(Ebook) Cambridge IGCSE and O Level History Workbook 2C - Depth Study: the United States, 1919-41 2nd Edition by Benjamin Harrison ISBN 9781398375147, 9781398375048, 1398375144, 1398375047
Annalisa Berta has been Professor of Biology at San Diego State University, California, for more than 30 years specializing in the anatomy and evolutionary biology of marine mammals. Past President of the Society of Vertebrate Paleontology and co-Senior Editor of the JournalofVertebratePaleontology, Berta has authored and co-authored numerous scientific articles and several books.
Portions of this work were written and prepared by officers and/or employees of the U S Government as part of their official duties and are not copyrightable
Library of Congress Cataloging-in-Publication Data
Berta, Annalisa, author
Whales, dolphins, and porpoises : a natural history and species guide / Annalisa Berta pages cm
Includes bibliographical references and index
ISBN 978-0-226-18319-0 (cloth : alk paper)
ISBN 978-0-226-18322-0 (ebook) 1 Whales Anatomy. 2 Dolphins Anatomy. 3 Porpoises Anatomy 4 Whales Behavior 5 Dolphins Behavior 6 Porpoises Behavior I Title QL737 C4B6515 2015 599 5 dc23 2015008715
This paper meets the requirements of ANSI/NISO Z39 48-1992 (Permanence of Paper)
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WHALES, DOLPHINS & PORPOISES
A NATURAL HISTORY AND SPECIES GUIDE
THE UNIVERSITY OF CHICAGO PRESS Chicago
The eighty-nine cetacean species that swim our seas and rivers are as diverse as they are intelligent and elusive, from the hundred-foot-long, two-hundred-ton blue whale to the lesser-known tucuxi, ginkgo-toothed beaked whale, and diminutive, critically endangered vaquita. The huge distances these highly migratory creatures cover and the depths they dive mean we catch only the merest glimpses of their lives as they break the surface of the water But thanks to the marriage of science and technology, we are now beginning to understand their anatomy, complex social structures, extraordinary communication abilities, and behavioral patterns. In this beautifully illustrated guide, renowned marine mammalogist Annalisa Berta draws on the contributions of a pod of fellow whale biologists to present the most comprehensive, authoritative overview ever published of these remarkable aquatic mammals.
CONTENTS
Introduction
The Biology
Phylogeny & Evolution
Anatomy & Physiology
Behavior
Food & Foraging
Life History
Range
Habitat
Conservation & Management
Identification Tools & Maps
Identification Keys
Surface Behaviors
How & Where To Watch
The Species Directory
How to Use the Species Directory
Right Whales
Southern Right Whale
North Atlantic Right Whale
North Pacific Right Whale
Bowhead Whale
Pygmy Right Whale
Rorqual Whales & Gray Whale
Gray Whale
Common Minke Whale
Antarctic Minke Whale
Sei Whale
Bryde’s Whale
Blue Whale
Omura’s Whale
Fin Whale
Humpback Whale
Oceanic Dolphins
Commerson’s Dolphin
Chilean Dolphin
Heaviside’s Dolphin
Hector’s Dolphin
Long-Beaked Common Dolphin
Short-Beaked Common Dolphin
Pygmy Killer Whale
Short-Finned Pilot Whale
Long-Finned Pilot Whale
Risso’s Dolphin
Fraser’s Dolphin
Atlantic White-Sided Dolphin
White-Beaked Dolphin
Peale’s Dolphin
Hourglass Dolphin
Pacific White-Sided Dolphin
Dusky Dolphin
Northern Right Whale Dolphin
Southern Right Whale Dolphin
Irrawaddy Dolphin
Australian Snubfin Dolphin
Killer Whale
Melon-Headed Whale
False Killer Whale
Tucuxi
Guiana Dolphin
Indo-Pacific Humpback Dolphin
Indian Humpback Dolphin
Australian Humpback Dolphin
Atlantic Humpback Dolphin
Pantropical Spotted Dolphin
Clymene Dolphin
Striped Dolphin
Atlantic Spotted Dolphin
Spinner Dolphin
Rough-Toothed Dolphin
Indo-Pacific Bottlenose Dolphin
Common Bottlenose Dolphin
Sperm Whales
Sperm Whale
Pygmy Sperm Whale
Dwarf Sperm Whale
Narwhal & Beluga
Narwhal
Beluga
Beaked Whales
Arnoux’s Beaked Whale
Baird’s Beaked Whale
Northern Bottlenose Whale
Southern Bottlenose Whale
Longman’s Beaked Whale
Sowerby’s Beaked Whale
Andrews’ Beaked Whale
