and diverse vertebrate groups ever.

bharris@chat.carleton.ca