Aquagenesis: The Origin and Evolution of Life in the Sea

by Richard Ellis

Life on earth began in the sea, and in this tour de force of natural history, authority on marine biology and illustrator Richard Ellis chronicles more than three billion years of aquatic history. From the first microbes and jawless fishes that evolved into the myriad species we know today-sharks, whales, dolphins, and, of course, humans-Ellis reveals the deep evolutionary mysteries of the sea. Encyclopedic in scope and complemented by more than sixty drawings, Aquagenesis is a fascinating work that will astonish readers with the wonder, richness, and complexity of the evolution of life.

"Quite simply, the best account we now have of the origins of human life." (Te Christian Science Monitor)

Genres: Science, Nonfiction, Animals, History, Nature, Evolution, Biology

320 pages, Paperback

First published January 1, 2001

About the author

Richard Ellis is a celebrated authority on marine biology and America’s foremost marine life artist whose work has been exhibited worldwide. His nine books include The Search for the Giant Squid (a Publishers Weekly 1998 Best Book of the Year), Great White Shark, Encyclopedia of the Sea, Men and Whales, Monsters of the Sea, Deep Atlantic The Book of Whales, and Imagining Atlantis.

Reviews

[Diana · Rating 4 out of 5]

Aquagenesis: The Origin and Evolution of Life in the Sea [2001] – ★★★★

May be on an academic side and now a bit dated, but the book is still a perceptive and engaging account of the mysteries that still surround the evolution of life in the sea.

“That we live on land is, in the grander scheme of things, best regarded as an anomaly, or even an eccentricity – albeit with sound evolutionary justification. The story of life is, if we retain a true sense of proportion, a story of life at sea“(Philip Ball).

After I read Monarchs of the Sea by Danna Staaf last year, I wanted to read a deeper work on this topic and chose Aguagenesis by marine biologist Richard Ellis. The author aims to demonstrate how life originated in water some 3.9 billion years ago, what species evolved first in water and why, what species followed them and how evolution changed courses multiple times with various animals choosing to dwell on land next and then returning to waters. Richard Ellis starts his book by discussing the origin of water itself and a 2 inch-long shrimp-like creature without eyes capable of subsisting on hydrogen sulphide alone, which is poisonous to most living creatures, before talking about more complex and diverse marine life that roamed the oceans in the final stages of the Cretaceous period, some 65 million years ago. “More than 99% of all the species that have ever lived on Earth are [now] extinct” [Ellis, 2001: 22], says the author, and that makes that extinct life even more fascinating, especially in what it can tell us about the diversity of life and our own, human, origin.

Richard Ellis starts his story from the very beginning, speculating that life began in some “pitch-black, superheated, sulphide-rich environment without any connection whatsoever to sunlight” [Ellis, 2001: 11]. These conditions were not dissimilar to those found today in subterranean hydrothermal vents deep in the ocean. Ellis then discusses very primitive life forms that first emerged at that time. The period is called Ediacaran, and at the Burgess Shale, for example, evidence was found of ediacara biota. Such organisms encompass soft-bodied entities and fauna prevalent at that time and included dickinsonia, an organism that evolved 635 million years ago and which represents a symmetrical ribbed oval whose precise functions are still unknown; and cyclomedusa, a circular fossil. Ellis states that that “ediacarabiota populated the ocean up until the end of the Precambrian 535 million years ago, with the close of the Precambrian much of the ediacara biota became extinct” [2001: 31]. This period was before the “greatest evolutionary event in Earth’s history: the Cambrian explosion” [2001: 32].

