The Anatomical Record Returns to the Sea: Exploring the Great Whales and Their Interesting Relatives.

Abstract

The two authors of this editorial adore whales. We have often gone to the open sea to explore them, sometimes together, but from different perspectives. KA is always ready with an array of multilensed cameras, hanging off the side-rails of the ship, and capturing the sprays and breeches of the whales; JL can also usually be found hugging the side-rail, frequently returning his breakfast to the sea. (KA is also fond of filming JL, and emitting the classic call of the sea, “thar she blows,” albeit “blow” having a decidedly different meaning from that usually uttered by seafaring folk!) Our differing vantage points notwithstanding, we, like so many others, adore our large, watery, mammalian kin. Our fascination with them is multidimensional, attracted by the fact that they are the most mysterious mammals due to their habitat, by their extraordinary evolutionary path and unique adaptations, and by the realization that they are among the smartest of all our relatives. The fascination between humans and whales goes back a long, long way, arguably to stories of Jonah and the great leviathans. For those of you not smitten with the love of whales, a little primer can help. There are two living types of whales, those with teeth (toothed whales or odontocetes, including the familiar dolphins and porpoises) and those sans teeth but with baleen plates (mysticetes) used to filter-feed the krill they eat. These are both usually grouped in the infraorder Cetacea with Odontoceti and Mysticeti being the parvorders (suborders). The living families are thought to have derived from a paraphyletic group of primitive cetaceans collectively usually called Archaeoceti, who lived some 55 to 23 million years ago. Going back even further, all whales are thought to have derived from even-toed ungulates (Artiodactyla) and due to this, modern taxonomic classification often emphasizes the relationship between whales and artiodactyls by identifying them all in the superorder Cetartiodactyla (see Marquez et al., 2019, this issue; Maust-Mohl, 2019, this issue). So, simply put, Flipper and Moby are related to Bullwinkle, hippos, and bison. Got it? (Quiz at 3.) Of the two types of whales—odontocetes and mysticetes—we have collectively learned a lot more about those with teeth. They are relatively smaller than the mysticetes (although some, such as the sperm whale, can grow to 60 ft in length! Melville's Moby Dick was one of these) and at times live nearer the shores and accessible inlets. Dolphins and porpoises are toothed whales, and their accessibility and involvement in scientific studies has allowed considerable insight into their worlds. Mysticetes, on the other hand, are usually much less accessible, and their often gargantuan size has precluded ease of interaction. This group comprises the great leviathans, blue whales, fin whales, right whales, humpback whales, and gray whales of the oceans that regularly grow well in excess of 50 ft in length (and some, such as blue or fin whales, to 90 ft!). What their world is like, how they communicate, their mechanisms for rapidly diving to extraordinary depths, their reproductive biology, and so on, remain largely unknown. Unknown, but alluring and fascinating, which brings us to this Thematic Papers Issue: “Mysticete Anatomy and Evolution,” edited by our favorite whale aficionado, Joy Reidenberg, of the Icahn School of Medicine at Mount Sinai (Reidenberg, 2019, this volume). This issue arose out of a unique experience at Mount Sinai, a “Mysticete Mini-Conference,” wherein some 50 whale scientists, comparative anatomists, brain experts, and upper and lower respiratory system biologists came together for 2 days of discussion coupled with a unique opportunity to dissect a treasure trove of mysticete, moose, and hippo materials (remember, these are all relatives) that were part of the collections at Mount Sinai that Joy had obtained over the years. While most participants were from the northeast United States, colleagues from as far away as France and Madagascar also participated. The Conference, supported in part by Mount Sinai's Center for Anatomy and Functional Morphology and The Anatomical Record, included both presentation of podium papers and the opportunity to all those present to meet the insides of those discussed firsthand. The hope was that new understandings of the elusive world of mysticetes would emerge. As noted, The Anatomical Record has a long and robust history of enlisting and advancing studies on the biology, evolution, and anatomy of whales. To recount all of these would require a whale of a book in itself, so we will note only a few here, particularly three Special and Thematic Issues of recent vintage. Dr. Reidenberg mentioned above oversaw the first such issue in 2007 (Laitman, 2007; Laitman and Albertine, 2007; Reidenberg, 2007). As noted, Joy (and we know her too well to be formal) is our favorite cetacean guru, having published her research extensively in The Anatomical Record, often with her trusty coworker, JL, at her side. Indeed, her research has encompassed a vast panoply of toothed and baleen whales and has graciously flooded our pages (e.g., Reidenberg and Laitman, 1987, 1988, 1994, 2007a, 2007b, 2008; Cooper et al., 2007; MacLeod et al., 2007; Berta et al., 2015; Keinle et al., 2015; Damien et al., 2019, this issue; Maust-Mohl, 2019, this issue; and Raghanti et al., 2019, this issue). Our whale advocate and promoter is quite a character, and has been the cause of great “joy” for our journal and, at times, also great pain for JL, her graduate advisor and long-time (and often long-suffering) coworker. The pleasure is obvious as she has swum to the head of the pod and become one of the world's experts on the head and neck of both toothed and baleen whales. JL's pain has come from his having to accommodate the trove of watery friends that she has brought to reside in freezers at Mount Sinai. There are two telephone calls that JL has learned to fear over the years: the first is hearing, “the Dean wants to see you” (think budget being slashed!); the second is from the said whale woman, “I'm at a stranding and bringing home …” Do you know how difficult it is to bring a whale, or large portion of such, into a NYC hospital? During the day? With lots of people around? And then fit a 12-ft whale into an 8-ft freezer? Let