Jump to ratings and reviews
Rate this book

Sex in the Sea: Our Intimate Connection with Sex-Changing Fish, Romantic Lobsters, Kinky Squid, and Other Salty Erotica of the Deep

Rate this book
Beyond a deliciously voyeuristic excursion, Sex in the Sea uniquely connects the timeless topic of sex with the timely issue of sustainable oceans. Through overfishing, climate change, and ocean pollution we are disrupting the creative procreation that drives the wild abundance of life in the ocean. With wit and scientific rigor, Hardt introduces us to the researchers and innovators who study the wet and wild sex lives of ocean life and offer solutions that promote rather than prevent, successful sex in the sea. Part science, part erotica, Sex in the Sea discusses how we can shift from a prophylactic to a more propagative force for life in the ocean.

288 pages, Hardcover

First published February 9, 2016

121 people are currently reading
2576 people want to read

About the author

Marah J. Hardt

3 books33 followers
A coral reef ecologist by training, Marah J Hardt keeps one foot wet in the field, while the other roams the worlds of creative storytelling and problem-solving, with a focus on ocean conservation issues. Currently a Research Co-Director for Future of Fish/Flip Labs, Marah assists entrepreneurs and innovators with finding solutions to the global overfishing crisis. Her past work includes ecological, historical, and social science research on a range of subjects, from artisanal fisheries to climate change impacts on ocean life. Her articles and book chapters have appeared in academic and popular media, such as Scientific American and The American Prospect. She received her PhD in Marine Science from Scripps Institution of Oceanography in 2007, and a B.A. in History of Science from Harvard University in 2000.

Ratings & Reviews

What do you think?
Rate this book

Friends & Following

Create a free account to discover what your friends think of this book!

Community Reviews

5 stars
273 (37%)
4 stars
260 (35%)
3 stars
154 (20%)
2 stars
37 (5%)
1 star
11 (1%)
Displaying 1 - 30 of 143 reviews
Profile Image for Alex ☣ Deranged KittyCat ☣.
654 reviews434 followers
February 22, 2018
I had just spent the past two hours watching corals spawn. But that event looked so unlike sex that I never expected the aftermath to smell like it.


Sex in the Sea: Our Intimate Connection with Kinky Crustaceans, Sex-Changing Fish, Romantic Lobsters and Other Salty Erotica of the Deep is a very entertaining and interesting book. The title describes the book perfectly as we get a look at the matting rituals for marine life.

We get to learn some interesting facts, such as: adult male sperm whales make the loudest biologically sound on earth (they seem to keep people in Seattle up); lobsters use urine to express their desire to mate; seahorses act like chaste Victorian singles during their courtship; the male whitespotted putterfish makes the most spectacular nest. And there are many more examples of curiosities regarding sex in the ocean.

What I like most about Marah J. Hardt's book is how she links sexual marine behavior with the importance of preserving these species. People fish more than ocean species can reproduce. So we should slow down and let them frolic to their heart's desire.

Also, did you know there are seahorses being bred just to be used in aquariums or in medicine? That sounds creepy.

I recommend this book to anyone looking for an easy and entertaining science read. I think it would also make for an interesting present.

*I thank Marah J. Hardt, St. Martin's Press, and Netgalley for this copy in exchange for an honest review.
Profile Image for ❀Aimee❀ Just one more page....
444 reviews93 followers
January 9, 2016
What an entertaining, educational, and forward thinking work!

Marah J. Hardt reveals the curious mysteries of marine sex life in fascinating ways. Each chapter begins with a short fictional tale of the enigmatic sex life of a particular marine animal written like a romance novel. These are amusing and are a fantastic way to start each section.

I was captivated to the pages as she unfolded the intriguing details that marine life goes through seeking a mate, courtship, intercourse, and post-sex.

