I read Lilly's books back in the 1970s (after I saw the film The Day of the Dolphin, which was also loosely based on his experiements). Pretty wild stuff!

There was a story on Radiolab, told by the woman who lived with the dolphin and was charged with trying to teach him English: https://www.youtube.com/watch?v=Pqo.....EyoQY&t=5s

She directly addresses the "Sex" part (Basically, dolphins are horny suckers) and it includes fascinating recordings of her attempts at teaching him, and his attempts at English, which were actually pretty impressive.