Hubbs’ Beaked Whale
Blainville’s Beaked Whale
Gervais’ Beaked Whale
Ginkgo-Toothed Beaked Whale
Gray’s Beaked Whale
Hector’s Beaked Whale
Deraniyagala’s Beaked Whale
Strap-Toothed Whale
True’s Beaked Whale
Perrin’s Beaked Whale
Pygmy Beaked Whale
Stejneger’s Beaked Whale
Spade-Toothed Beaked Whale
Shepherd’s Beaked Whale
Cuvier’s Beaked Whale
River Dolphins
Baiji
Franciscana
Amazon River Dolphin
Ganges River Dolphin
Porpoises
Narrow-Ridged Finless Porpoise
Indo-Pacific Finless Porpoise
Spectacled Porpoise
Harbor Porpoise
Vaquita
Burmeister’s Porpoise
Dall’s Porpoise
Appendices
Classification of Cetaceans
Glossary
Resources
Notes on Contributors
Index
Acknowledgments
INTRODUCTION
Whales, dolphins, and porpoises, also known as cetaceans, include 90 currently recognized living species. Although some cetacean species are on the brink of extinction, there are also exciting discoveries of new species. This guide is intended to introduce the reader to the identification and biology of these magnificent and charismatic mammals of the sea
Part One of this guide includes information about cetacean biology. The Phylogeny & Evolution section highlights where whales originated and how they evolved and diversified from the tropics to polar waters. The Anatomy & Physiology section includes key features of the head, body, and appendages (fins, flippers, and flukes) that enable a fully aquatic life emphasizing a few novel adaptations, such as highfrequency sound production and reception in some whales. These adaptations provide a historical framework for understanding how these mammals make a living today and guide our efforts in their conservation. The Behavior section highlights the social organization of cetaceans ranging from solitary species to the highly complex societies of some toothed whales. Cetaceans have evolved to feed on a diverse prey. Whales feed on aggregations of zooplankton averaging less than an inch (1-2 mm) in length to large squid 10 ft (3 m) or more in length. The section on Food & Foraging identifies how whales locate and catch their prey using techniques that range from the pursuit of individual fish to bulk feeding of large aggregations of zooplankton. The Life History section highlights the growth, reproduction, and survival of cetaceans including techniques for determining the age of whales. The reproductive biology of cetaceans reveals that many species do not reproduce annually, which is a key factor guiding our conservation efforts The Range & Habitat sections reveal how new techniques such as digital devices and satellite telemetry track the location, movement patterns, and ranges of cetaceans. The Conservation & Management section discusses the status of some endangered species, major threats, and notable conservation actions designed to protect cetacean species.
Part Two of this guide includes Identification Tools & Maps, which provides keys to the identification of whales, dolphins, and porpoises using distinctive body features such as size, color, and markings, and fluke and flipper shapes. There are many ways to watch cetaceans from the air, on land, and at sea. Many display distinctive surface behaviors described in this section such as leaping out of the water, which aids in their identification. Another section describes whale watching, which brings people in close contact with whales, covering the gear involved as well as some top viewing locations around the world Checklists provide species assemblages encountered in different regions of the world.
The largest section of this guide, Part Three, is the Species Directory (see here). This is followed by several appendices including a classification of cetaceans list, glossary of commonly used terms, and an index. We hope that you are inspired to find, recognize, watch, and appreciate whales, dolphins, and porpoises. Their future and ultimately our own depends on our abilities and efforts to conserve and protect the world’s oceans and its inhabitants.