Marah is an artful and descriptive writer as well as having an intimate knowledge of her subject matter. Here's one example (I was provided an uncorrected advanced copy and quotes may not match the final edition of the book).
If you want to grow your orgy numbers, nothing beats a full-blown belly flop to attract the neighbors...[they]momentarily defy gravity and their watery roots to burst forth from the sea in spectacular displays. Nearly all of the multiple species of mobulas seem to have this penchant for aerial acrobatics, leaping up to six feet out of the water before splashing down with a crack at the surface...Looking down through the clear waters at a seasonal aggregation of hundreds of thousands of these rays is like watching a moving M. C. Escher painting:the diamond shapes of the mobulas create a deformed checkerboard that appears at least a dozen layers deep. With each layer moving at a slightly different speed, it is hard to know where to focus. Until they leap. Then it's all eyes on the flyer.




Reading felt like listening to a friend chatting about marine life. There was this spark of excitement to her tone... She is very much like the few amazing college professors I had, who enthralled students with creativity and enthusiasm.


I stayed close to my computer while reading to find videos or images of everything she was describing. Here are just a few choice topics she covers:

Learn what urine has to do with lobster seduction...


See how progressive seahorses really are with the males being the pregnant ones.


Learn how the tiny whitespotted pufferfish create these amazing nests over 6 feet in diameter by wiggling his butt.


Cuttlefish often pretend to be female to sneak in past an unsuspecting larger male to mate with his female.


See how frequently marine life changes sex, and learn all about the genital record breakers of the ocean...largest, longest, detachable, re-growable penises abound.
Sea Slugs are detachable and grow back in a day:


Barnacles (the longest penis ratio for body length) and Queen Conches and are long out of necessity:



Sharks have the most impressive claspers out there. For example, a ten foot great white might easily have a pair about three feet long...yeah....here they are below.


Marah also describes how very susceptible marine life is to changes in their environment. From what marine biologists have already determined, humans have inadvertently caused dramatic declines in many species. Mating must often occur in very precise environments, many of which are significantly effected by humans. She gives this information in the best way I've ever experienced. So many books about human's negative effect on the life of the planet come across as preachy, but Marah avoids this pitfall with ease.

Do yourself a favor and dive into this gem of a book!

Thank you Netgalley and St. Martin's Press for a free digital copy in exchange for an honest review.
Profile Image for Vivian.
2,919 reviews484 followers
December 4, 2015
Humorous, but not silly.

Sassy introduction that lays out the issue of terrestrials' dependence on the sea for not only protein, but water filtering and erosion blocking. Loss in fertility of the seas impacts humans. The tongue in cheek tone and the analogies are meant to be accessible to laypersons through humor and sex, and the message comes through without seeming didactic.


--Spawning coral during a full moon. Only happens once a year since it takes enormous reserves of energy to produce the eggs and sperm.

Strong emphasis on the dangers of overfishing during mating aggregations and near seamounts which act as beacons. Additionally, though parthenogenesis might seem like reproduction of the gods in some species facing 95% population reduction in the last 50 years, it is critical even if limiting the gene pool.

The mystery surrounding blue whales song pitch drop and the possible correlation to the whaling ban and recovering populations is intriguing. Less distance required, now advertising size. Animals are adapting as quickly as they can to changing conditions, but we still need to be mindful, diligent and make conscious decisions on the costs and benefits of our actions.

More carbon dioxide (fossil fuel burning) leads to a change in the ocean pH to more acidic. Animals that rely on chemical processes to attract mates are affected. And some chemicals mimic pheromones, yet don't provided what the animals need. Climate change is eroding beaches with larger storms thereby reducing area for spawning grunions to egg laying turtles. The importance of population densities in external fertilization mating species means that even a few feet of distance between animals can result in failure.

The different strategies animals employ to pass on their genes are amazing. Truly, from subterfuge to straight out switching genders to tip the balance in their favor. It also highlights problems of fishing strategies which target the largest fish. In protandrous, if you take the biggest, you take the female and essentially eliminate future generations. Not much better for protogynous, where the shift to male is accelerated and reduces egg production. The only ones which seem to be all right are fish which change genders depending on their local population. Also, by taking the largest, you see a genetic shift to smaller species as the best breeders are eliminated.

Shows the interconnectedness of species and how when one fails due to increased sedimentation it affects the other. It's an ecosystem.

Shout for the US Virgin Islands! Permanent ban on aggregation fishing of the red hind grouper has seen population recovery--WOOT!

