Within each of the animal phyla the pelagic groups are identified and detailed coverage is provided for classification and history, internal and external anatomy, vertical and geographic distributions, locomotion and buoyancy, foraging strategies, feeding and digestion, bioluminescent systems and their function, reproduction and development, respiration, excretion, nervous systems, heart and circulation and all sensory mechanisms: vision, mechanoreception (touch, balance, and vibration) and chemoreception (smell and taste).
Life in the Open Ocean: The Biology of Pelagic Species is written so that it can be used as a textbook at the advanced undergraduate or graduate level of instruction, and as a reference for those interested in marine biology including professors, interested undergraduates, and perhaps for High School teachers teaching at the AP level. It is our fondest hope that it will make open‐ocean biology considerably more accessible, increasing its visibility and its presence in college‐level science curricula.
Joseph J. Torres
Thomas G. Bailey
Acknowledgments
Our heartfelt thanks to Dr. Dante Fenolio for the use of his fabulous images in Life in the Open Ocean: The Biology of Pelagic Species. They enabled us to show structures such as eyes, photophores, barbels and lures as well as whole animal appearance with freshly captured specimens, a boon for descriptions and a treat for the reader. As we progressed through the animal groups, specific questions arose that our longtime colleagues gave us help with. Advice on all things fish came from Dr. Tracey Sutton; questions on neurophysiology and bioluminescence were covered by Drs. Tamara Frank and Edie Widder; crustacean help came from Drs. Scott Burghart, Robin Ross, and Langdon Quetin; Claudia Mills gave us help with classification in cnidarians and ctenophores; and Eileen Hofmann and John Klinck helped with Antarctic physical oceanography. Special thanks to Bruce Robison and Alice Alldredge for the opportunity to dive WASP and Deep Rover many years ago. JJT would like to thank George Somero for a great sabbatical year and much biochemical advice over the years and Jim Childress for being the deep‐sea sage that he is. Many thanks to our friend Ms. Cynthia Brown who obtained many important publications for us as head of the interlibrary loan office at USF St. Petersburg.
Study of open‐ocean biology requires going to sea in ships, and running a trawling or diving program at sea requires a team. As one progresses from being a participant in early days to principal investigator, field‐team leader, and chief scientist, the teams change, as do the ships, the nets, and if you’re really lucky, the submersibles. But, also if you’re lucky, you get to keep a few colleagues for several years. Foremost among those for JJT was his longtime research associate Joe Donnelly, colleague over two decades, and his co‐principal investigator Dr. Tom Hopkins, peerless zooplankton biologist and expert on the zooplankton fauna in three oceanic systems. For TGB his tireless research associate and good friend Gary Owen as well the crews of the ships and Johnson‐Sea‐Link submersibles at the Harbor Branch Oceanographic Institution provided invaluable support throughout his research career. All our colleagues mentioned above were with us on multiple cruises as well. JJT would like to thank my many graduate students, most of whom went to sea with me several times, some to the Antarctic, some to the Gulf of Mexico, some to the Caribbean, and some to Cariaco Basin. All are remembered here, and the reader will see their names many times in the text. In several cases, we were one science party in a multidisciplinary science team, examples of which were the AMERIEZ program discussed in the text, and the Southern Ocean GLOBEC program. Lastly, all the science teams were aboard research vessels, and the captains and crews of those vessels, and in the Antarctic our science liaison officers, made everything possible. Thanks to all.
Lastly, the authors would like to thank the National Science Foundation and NOAA's National Undersea Research Program for funding our research over many years. Without their support, the research reported in here would have never happened, and not only ours but that of the multiple other labs whose research is cited in the book. Special recognition to Dr. G. Richard Harbison, exceptional gelatinous zooplankton biologist and never‐ending source of good humor who has crossed the rainbow bridge. We miss him.
1 Physics and the Physical Environment
For many beginning the study of oceanic fauna, the ocean itself is a fairly mysterious place. We know that it is vast, deeper in some places than others, and that the deep sea is cold and dark. What is less clear is how physical factors vary over the global ocean and why they are the way they are. The purpose of this first chapter is to briefly describe the physical factors impacting pelagic (open ocean) animal life and how those factors are distributed in the world ocean in the horizontal and vertical planes. Physical factors play an important role in shaping the adapted characteristics of animal life, particularly physiological characteristics, and by virtue of being physical factors they vary predictably in space and time.
One of the main purposes of this book is to give the reader an appreciation of pelagic communities, with as many of the players being treated as possible and with an accent on the community as a whole. Oceanic communities are constrained to water masses, identifiable (sometimes very large!) parcels of water, because the species comprising those communities live out their life histories in a discrete region and those regions have predictable characteristics to which life has become adapted. Adjacent oceanic regions that harbor fundamentally different communities presumably must differ enough physically and be separated enough from a biological perspective, that selection can change species composition. Physical factors play a big part in that selection process.
The physical factors limiting the distributions of open‐ocean species are temperature, oxygen, light, and pressure. Salinity, an important variable in estuarine systems, is of far less importance in the open ocean. Salinities in the open sea vary from approximately 33 parts per thousand (ppt or ‰, a 3.3% salt solution) to 38 ppt (a 3.8% solution), which is not a sufficient fluctuation to act as an important selective pressure on pelagic fauna. However, salinity does act indirectly to influence oceanic communities as it is an important operator in ocean circulation and the formation of water masses. And it does vary enough to be useful in identifying water masses when plotted against temperature in a T‐S diagram, discussed later in this chapter.
An individual animal’s interactions with the open‐ocean environment are governed not only by temperature and pressure but also by the properties of water as a fluid. How fast a shark sinks relative to a jellyfish is within the province of basic fluid dynamics, as are the forces acting on the swimming individuals as they make their way quickly or slowly through the fluid medium.
Since the distribution and characteristics of oceanic life are dictated partly by the characteristics of the physical environment, it is imperative that one have a fundamental understanding of how that environment varies with location and of some of the principles that govern the variability. This chapter will cover enough of the basics to provide an understanding of the physical environment of the open sea and the biological interaction with it.
The Vastness of the Open Ocean
A few facts about the open ocean are important to help put the vastness of the oceans in perspective. To appreciate the total living space available to pelagic fauna, we need to consider both the ocean’s surface area and the volume beneath the surface: the ocean’s horizontal and vertical extent. The ocean basins cover 71% of the planet and their average depth is 3800 m (Sverdrup et al. 1942). Since the Earth is a sphere with a radius of 6371 km, its total surface area is calculated at 5.1 × 108 km2. The surface area of the world’s oceans at 3.6 × 108 km2 is ~71% of the total surface area of our planet. Consider volume. The average