When the “Cambrian explosion” happened some 541 million years ago, simple animals began to be succeeded by many complex ones, and, in that period, we start to see animals that had jaws, shells, limbs, bones and teeth. The author here asks some thought-provoking questions such as – will conscious life ever had a chance to appear if the ediacaran fauna not died out and prevailed? In the Cambrian period, first cephalopods, molluscs, crabs, nautiluses (or “living fossils”), trilobites and other ammonites appeared. There is still a debate why the “Cambrian explosion” of life occurred, and the most prevalent theory has to do with an increase in oxygen levels. Thus, first vertebrates appeared, but the precise origin of vertebrates is also shrouded in mystery [Ellis, 2001: 80]. In the Ordovician period, such creatures emerged as armoured Sacabambaspis or jawless fish, and first cephalochordates.

The Devonian period was an era of fish. “Fishes have been swimming on Earth for more than 450 million years. They predated the dinosaurs by hundreds of millions of years, and they were the first creatures to have an internal skeleton. In that sense, they are the ancestors of all vertebrates – amphibians, reptiles, birds, and mammals. Fishes are among the most successful animals ever” [Richard Ellis, 2001: 96]. The author states how the development of their jaws was a very important evolutionary advantage. Through their jaws, fish were able to prey on other species and the development of their “armour” helped them against predators. Dunkleosteus is probably best known armoured fish of the Devonian period and could reach the length of 9 metres. Here it was interesting to read about the discovery of bioluminescence in fish or its the ability “to glow” in the dark. Starfish, certain sharks and squid also have this ability. Some of them are able to glow because of the luminous bacteria that give off light. These bacteria cannot exist without its host [Ellis, 2001: 103]. The function of this light may include attracting mates, indicating sex or luring preys.

In the Permian period, some 298 million years ago, ancestors to many today’s sharks appeared and at least the very first “sharks” looked nothing like sharks today, the author says. For example, dental arrangements of these sharks sometimes appeared on their heads or backs [Ellis, 2001: 299]. For example, helicoprion was a shark who had a very unusual, spiral teeth arrangement embedded in the lower jaw. Precursors to amphibians also appeared, including labyrinthodonts, living some 359 – 251 million years ago. Another section of the book is titled “Return to the Sea Marine Reptiles” and here the author says: “reptiles evolved on land, but after their dispersal to various terrestrial habitats (becoming eventually either dinosaurs or lizards in the process), some returned to the sea” [2001: 260]. Thus, first sea turtles, snakes and crocodile ancestors are discussed. It was particularly interested to read that “crocodilians breezed through the cataclysmic K-T Extinction (66 million years ago), which eliminated some 70 percent of all living animals….but now face extinction threat from humans” [Ellis, 2001: 266]. Nowadays, Philippine crocodile and Siamese crocodile are some of the most endangered crocodiles on earth (there are about 250 endangered Siamese crocodiles left in Cambodia).

In discussing marine mammals (sea otters, seals, whales) and their antecedents, it was interesting to discover some puzzles in the evolution of whales. Ellis states that the oldest whale fossil dates to the Middle Eocene, 49 million years ago, but whales may have existed long before that date, and that present-day whales have probably evolved from such creatures as indohyus, a mouse-deer-like walking creature living some 40 million years ago and from mesonychus ambulocetus, living 55 million years ago in the Eocene epoch. The main question is, of course, why did early cetaceans take to water? This is still a mystery. The rest of this chapter talks about the mysteries of echolocation, biological sonar, especially in dolphins, why it evolved and what evolutionary paths might have led to it.

Fun begins when the author starts discussing speculations that the man might have had purely aquatic ancestors. In the 1970s-1980s, Elaine Morgan proposed a view, inspired by marine biologist Alister Hardy, that humans may be descendants from aquatic creatures because they are radically different from other mammals, for example, they display relative lack of body hair, have a power of speech and are bipedal like penguins. The theory is that “there was a period during which early hominids lived a semi-aquatic existence; they were never aquatic like cetaceans, but, rather, went in and out of the water frequently” [Ellis, 2001: 247, 267]. However, one question still remains: why certain mammals returned to the sea and others did not?