Eat what the ocean provides not what we want to eat. Eating on demand is stressing species to the break point. All is not lost. Even with severely depleted numbers, the sea is resistant and species are fighting to survive. Changing methods of harvesting and our consumptions habits are critical. But even the near extinct white abalone is catching a break. Dedicate marine labs have been attempting to get them to reproduce, with mass sperm and eggs releases and proximity key it was one lucky break and a pipette in hand that gave researchers their first new twenty animals and its only been increasing each year. With luck and hard work they might be back in the wild again.

This is not a hardcore science read, but if you want to understand the various and radically different reproductive strategies marine animals use then this is very engaging. Life is amazing and the sea shows it in all its glory from projectile penes, sex teeth, gender swapping, dueling penes to dual penes, double penetration, cannibalism, virgin births, and parthenogenesis.

After reading this I've come to the conclusion that human reproduction is really boring. BORING.

Favorite quote:
Fish, like most other species on the planet, would rather reabsorb their gametes than waste them on an unworthy mate.


~Copy provided by Netgalley~
Profile Image for Tyler Gray.
Author 6 books276 followers
November 15, 2020
DNF on page 72. I can't with the weird cissexism in this book anymore. Yes, my trans self is getting angry at this book and I can't deal with it anymore. I'd understand some things being uncomfortable when discussing sexual dimorphism but the author tries to make "funny" scenarios where humans act as fish do and apparently isn't able to do so without being very cissexist. Conflating sex and gender...saying things like "like us, they only have two genders" which...this came out in 2016...what's the excuse? Gender and sex aren't the same thing and even sex is a lot more complicated in us than that. There also seems to be a lot of bad stuff in this book about climate change but not really any actionable advice, which seems like an oversight. I love the ocean and marine life, but I can't do this book.
Profile Image for David Schwan.
1,180 reviews49 followers
November 4, 2017
Despite the title this is really a book about conserving the life in our oceans. The author presents example after example of how various forms of sea life reproduces--yet there is an underlying message of how humans get in the way of this reproduction and have caused the crash of many species. Not all is doom and gloom, the author gives examples of where with simple changes we have brought species back and can catch them in a responsible manner.

Warning--this book is not as easy a read as I would have expected.
Profile Image for Lena.
1,219 reviews333 followers
November 4, 2017
"Nothing encourages unleashing a torrent of semen like having to fire at the same time as another male."

"425 million years old. That’s the age of the oldest known fossil penis—a Johnson that left quite an impression."


♫ Lets talk about sex baby, let's talk about wild gametes. Let's talk about all the good things and the bad things in the sea. ♫

This book was entertaining, funny, educational, and compassionate. It was also frenetic, lol! Imagine your favorite professor on expresso gleefully shifting subtopics as new and interesting things/facts/fish occur to her. The book covered sequential hermaphroditism in parrot fish, eels, and clownfish giving a whole new spin to Finding Nemo. Orgies of all flavors were discussed from the grunion run to the full moon coral spawning. Sea creatures also use asexual reproduction and delayed reproduction. A "female brownbanded bamboo shark [in an aquarium] gave birth to a healthy young pup after nearly four years of celibacy." No one knew they could hold sperm that long.

My favorites were the whale threesome and the lobsters, oh my the lobsters! I had no idea sex could be both so funny and touchingly romantic. "In the world of lobster sex, nothing says “let’s get it on” like peeing in your lover’s face." (That wasn't what I considered the romantic part, just in case you were wondering.) Hardt takes a moment to cite studies proving lobsters feel pain, just like your dog/cat or kids, so boiling them alive is brutal. Scratch that from my personal menu FOREVER.

Without being heavy handed the author points out how we are being hard on the ocean and some of the many reasons we should care. Did you like that breath you just took? Thank diatoms, they "pump out about 20 percent of the global oxygen supply." One of the things I liked best was Hardts optimism, she gives many examples of where government regulations, grassroots efforts, and innovation have made positive changes. As she points out, "there's even a hashtag for it: #oceanoptimism." Best example:

"In Palau—the first country to ban commercial fishing of sharks in all its territorial waters—a recent economic evaluation estimated a single resident shark would generate nearly US$2 million over its lifetime compared to a couple hundred dollars finned and sold as meat." I want to visit Palau and give them a collective high five.