us just say that all those wonderful manuscripts have cost JL many a pro bono lecture and lost weekend in “paybacks” for building “Joy's whale world” in part of our school of medicine. Our first large foray into reporting whale biology was in Joy's 2007 Special Issue, “Anatomical Adaptations of Aquatic Mammals.” This issue highlighted work by some of the leading aquatic mammal researchers of our time, to mention but a few: Uhlen's (2007) detailed review on the evolution of marine mammals; Fish, Benesky, and Ketten's study of the 3D geometry of cetacean flukes using CT scans (2007); Jim Mead's detailed study on the stomach anatomy of beaked whales (2007; Jim is a most beloved Curator Emeritus of the National Museum of Natural History in Washington and besides his own insightful work has helped foster the careers of countless comparative anatomists, including Joy and JL); Werth's insightful study on the cetacean hyolingual apparatus for aquatic feeding and thermoregulation (2007); Cooper and colleagues' study of digit reduction in the manus of cetaceans (2007); Marino's thought-provoking review on cetacean brains (2007); Nummela and colleagues' exploration of sound transmission and hearing in archaic and living whales (2007); and Parks and colleagues' anatomical predictions on the hearing of North Atlantic Right Whales (2007). These are just some of the insightful papers in this now classic Special Issue. A fortuitous mix of ready scientists being in the right place at the right time led to our next issue. A gray whale calf stranded on a California beach and, as it was deemed not viable if returned to the sea, was euthanized. Serendipitously, the American Association of Anatomists, the parent body for The Anatomical Record, was anatomizing at our annual meeting down the road in San Diego. Thanks largely to the fast action and organization by Erik Ekdale and colleagues of San Diego State University, an energetic posse of anatomists fled the halls of the convention center to dissect and study the rare specimen. The resulting observations were recorded in a beautiful thematic issue edited by Ekdale entitled, “Thematic Papers: Anatomical investigations of the California gray whale” (Berta et al., 2015; Laitman, 2015; Laitman and Albertine, 2015). The issue concentrated on the head and neck anatomy of the specimen, bringing forward at times unknown or unrecognized aspects of the species anatomy, often in a comparative context. The papers included are as follows: Berta and colleagues' observations on features of the head and neck, particularly in reference to thermoregulatory and feeding abilities (Berta et al., 2015a) and their observations on aspects of the eyes, nose, hair, and throat (Berta et al., 2015b); Kienle and colleagues' observations on the tongue and hyoid musculature (Kienle et al., 2015); Ekdale and Kienle's (2015) study of the anatomy of the lingual retia and its relationship to blood flow and heat exchange; El Adli and Demere's observations on the structure and muscles of the temporomandibular joint (2015); Ekdale and colleagues' observations and assessments of vascularization of the Gray Whale palate (2015); and Young et al.'s (2015) study of the morphometrics and structure of the baleen. Our most recent encounter with whales was made possible by another fortuitous event, namely, our Anatomical Record Editorial Board Meeting taking place in incomparable Vancouver, British Columbia, Canada. The world of this northwest wonderland is replete with wildlife, including within the sea. We took advantage of this to press into service Professor Wayne Vogl of the University of British Columbia, an always-proud son of Canada, eh, to put together a Thematic Papers issue reflecting the beauty that we had experienced. The resulting compilation was the Thematic Papers Issue on “North American Pacific Coastal Whales,” which, due to his always meticulous efforts, did so swimmingly (Albertine et al., 2017; Vogl, 2017). This small issue had four excellent manuscripts that advanced new thoughts and findings on whales of the region, many of which said hello to us (and vice versa) during our visit. The papers included are the report by Goldbogen et al. (2017) describing the use of tags with an integrated video to study the moving morphology of large aquatic vertebrates; Jensen and colleagues' study on the comparative 3D morphology of baleen (2017); Shadwick and colleagues' report on the structure and function of the lunge-feeding apparatus in fin whales; and Vogl and colleagues' most interesting study of the functional anatomy of innervation of the ventral grooved blubber of fin whales (2017). President Kennedy had on his White House desk a small plaque engraved with an old Breton fisherman payer: “Oh, God, thy sea is so great and my boat is so small.” It was given to him by Admiral Hyman Rickover, founder of our nuclear submarine navy. As a navy man, the plaque, and its meaning, meant a great deal to Kennedy as he saw it daily and referred to its message often. In writing this piece, we thought back on the plaque (which we both saw during our visit to the Kennedy Presidential Library a few years back). While it obviously speaks to the reverence of a fisherman for the greatness of the sea, it is, of course, a metaphor for how small we are in comparison to the world around us. In writing this editorial about the largest animals on our planet, some, the largest that may have ever lived, we are reminded that they too, great and magnificent as nature has made them, are but fragile beings within a vast and overpowering sea. Our world is more fragile than many realize, and while some may choose to ignore data and the warnings of climate change with the inevitable altering of our planet, the threats are here and real. Within this context, we must realize that many of the wonderful and wondrous animals whose anatomy is described herein are as small and fragile as the lone fisherman in his little boat. Many are already on endangered lists, and it is always a battle to keep others off. We must not be fooled by their size; they are fragile and susceptible to even the slightest changes in their world. Fig. Characteristic heart-shaped blast of exhaled, moist air from the pair of blowholes on top of the head of baleen whales, such as this California gray whale. The heart-shaped mist from two blowholes coalesce into this shape when the weather is not windy. Photo by KH Albertine