If, as some fundamentalists believe, God created the world in six days, then they should revile Him as a Master of Perversion driven by unbounded sexual obsessions and an ungodly scorn for family values. By contrast, less doctrinaire folks might well venerate Him as a Libertine Greater Than the Mind Can Imagine. Hardt, whose fascination with the sheer variety and kinkiness of sex in the ocean is unbounded, would clearly be in the latter camp. 

A reef ecologist and Research Co-Director of Future of Fish, she details the sex lives of creatures ranging from the tiny shrimp-like, twin-vaginaed copepods to whales with eight-foot vaginal openings. The male copepod deposits his sperm with his fifth set of legs, while the male right whale probes the female with a bowed eight-foot penis that Hardt compares to the McDonald arch. The female doesn’t mind, and in fact welcomes in the penises of two males simultaneously. Monogamy is rare in the ocean.

The earlier chapters are somewhat soft-core, focusing more on the romance of mating than on the gritty details of copulation, but in the later hard-core chapters, the thrust and clash of genitals is rendered in lurid detail. Not that underwater romance is a bland matter of chocolate hearts and roses: Lobsters get in the mood by shooting copious jets of urine and licking each other with their taste-bud-studded feet. But they do eventually assume a conventional, more human position: “He braces himself with big front claws and tail pressing into the sand, and gently turns her onto her back. She assists by stretching out her tail to lay as flat as possible. Belly to belly, they then fan their swimmerettes vigorously as he inserts.” What he inserts into what rather dampens the romance-novel mood: the “first pair of modified swimmerettes, called gonopods, into her sperm receptacle.” But finally, we return to less clinical language: after “he completes several thrusting motions. . . . . he gently rolls her back over and sets her down.”

It’s a transgendered world down there, with many sea denizens born hermaphrodites, or born female, morphing into males, and back again–or vice versa. Cross-dressing cuttlefish are a fine example of this polymorphism. When a male is courting a female, the side of him that faces her displays zebra-striped male markings. His other side, where other males lurk, displays mottled-brown female markings, signaling that he’s just a gal, and not a threat to a guy competitor.

Hardt often warns how pollution, development, and overfishing are threats, sometimes a bit heavy-handedly. But in the end, she’s hopeful because of great progress in ocean protection via international agreements, more protected zones, and new technologies that provide unprecedented ways to monitor conditions in the briny deep.