Gregariousness
Groups of common bottlenose dolphins often travel together exhibiting playful behavior.
Breaching
This image shows a humpback whale displaying a typical “breaching” behavior in which whales, dolphins, and some porpoises leap out of the water. There are a number of possible explanations for this behavior including signaling, dominance, or warning other whales of danger.
THE BIOLOGY
Phylogeny & Evolution
The majority of marine mammals belong to the order Cetacea, which includes whales, dolphins, and porpoises. The name Cetacea comes from the Greek ketos meaning whale. Two major groups of extant whales are recognized toothed whales (Odontoceti) and baleen whales (Mysticeti) Toothed whales are much more diverse with 10 families, 34 genera, and 76 extant species (one of which is likely extinct) compared to mysticetes that include 4 families, 6 genera, and 14 extant species. Toothed cetaceans include sperm whales, oceanic whales, river dolphins, monodontids (beluga and narwhal), ocean dolphins, and porpoises. Baleen whales include the right whales, pygmy right whale, gray whale, and blue, fin, sei, Bryde’s, humpback, minke, Antarctic minke, and the recently described Omura’s whale.
Evolutionary relationships of whales
Cetaceans originated from land mammals and there is strong support for whales being most closely related to artiodactyls (even-toed ungulates), which include cows, goats, camels, and hippos. Because cetaceans and artiodactyls are linked, they are grouped together in the clade Cetartiodactyla. Within cetaceans, relationships among families are still debated. There is general agreement from both molecular and anatomical data for the family level evolutionary history among odontocetes. Basal odontocetes include sperm whales (Physeteridae and Kogiidae). Asiatic river dolphins, Platanistidae, are the next diverging lineage followed by beaked whales (Ziphiidae), Chinese river dolphin (Lipotidae), South American river dolphins (Iniidae and Pontoporiidae), and the latest most recent divergent lineage the Monodontoidea beluga and narwhal (Monodontidae) and porpoises (Phocoenidae), and oceanic dolphins (Delphinidae).
Unlike odontocetes, higher-level relationships among mysticetes conflict based on molecular (i.e. DNA sequences) versus anatomical data. Using molecular data right whales and the bowhead (Balaenidae) are recognized as basal mysticetes whereas anatomical data positions pygmy right whales (Neobalaenidae) as sister to Balaenidae followed by an alliance of the remaining baleen whales: rorquals (Balaenopteridae) and gray whales (Eschrichtiidae). The position of the gray whale is also debated.
Anatomical data places Eschrichtiidae and Balaenopteridae as close relatives whereas molecular data nests gray whales within balaenopterids.
Toothed whale (odontocete) phylogeny
Toothed whales
Evolutionary relationships among extant families of odontocetes based on anatomical data.
Whale origins
Cetaceans are first found in the fossil record approximately 52 5 million years ago (MYA) during the early Eocene period in current-day India and Pakistan. Recent discoveries in Pakistan and southern India have suggested that extinct artiodactyls, the raoellids, such as Indohyus, are the closet extinct relatives of whales. Indohyus was a cat-sized animal with a long nose, tail, and slender limbs. At the end of each limb were four to five toes that ended in hooves, similar to those of deer. Raoellids also had very thick dense limb bones, an adaptation for buoyancy control. Since raoellids were largely aquatic, this indicates that an aquatic lifestyle arose before whales evolved.
Whale relatives
Life restoration of the closest whale relative, the aquatic, deer-like raoellid Indohyus
phylogeny
Baleen whales
Evolutionary relationships among extant families of mysticetes based on molecular data.