So what can you do besides buy this book? Hardt points out the easiest way you can help the ocean is by not always eating the same three fish, there are other fish in the sea besides tuna! It's time to make gastronomic discoveries and save the planet!
Profile Image for Shelby.
115 reviews
February 21, 2017
Don't let the conversational tone of this information-packed book fool you... There's a ton a learn from Marah Hardt and from all those different species getting it on under the sea. Not only does she shine a light into those dark depths and show how fluid sexuality and gender really are, she describes how human pollution affects the ability to reproduce and how declining numbers affect human food-supply. She also shows how climate-positive and species-specific protections have made a difference in sustaining our favorite dishes and medical technology, among other things. I highly recommend this book. It takes what might have been a dry subject and turns it into a fun read that really makes you stop and think about things we usually don't ever think about; like BOFFFF's.
Profile Image for Michele.
231 reviews
February 24, 2017
The topic was fascinating, the writing was lackluster. I probably would have enjoyed this book more if the writing style was more akin to Mary Roach, who treats even the most salacious topics with wit and her brand of dry humor that I find so appealing.
Profile Image for Mark Hartzer.
331 reviews6 followers
January 9, 2022
It's a shame that American high school studies have devolved into standardized testing and rote memorization because I think a book like Dr. Hardt's would be vastly more entertaining and educational than your bog standard sophomore biology text. Consider this sample from p. 136:

"With the help of some old-fashioned dissections and some new high tech tools, some researchers have begun to buck the trend and tease apart the myriad ways females of different species can manipulate sexual outcomes. Females exert such choice through a combination of behavior and some marvelous anatomical innovations. Vaginas, it turns out, can tell us a whole lot more than just how big a penis is. It's not easy to study a whale vagina. But with a little creativity and a Fed Ex account, it is possible."

I'm not going to spoil Ms. Hardt's lead in, so you will need to read it yourself, but there is a whole lot of tongue-in-cheek humor mixed in with some pretty serious science. This book may not be for everyone, but I think it would be an excellent gift for the intelligent and curious teen (and adult too).
Profile Image for Leah K.
749 reviews2 followers
May 17, 2016
Sex in the Sea: Our Intimate Connection with Sex-Changing Fish, Romantic Lobsters, Kinky Squid, and Other Salty Erotica of the Deep by Marah J. Hardt
278 pages

★★★★

Before reading this book, if you had asked me something that bored me, it would be fish. But I saw a fellow book nerd read this book and I was intrigued. I won’t lie…that word “sex” in the title helped. And oh am I glad I read this one. Yes, it deals with intercourse between sea animals but it deals with so much more as well. The author talks about the ecosystem and how it is effected by the slightest changes – mostly thanks to humans. And if sea life isn’t having sex, reproduction doesn’t happen, certainly not a good thing to keep biodiversity going. So along with fascinating tales on how the underwater world gets it on, she explains ways we can attempt to fix the issues humans have often caused.

I really enjoyed this book. It left me interested and laughing. It’s well researched but the author doesn’t always take herself seriously when discussing sex. She reminded me of the author, Mary Roach, of the sea. It kept me up later than it should have most nights and I didn’t like putting it down. It was a quick read overall and definitely worth the time to look into, even if you think you aren’t interested in fish and the sea.
Profile Image for Chloe A-L.
282 reviews20 followers
February 1, 2018
There's a LOOOOT of weird cissexism in this book, which is par for the course when discussing sexual dimorphism but the author also tries to make "funny" scenarios where humans act as fish do and seemingly isn't capable of doing that without being a huge cissexist. At one point she literally says "like us, the have only two genders" which, goddamn woman, this came out in 2016? No excuse for that. There's also a lot of bad news in this book and not a ton of actionable advice, and specifically NO actionable advice for poor people, or people who have been fisherman for generations and have their livelihood tied up in the fishing trade which seems like... a pretty big oversight. It doesn't surprise me that the author lives in boulder.
Profile Image for Josh.
367 reviews38 followers
December 10, 2016
I assigned this book to my upper level class in marine biology and I couldn't be happier about it. This book is incredibly engaging, and it was fun to hear the students remark about how much enthusiasm they had for reading it. Dr. Hardt really has a way with words, and some of her opening lines were so engaging (and hilarious) that I couldn't help but find myself searing for extra time throughout the day to read the book.