🌊 Aquagenesis is perhaps a book more on the evolution of sea life, rather than its origin, but the big plus of the book is that it does not dumb down its content like so many other non-fiction books do nowadays. Besides, it introduced me to many other related interesting books, such as to John Long’s The Rise of Fishes: 500 Million Years of Evolution, John McCosker’s Great White Shark, J.G.M. Thewissen’s The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea and to Richard Fortey’s Trilobite: Eyewitness to Evolution. Overall, Aquagenesis is a thought-provoking book which discusses one fascinating topic, inspiring you to know more.

[Jamie Smith · Rating 3 out of 5]

This is an odd book, halfway between popular science and academic exegesis. As popular science each chapter moves easily from the earliest creatures to either extinction or their modern variants, and points out the large gaps in the fossil record and the fact that in many cases scientists simply do not know the complete evolutionary sequence. As an academic study it is impressively documented, each page having multiple professional citations and even delving into the disagreements and controversies about how to interpret the evidence. I have an interest in etymologies, so I was happy to see the Latin and Greek scientific names translated into modern English.

The book has more of an encyclopedic approach than a narrative one. Whereas most popular science books would summarize the evidence for the reader, this book does so and then adds something different. In each chapter the narrative suddenly comes to a thudding halt and is replaced by page after page of morphological descriptions of various species. I could not understand the reason for this; for example, is it really necessary to give the reader detailed descriptions of every species of walrus and seal?

Nevertheless, some chapters are excellent. For instance, the one about the evolution of whales is illuminating and informative right up to the point where the author pauses the narrative for detailed descriptions of every major species. The 50 million year evolutionary path from a swift, medium size terrestrial carnivore to fully aquatic whales is one of evolution’s most fascinating and most mysterious stories. Transitional fossils have been found, but often there is only a single specimen to extrapolate from. One finding consists of only two partial leg bones, but since they were identified as whale-like, they were fitted into the sequence. The author does a good job pausing to let the reader think about the strangeness of the transformation, and the fact that none of the traditional answers to why the ancestors of whales returned to the seas, such as climate change or more food resources in the water, really hold up to the evidence. There are mysteries out there that we simply don’t know the answers to.

The book was published in 2001, so there are sure to be some parts that have been superseded by more recent scholarship, but I suspect the main themes are still scientifically accepted.

One of the book’s best features is the author’s offhanded way of tossing out facts and statistics, some of which sent me scurrying to the internet for more information. So, to finish off this review, I am going to include some of the ones that I found most interesting.

- Water is also the home of nine tenths of the Earth’s living things. Most of them breathe dissolved oxygen, not the oxygen in H2O. (p. 1)

- We are the only terrestrial mammals that hold our breath. We have proportionately as much subcutaneous fat as a dolphin. We can swim almost from birth. (p. 2)

- In any given population of animals (which [Darwin] recognized as a species), some of them naturally acquire modifications that make them a little better at making a living in their particular environment. If there is no change in that environment, there will be no noticeable change in the species. If, however, the environment changes even a little, as a result of say, a gradual change in temperature that affects the plant life, the animals must adjust this change, and those that have a modification that gives them a little edge will produce offspring that already have the advantageous modification. Those that – by chance – are not so advantaged will be unable to complete with the better-adapted, and will eventually die off. (p. 3)

- For more than 2.5 billion years in the history of life on Earth, all living things on Earth were under water. (p. 17)

- A recent estimate [of the amount of water on Earth] is 326 million cubic miles. (p. 20)

- For the nearly 4 billion years that preceded this mysterious and momentous event [the Cambrian Explosion], life had consisted of bacteria, multicelled algae, and single-celled plankton. Yet in the geological instant of 10 million years, the ancestors of all animals appeared. (p. 40)

- More than half of the known fossils from the Cambrian Period are trilobites, and they were the dominant life form on Earth for much of the 325 million years that we call the Paleozoic Era. (p.44)

- The eyes of trilobites differed in size, shape, and number of lenses, but they were all similar in one respect: they were made of calcium carbonate (CaCO3), a common, colorless mineral that is transparent in its purest form. (P. 49)

