Pups of the great hammerhead shark are born following an 11-month gestation period. Hammerheads only reproduce once a year and give birth to live young. A yolk sack sustains the developing embryos initially and later transforms into a structure called a pseudoplacenta that functions similarly to a mammalian placenta.
The great hammerhead is the largest of the nine species of hammerhead shark. It can grow to 20 feet in length and weigh up to 1,000 pounds. As an apex predator, the great hammerhead has no natural enemies and eats whatever it can catch, including herrings, rays and even other sharks. The flattened head of this shark is shaped so that its electricity-sensing organs can better detect rays on the seafloor.