The female bedbug has no sexual opening. To get around this small problem, the male uses his curved penis to drill a vagina into the female.
The female Praying Mantis eats her mate after sex. During the act the female will hook her large arms around to hold him in place and start nibbling away. The sex drive is so strong in the male that he can continue to copulate even if his partner gets a little peckish before he's finished.
The male tick doesn't have a penis. Instead, he uses his nose to sniff out the females vagina. Once he's made it large enough by poking his nose around, he turns round and deposits his seamen. To finish the job off, he then turns round again and pushes the seamen inside with his trusty nose.
The oyster is usually ambisexual. It begins life as a male, then becomes a female, then changes back to being a male, then back to being female. It may go back and forth many times.