In most shark species, courtship involves biting the female to get her attention.
In some species, females have evolved skin nearly twice as thick as males to cope with the damaging mating rituals.
After courting the female, the males will generally bite the female’s pectoral fin to hold on to her.
Male and female sharks have paired reproductive tracts - two claspers (shark penises) and two uteri.
Male on the left with claspers circled. Female on the right.
Image from https://thefisheriesblog.files.wordpress.com/2014/07/female-shark-and-male-shark-with-claspers2.jpg
The male uses one clasper during mating. This clasper has a hook on the end that holds onto the inside the female.
You can see how this works in this video.
Once he has hooked in, he expels his sperm along with seawater inside the female’s reproductive tract.
Spiny Dogfish female reproductive anatomy. Shown are the cloacal opening, the vaginal chamber and the entrance to the two uteri.
Image from Hedrick et al., 2019
Spiny dogfish females have one of the longest gestation periods of any living vertebrate, nearly 2 years!
Spiny dogfish are ovoviviparous, meaning the offspring hatch from eggs inside the mother’s body. The foetuses then feed off yolk sacs in the uterus.
Once the female has given birth, she ovulates and is immediately ready to reproduce again.
References and Further Reading
Michael, S. W. (2005). Reef sharks and rays of the world. ProStar Publications.