In his review of Juliet Eilperin's Demon Fish: Travels Through the Hidden World of Sharks, Theo Tait observes that when it comes to horrific sex, sharks give bedbugs a run for their money:
Larger male sharks have to bite or trap the females to keep them around during courtship; marine biologists can tell when a female has been mating because her skin will be raw or bleeding. The process is so violent that, come the mating season, female nurse sharks will stay in shallow water with their reproductive openings pressed firmly to the sea floor. Otherwise they risk falling prey to roaming bands of males who ‘will take turns inserting their claspers in her’ (the clasper is the shark version of a penis, found in a pair behind the pelvic fins). A litter of fifty pups will have anything from two to seven fathers.