- Fishes have been swimming on Earth for more than 450 million years. They predated the dinosaurs by hundreds of millions of years, and they were the first creatures to have an internal skeleton. In that sense they are the ancestors of all vertebrates – amphibians, reptiles, birds, and mammals. (p.96)

- There are more than 24,000 species of bony fishes, compared to about 8,600 species of birds, 4,000 of mammals, 6,000 of reptiles, and almost 5,000 amphibians; clearly , fishes outnumber all other living vertebrates combined. (p. 100)

- Reptiles evolved on land, but after their dispersal to various terrestrial habitats, some returned to the sea. In geological time, this turnaround occurred soon after the conquest of the land. There are records of lizards knows as mesosaurs that had evidently achieved an aquatic existence as early as the Early Permian, almost 300 million years ago. (p. 140)

- [Antarctica’s] ice sheet represents 90 percent of the world’s ice and more than half of its fresh water. (p. 192)

- a large animal like a sperm whale needs 2,000 to 3,000 pounds of food a day to sustain itself (p. 232)

[Joanna · Rating 4 out of 5]

Not a bad way to close out this reading year. This is probably the hardest science book that I've read outside of a science class. The first hundred pages, in particular, were something of a slog. The book is meticulously referenced, which is academically sound, but makes for a more difficult reading experience as a typical sentence says, "As Smith and Wesson (1992) found, blah blah blah." For the first hundred or so pages, there's a meticulous description of all the prehistoric non-vertebrate sea life for which we have a fossil record. This is fascinating stuff in its own way, but was largely inaccessible to this non-biologist/paleontologist. When I was a college student, I briefly enrolled in a class called Biology of Fishes. The class was way over my head and I had to drop out, but I'm sure I would have learned stuff in that class that would have helped me interpret this book.

Once we moved on to vertebrates, I was more engaged and found the reading absolutely engrossing. By that point, I'd also become more accustomed tot he scientific references and felt more able to breeze through them.

I'd recommend this book, particularly if you can bring yourself to just skip the first section if you aren't tremendously interested in invertebrate fossils. But the description of the development of land animals (and then the return of land animals to the sea) is amazing. I was that annoying person who kept saying to my family, "Hey, did you know that whales are more closely related to elephants than fish?" and "Wow, there's a really interesting theory that humans have an aquatic or semi-aquatic ancestor that we haven't really discovered."

[Lynda · Rating 4 out of 5]

This is one of my favorite books. It explores how terrestrial animals migrated from land to the oceans and thrived. A whale is the decendent from a dog-like creature. Sea snakes, swimming birds and sea weasles are other creatures that are studied. Beautifully written, very entertaining.

[Alexandra Joy · Rating 3 out of 5]

Information overload, which is a good thing, but just a few factoids on what seems like every water-related species that ever lived. More images would have been nice, but descriptions were vivid.

[Tim Martin · Rating 4 out of 5]

Author Richard Ellis in _Aquagenesis_ originally sought out to document in a popular science format how the ancestors of marine mammals, reptiles, and birds returned to the sea. In the process of researching the book Ellis became intrigued with the phenomenon of life in the water, from the origin of life itself - which likely took place in water - to the evolution of marine invertebrates and fish. As result, the scope of the book widened considerably.

Ellis recounted some of the theories about the origin of life. The main one he reviewed was that life may have first appeared around hydrothermal vents in the deep sea, perhaps from impact generated hydrothermal systems (as for a period of about 200 million years, very roughly between 3.9 and 3.8 billion years ago, the Earth may have experienced as many as 10,000 impacts by extraterrestrial bodies). Not only would such environments have been plentiful, but they would have aided by virtue of high temperatures the creation of organic compounds and would have been places shielded from ultraviolet radiation.

