Reptiles and fish such as sharks have the good sense to have both sexes have a vulva. That is the male organs tuck themselves away behind folds.
About 20 years ago some guy's pet, Gwendolyn, got out. His pet alligator. She was captured and her mouth was wired shut. I saw the clip on TV of the man suffering that Gwendolyn was bleeding and "You can see she's scared! I can't watch this," and he cried.
He did not keep his pet in a cage. She lived in the house and sometimes slept in bed with him.
The governor of Florida was a cracker, Lawton Chiles
. He got a special law passed making an exception for Gwendolyn and she was returned.
But the biologists had to tell him that Gwendolyn was really a guy.
In The City and the Stars
(1956) Arthur C. Clarke wrote of Earth a billion years in the future. The sun heating up has dried the seas and the remnant of the human race is content to live in one surviving enclosed city with self repairing mechanisms. The people are not born but manufactured as necessary, with minds derived from older people who died. They have technological reincarnation. Alvin, the hero, is the first individual made from scratch in millions of years. The humans have created a society recognizably human and for that they need 2 sexes because we can't have a human culture without romance and sex. But like reptiles the males have sex organs hidden away until they are needed for making whoopie.
The story is his rewrite of his own Against the Fall of Night