The book is factual, engaging and fun to read. It has a thoroughly listed bibliography at the end for people who want to read further, although I wish that these citations had been footnoted within the main text. I would have no reservation using this book again for class, nor about recommending it to my friends who have an interest in marine biology, or just an interest in the various ways it's natural to have sex.
Profile Image for Susan .
1,194 reviews5 followers
June 7, 2017
The science, descriptions and nuances of amazingly diverse sexual practices among sea inhabitants was fascinating. But I could not endure the writer's style in conveying the interesting stuff. It's as if the book was written by an adolescent boy science nerd. The chapter headers of "sex-sea soundtrack" suggestions were inane, as well as the pre-chapter "trivia". But what really made me simply give up reading was the constant....and I do mean constant... reference to "getting busy" and other immature sexual innuendos (wink, wink, nod, nod). I guess this style was meant to keep the material light, or maybe the author is appealing to teen-aged readers, but I found it to be just relentlessly annoying.
Profile Image for Nore.
827 reviews48 followers
February 22, 2018
While this was full of interesting information, very little of it was actually practical - I came away knowing much more about what has been done to protect ocean wildlife, but very little on what I could do to help. I do appreciate that I now know what to look for when purchasing fish.

But that oversight in itself isn't why I rated this two stars; what dragged it down for me was the unending stream of juvenile jokes and anthropomorphization - quite simply, a fish is not a human, and drawing associations between the sex fish have and the sex humans have is ridiculous. Add in some conflation of sex and gender, and we have a book that was grating to read.
Profile Image for Bria.
954 reviews82 followers
June 25, 2025
Most of what I want out of life is to learn about this kind of stuff. I only have 3 complaints:
1. This really calls for videos and pictures. I was going to read it on a plane but without the internet it was barely worth it, so I just slept instead.
2. Big black mark for bothering to put song suggestions at the beginning of each chapter but then on the chapter on penes where it's SPECIFICALLY noted that some mollusks have detachable penises and then not have the song Detachable Penis! Full star lost.
3. This isn't a complaint about the book, but about the world we live in, that it's such that you can't write anything about the ocean without it also being about conservation. Although I actually successfully came away optimistic, I'm still just generally mad that I can't just learn weird ocean facts (tm) in the void.
Profile Image for Sarah Fuller.
1,020 reviews15 followers
February 20, 2022
There’s a lot of fascinating information here and each section has a little fictional romance story to set the mood for the section. However, this was just not something I’ve cared about. Ever. To read.

This was a bookclub selection and it was a bit tortuous to finish.

If you like oceanography, this is great. The author also brings in marine life conservation, which was interesting as well. If you like that sort of thing.

Sorry. Just not my kind of read.
Profile Image for Craig Thomson.
Author 1 book2 followers
May 9, 2025
There's definitely some interesting stuff in here but it gets bogged down with repetition, failed attempts at humour and a sense of it's own self importance. Also, weirdly transphobic?
Profile Image for Patty.
731 reviews53 followers
December 31, 2015
I'm a huge fan of the genre that can be loosely described as "popular books about weird science"; it includes authors like Mary Roach and books like Parasite Rex or Sex on Six Legs. So obviously when I saw this book offered on NetGalley, I had to read it immediately.

I'm not sure how to summarize it, because really, the subtitle says everything you need to know. If you want to read about how much lobsters pee on each other during sex (answer: lots) or the octopus that can detach its penis and throw it like a dart at the females of its species, this is the book for you. The writing style is a nice mix of breezy and funny, while still conveying a good amount of scientific information. There's also a chapter at the end about how all this studying of sex has influenced conversation efforts. It was fairly optimistic, which is a nice change from the "EVERYTHING IS GOING EXTINCT AND NO ONE CAN EVER EAT FISH AGAIN" tone of a lot of current writing about overfishing and ocean pollution.

Overall, a fun read, though not particularly life-changing.

