15: The Living Sea
- Page ID
- 31584
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)If anything draws people to the sea—to walk beside its shores, ride along its surface, or plunge into its depths—surely it must be the otherworldly creatures that dwell within it. Part enchanting, part terrifying, the living sea offers an extraterrestrial world on our own planet. Sir Arthur Clarke (1917–2008), creator of numerous fictional extraterrestrial worlds and an avid scuba diver, opined, “No beings from outer space could be more weird than some of the plants and animals that inhabit the oceans of our own world” (Clarke 1960). Indeed, the more we poke, prod, and explore, the weirder the ocean seems: 440-pound jellies with deadly venom, crabs that gather on boiling vents, sea lions that herd oceanic tuna, and octopuses that become friends with humans.
With much of the ocean unexplored—especially midwater and abyssal regions—it should come as no surprise that we continue to make new discoveries on every expedition. Yet in recent decades oceanographers haven’t had to travel too far to make the most startling of discoveries. By probing the genetic makeup of the “invisible” life-forms in seawater—the microbes—a world beyond our imagination has been discovered. Microbes trade molecules, team up to work, sport enormous metabolic toolboxes, thrive everywhere, and are possibly more diverse than all other marine life-forms combined. What’s more, a good percentage of them are completely new to science, life-forms only recently discovered in the ocean. Our newfound understanding of the importance of viruses in the ocean, our increased recognition of the role of diverse feeding modes, and an emerging perspective of the ocean as a microbial network that responds holistically to changes in the environment—a microbial interactome—have radically changed our view of the ocean in just a few decades.
In the chapters that follow, we explore the living sea, the interconnected, self-replicating, and self-sustaining network of diverse life-forms that inhabit the world ocean. Arguably, the living sea constitutes the most important part of Earth’s biosphere, dominating cycles of carbon, nitrogen, and oxygen. And while it may or may not be as diverse as the terrestrial biosphere—the question remains unsettled—it certainly is the most ancient biological system on our planet. The present-day inhabitants of the ocean and the roles they play in the modern living sea emerge from their evolution over billions of years. We’ll get to that history in a bit. But first we must try to make some sense of the living world, bring some order to the living sea so that we may better appreciate their diversity and function.