Early whales had legs
The earliest stem cetaceans such as Pakicetidae (e.g. Pakicetus), Ambulocetidae (e.g. Ambulocetus), and Remingtonocetidae (e.g. Kutchicetus) are all known from the early and middle Eocene (50 MYA) of current-day India and Pakistan. They are all
Baleen whale (mysticete)
thought to have been semiaquatic, able to move on land as well as in the water. These stem whales had well-developed forelimbs and hind limbs. Wear on the teeth is consistent with a fish-eating habit. The occurrence of later diverging whales (such as Protocetidae, e.g. Rodhocetus), in Asia, Africa, Europe, and North America) indicates that cetaceans had spread across the globe between 49–42 MYA. They differed from other early cetaceans in having large eyes with the nasal opening that had migrated further back on the skull. Basilosaurids (such as Dorudon) the closest relatives of modern cetaceans were widely distributed and lived between 41–35 MYA Best known is Basilosaurus isis, which had a snake-like body with a maximum length of 56 ft (17 m), with several hundred skeletons reported from the middle-Eocene Valley of Whales in north-central Egypt.
Fossil whales and their closest relative
Fossil whales
This diagram shows the time ranges ofsome fossilandextantlineages ofwhales.
Modern whales
Modern (crown) cetaceans originated from archaic (stem) cetaceans, such as Basilosaurus, approximately 33.7 MYA during the Oligocene period. The diversification of modern cetaceans (Neoceti) has been associated with the breakup of the southern continents and restructuring of ocean circulation patterns signaled by higher oxygen isotope levels which resulted in increased food production (indicated by diatoms, a type of tiny algae) and upwelling of nutrient-rich water.
Crown cetaceans differ from stem cetaceans in having a telescoped skull. In “telescoping” the bones of the rostrum are extended and displaced posteriorly and the nostrils have moved to the top of the head where they form the blowholes (see here).
Odontocetes differ from mysticetes by the presence of teeth. Odontocetes acquired echolocation, which enabled them to produce high-frequency sounds that are reflected from objects that surround them these reflections allow them to pursue individual prey items. Mysticetes acquired a novel feeding mechanism, bulk filterfeeding using baleen plates, strainers in the mouth.
Although most whales today are entirely marine, early fossil members of this lineage, such as pakicetids, likely foraged exclusively in freshwater based on analysis of the carbon and oxygen isotope levels of their teeth and bones
Whale diversification
Diversity, food, and ocean temperature
Whale diversity is linkedto an increase in foodproduction driven by climatic changes(suchas ocean temperature). Differences in oxygen isotope values revealtemperature changes in thegeologicpast.
The oldest named odontocetes are from the North Atlantic (North America). A recently discovered stem odontocete, Cotylocara, has dense bones and air sinuses, features that support the theory that echolocation originated early between 32–35 MYA. Crown odontocetes, or modern families, diversified in the Miocene, approximately 23–26 MYA. Extant genera of both mysticetes and odontocetes appeared during the Pleistocene, approximately 1 6 MYA Analysis of the morphology and evolutionary
relationships of river dolphins supports the hypothesis that marine odontocetes invaded river systems on multiple occasions. The range and habitat of some whales is much different today than in the past. For example, distant relatives of the South American La Plata River dolphin had a broader range in the past that included southern California. A similar range expansion is indicated for fossil relatives of the beluga that today occupies Arctic waters but inhabited temperate waters as far south as Baja California in the Miocene.
Several fossil odontocetes exhibit unique feeding adaptations An extinct relative of monodontids (narwhal and beluga), Odobenocetops lived in Peru during the early Pliocene (3–4 MYA). The presence of tusks and a presumed mollusk-eating suction feeding habit are convergences (similarities based on ecology rather than relationship) with the walrus. A recently described fossil porpoise, Semirostrum ceruttii from the Pliocene of California is reconstructed to have employed a form of benthic skimfeeding by using its lower jaw, which extended further beyond the rostrum than in any other known mammal, to probe for and obtain prey.
Feeding specializations
An extinctfossilrelative ofthe beluga andnarwhal, Odobenocetops spp (see here)hadlarge, downturnedtusks anda bluntsnout Strong muscle scars atthe frontofthe rostrum, a vaultedpalate, and absence ofteethsuggests thatthey fedon benthic mollusks using suction. The extinctskimmer porpoise, Semirostrum ceruttii (see here), hadan elongatedlowerjaw extending wellbeyondthe rostrum thatitmay have usedtoprobe or skim along the seafloor forprey.