I found fascinating his discussion of the Ediacaran (or Vendian) fauna, the oldest recorded animals, fossils of soft-bodied organisms that lived between 565 and 535 million years ago. The Ediacaran fauna is unusual; many of these organisms come in strange shapes and sizes, have no recognizable fronts, backs, heads, tails, circulatory, nervous, or digestive systems. Many of them vaguely resembled modern jellyfish, though they appear to have been benthic (or bottom-dwelling) organisms ranging in size from a few millimeters to a meter in diameter. One researcher (Gregory Retallack) according to Ellis believed that the Ediacarans were not soft-bodied animals at all but rather a type of lichen, with a sturdier structure made of substances not unlike chitin. Another paleontologist, Adolf Seilacher, wrote that the Ediacarans are unrelated to any existing lifeform (calling the Ediacarans as a group the vendozoans) and postulated that their structure was rather like that of an air mattress.

The much discussed Burgess Shale fauna is well covered in this book, along with the highly publicized disagreements between the late Stephen J. Gould, who felt the bizarre fauna represented many weird, wonderful, failed experiments, and Simon Conway Morris, who felt that researchers had focused too much on the differences rather than the similarities of the Burgess Shale animals to known species and phyla.

Ellis provided a good summary of squids, octopi, ammonites, belemnites, and the nautiloids (including the five existing species of nautilus), though much of his short section on trilobites quoted or paraphrased (with due credit) Richard Fortey's excellent book _Trilobite_. I think he could have been much more thorough though in his very brief discussion of the eurypterids (sea scorpions).

The evolution of fish is given wonderful treatment, accompanied by (as is much of the text) by Ellis' skillful black and white illustrations. I found his coverage of the coelacanths particularly interesting, noting some of the mysteries that even the living fish present (such as the function of their "rostral organ" - perhaps it is used to detect weak electrical fields). I also enjoyed his section on bioluminescence, something that still presents an enigma to biologists (such as how the luminous bacteria that some species depend upon to light up in the ocean depths are acquired, particularly if they cannot exist outside of their host and the young of the species are not born with the bacteria already present). Also worthwhile was Ellis' reporting of the Bear Gulch Limestone Formation of Montana (dating back to 320 million years ago from the Mississippian), a truly excellent fossil site that has yielded 4,500 specimens representing 113 species of fish, many beautifully preserved. A number of unusual fossils have been found there, such as the shark _Damocles serratus_, so named because of a dorsal spine with a serrated edge underneath, one that hung over the head of the animal, not unlike the sword that hung over the head of Damocles in ancient Greece.

Although not marine animals, the evolution of vertebrate limbs is covered as well. Ellis summarized the writings of Jenny Clack and others, noting the theory that the early amphibians used their legs not for terrestrial locomotion but for movement in the water or on river and lake bottoms, and that the study of the origin of tetrapods and the invasion of land by vertebrate animals are two issues that (according to researchers E. B. Daeschler and N. Shubin) need to be "decoupled."

Reptiles aren't given as much coverage as one might think. While sea snakes, crocodilians, and sea turtles are very well covered (the latter with a nice rundown of living species), the Mesozoic marine reptiles are given short shrift. Ellis has said in his subsequent book on Mesozoic marine reptiles, _Sea Dragons_ that he cut them out of _Aquagenesis_ due to space requirements.

The evolution of penguins and particularly marine mammals - sea otters, seals, walruses, whales, dolphins, porpoises, manatees, and dugongs - has some of the best coverage of any subject in the book. Particularly interesting were the problems with the pinnipeds (seals) in the fossil record, how they appear already to be fairly well specialized in the Miocene (about 24 million years ago), lacking much in the way of transitional forms; also the possibility of separate ancestors for the eared seals and walruses (perhaps a bearlike progenitor) and the earless seals (maybe an otterlike ancestor).

