Vampire sex rituals of deep sea fish

The murky depths off New Zealand reveal some really weird fish. For instance, the sex life of the deep sea angler fish:
'The female is the size of a tennis ball. It has big savage teeth, little nasty pin eyes ... and a rod lure off the top of its head with a glowing tip to coax in stupid prey.'
The male 'looks like a black jellybean with fins'.
When a male finds a female, he bites into her side, never letting go.
'He drinks her blood, in return for giving her sperm,' Dr Norman said.