I read this as an ARC via NetGalley.
Profile Image for Sara.
235 reviews37 followers
December 19, 2017
I'm editing my review because I think I was a bit too harsh. I learned a lot in this book and some of it was incredibly interesting like how coral spawn or how the heck Do animals find each other in the vast ocean?? (The bit about very small Copepod was great!). Equally fascinating was the chapter on how some fish change sex to suit their evolutionary purpose and how some start male and others start female. The author also has some wit about her. Plus she gives excellent, practical ideas for helping save fish like limiting fishing during mating season and not capturing the biggest fish as she is likely a Big Old Fat Fertile Female or BOFFF.

I do have criticisms but I guess they're mostly in editing. Too many stories packed into one chapter made it hard to stay focused. Sub headings within the chapters please!!! In some chapters on mating and unusual anatomy pictures would have greatly clarified her points. It made it a little more difficult to finish.

Overall though you will not find a book like this out there so you should definitely try it out! Really neat stuff
Profile Image for Paul.
1,187 reviews40 followers
August 4, 2016
This could have been a 4 star book without the cutesy nonsense and pop science tactics what with the "sexy soundtracks" and inappropriate juxtaposition of animal behavior and human behavior. I also basically just zoned out whenever she started talking about preservation or conservation or whatever - it's not like it's a reasonable dialog, it's taken as axiomatic that one must preserve everything as it is right now and oh hey can I get some funding to study fish sex because it's critical for such and such whatever. I understand it's how science gets funded but I still don't care for it.

Anyway, it's a testament to the relatively high quality of the information in the book and the pace of the rest of it that I am somewhat pleased to have read it. Normally I absolutely can't stand that sort of nonsense, but it was tolerable here. It was also nice that Hardt knows how to keep herself out of the book - half the books by working scientists these days are about their personal journey to science and how they met their spouse and other balderdash that I don't care about.
63 reviews1 follower
December 15, 2015
I'm always urging the world to surprise me. This book did not disappoint, but rather left me in a constant state of wonder. Why has no one ever related this information to me before?
It could do just as well on the Sci-fi shelf. It's nearly a comprehensive guide to the oceanic world of sex, but not draggingly so. The author has a humorous side. No stone is left unturned--fish, barnacles, coral--you name it.
I utilized www.youtube.com to watch her descriptions in action. The videos demonstrated her well-chosen wording of events.
She includes a surprising array of human activities that play upon the survival or demise of the ocean populations. She also suggests options for repairing the mess we have created.
I will be watching for more books by this author. I don't often rate a book with 5 stars.

Thank You, NetGalley for the chance to read this book.
Profile Image for Makhda.
877 reviews146 followers
April 7, 2016
I don't come from Marine Biology background. But this book is really interesting. I learn a lot from this book. For example, Male seahorses are the pregnant ones. Wow. Mpreg in real life. And I keep checking google for the visuality.

I did feel confused at the beginning. But it doesn't take long before I could understand. I do recommend this book strongly for someone who love science.

*Copy was kindly provided by the publisher through Netgalley for an honest review*
Profile Image for Lea.
2,841 reviews59 followers
October 12, 2016
I loved this book! The author use humor - and some pop culture - to tell us about the reproduction of creatures, big and small, that live in the sea. It was amazingly fascinating! She talked about how climate change and humans are impacting their abilities. But in an unusual twist, the last section was about hope and what you can do.
The narrator was engaging and easy to understand. Listened at 2x.
Profile Image for Ryan.
91 reviews20 followers
February 5, 2016
An informative and in parts fascinating well written book.

3 stars due the fact it becomes repetetive in parts and didn't manage to keep my full attention all the way through.
Profile Image for Lauren.
23 reviews18 followers
August 6, 2016
A hilarious point of view to the intimate lives of fish and other ocean dwellers.
117 reviews
May 4, 2016
Am I the only one who hated this book? It fails as both biology and erotica and suffers from terminal cuteness.
10 reviews1 follower
March 13, 2017
Very interesting but I got fed up and am unlikely to finish it...
Profile Image for Jennifer.
411 reviews2 followers
August 22, 2017
Really great science writing which was a pleasure to read. It was also very funny, with anthropomorphized short stories starting off every chapter and lots and lots of puns.
Displaying 1 - 30 of 143 reviews

Join the discussion

Can't find what you're looking for?

Get help and learn more about the design.