Near the end Ellis presented the controversial Aquatic Ape theory that humans descended from an ancestor that may have spent a fair amount of time in shallow coastal waters. Citing evidence presented by Alister Hardy and Elaine Morgan that man may have had an aquatic past - the presence of large amounts of subcutaneous fat, hairless bodies, the only terrestrial mammals that can hold their breath, that humans can swim almost from birth, noses well adapted to keep out water from nasal cavities - Ellis also recounted the opposition this theory has met.

Though I found a few errors in the book, overall it was enjoyable.

[Mike Parkes · Rating 3 out of 5]

For such a fascinating topic (the origin and evolution of marine animal life), this book was pretty dry and not as interesting as it could have been. It can be tricky going as there are many places where the text casually assumed a deeper level of knowledge regarding the variations in animal morphology and physiology than I possessed.

Although the ocean has a much wider variety of animals than the land (something like 34 phyla versus 15 on land), this book mostly (although not exclusively) deals with the better-known vertebrates. The most interesting chapter was the evolution of whales, which is covered in great detail.

[Emma · Rating 5 out of 5]

I was super duper excited to read this book and it was absolutely fascinating. I couldn't read the book in one sitting because I would get distracted picturing all of the organisms Ellis mentioned or drew. I loved this book nonetheless and if any of you are interested in fossils and the ocean, definitely read this book!

[Minister Jane Trivigno · Rating 4 out of 5]

pretty damn good book, went over the evolution of every animal group of the sea from the cambrian to today, and takes its time with its 260 pages. would’ve liked to see the chapter of the evolution of fish to be longer though.

[Johnny Altomonte · Rating 4 out of 5]

Incredibly comprehensive and encyclopedic read on marine life and its rich and twisted history. Every page is full of new information, which can be a bit much at times, but in the best way possible.

[Lara · Rating 4 out of 5]

A little slow at a few moments, but I actually found most of this book super fascinating, especially the parts about the Burgess Shale fossils and the evolution of whales and dolphins. And I really enjoyed the way that Ellis lays things out, starting with the oldest and smallest known organisms and working up to the whales. He explains things in a really interesting way as well; I'll definitely read more of his work!

[Thom Riddle · Rating 4 out of 5]

Amazing, have been reading alot of evolutionary writing lately. This has had to have been my favorite by far. From simple beginnings with interest in dinosaurs, space and ancient egypt, i have broadened my horizons to the point where this may well be my last book i read for a while before i slide into a realm of writing. Definitely recommended. Would almost give it five stars for content, but the writing style i found to be too colourless and stale.

[Rei ⭐ [TrulyBooked] · Rating 3 out of 5]

This is not the light-hearted romp that I thought it was going to be. Maybe I was lulled by the picture on the front, but I was not expecting something this dense. I wouldn't call it enjoyable, but it was really interesting at the same time. It has long dry spells, however, and I don't think I would read it again.

[Matthew · Rating 4 out of 5]

Although it can be a little dry and heavily laden with latin thanks to Linnaean classification, it is a compelling synopsis of the origin and radiation of life in the seas.

[Jasper · Rating 5 out of 5]

Starts w/ trilobites and ends w/ an aquatic theory of human evolution. Took me a little while to get through, but it was worth it.

[Jennifer Deascentis]

Trying to get back into read oceanography books - this has been on my book shelf for 5 years and I've never picked it up....

[Elizabeth]

As heard on the Science Times podcast.

[Uzma Aslam Khan · Rating 5 out of 5]

Love this book. Read it while doing research for my novel The Geometry of God, and found it hugely inspiring.

[Don · Rating 3 out of 5]

This book is a nice introduction to almost anything you'd find in the ocean, from the microscopic to whales and seals and sea-birds.

[Mander Pander]

If I'm honest, I'm just not cerebral enough to get my funs reading about the fossil record.

[Marina · Rating 3 out of 5]

A big lit review. Kinda dry.

[Emma · Rating 4 out of 5]

Intense lengthy book thoroughly analyzing sea creatures. Definitely not for everyone but a bastion of knowledge