Odobenocetops
Fossil baleen whales
The stem whale, Aetiocetus weltoni, thatlived24–28MYA may have been the earliestbulkfilter-feeder employing bothteethandbaleen inprey capture. The fossilwhale species, Herpetocetus morrowi, describedfrom southern California is one ofthe smallestbaleen whales witha lengthof14¾ft(4.75 m).
Semirostrum
Aetiocetus
Herpetocetus
The earliest named mysticetes are from the South Pacific (Australia and New Zealand). These stem mysticetes, some of which were of large size ranging from 16–40 ft (5–12 m) such as Llanocetus, possessed well-developed teeth with multiple accessory cusps and likely hunted individual prey. Other fossil taxa, such as the Aetiocetus weltoni, were smaller-bodied and may have had both teeth and baleen employed in batch filter-feeding as seen in modern baleen whales.
The earliest known and earliest diverging toothless fossil mysticetes, the eomysticetids, were relatively large bodied at around 33 ft (10 m) in length, with long skulls. They appeared in the Oligocene in both the North and South Pacific and were contemporaneous with some stem-toothed mysticetes. Although the ancestral feeding strategy among crown mysticetes is debated, functional analysis of the late Pliocene (2.5–3.5 MYA) mysticete, Herpetocetus morrowi, suggests a lateral suction-feeding strategy similar to but evolved independently from feeding in living gray whales. As was the case for odontocetes, crown mysticetes underwent an explosive radiation in the Miocene. Whale diversity peaked in the late middle Miocene (14 MYA) and fell thereafter, yielding a modern fauna that is much less diverse today than in the past.
Anatomy & Physiology
Cetaceans display considerable diversity in size. Included among the mysticetes or baleen whales are some of the largest species such as the blue whale, the largest animal on earth at 110 ft (33 m) long and weighing 330,000 lb (150,000 kg).
Odontocetes show a wider range of sizes, from the sperm whale that is as large as some baleen whales to the vaquita that is about 4¾ ft (1.4 m) in length, weighing 92 lb (42 kg). In odontocetes or toothed whales, males are typically larger, whereas in mysticetes, females are generally larger than males. Since most mysticetes depend upon stored body fat to support their metabolic requirements, particularly during the winter months far from feeding grounds, the extra weight is necessary for their survival, promoting greater reproductive success and aiding females in the nursing of their offspring.
Adaptations
Cetaceans exhibit numerous adaptations for a fully aquatic life. Breathing occurs through blowholes that have migrated to the top of the head. Odontocetes have only a single blowhole instead of the two blowholes of mysticetes. The heads of mysticetes are very large, up to one-third of the body length.
The vertebral region does not contain a sacral region in whales because the pelvic girdle is absent. External hind limbs are very reduced or absent in cetaceans and the forelimbs have been modified into flippers or pectoral fins with an inflexible elbow that functions in steering. The broad flippers of some mysticetes, such as right and bowhead whales, aid in slow turns. The flippers of the humpback are exceptionally long and maintain hydrodynamic efficiency; they are also “waved” during feeding and social displays. The flippers of most odontocetes assist in turning during high-speed maneuvers while chasing prey. In odontocetes that occupy pack ice or rivers, such as the beluga or river dolphins, flipper shapes allow for angled maneuvers in those environments.
Size comparison among whales
Body sizes
Cetaceans differ considerably in their size Their size categories compared to a human for scale include: small, up to 10 ft (3 m); intermediate, 0–33 ft (3–10 m); or large, more than 33 ft (10 m) The majority of species (47) are small, 31 species are intermediate, and only 11 species are large (see here)
Anatomy of a mysticete and odontocete
The whale’s skeleton shows numerous adaptations for life in the water. The forelimbs are reduced and flattened into paddles. The elbow joint is immobile and since it is enclosed in the flipper the forelimb is used mostly for steering. The finger bones are lengthened by additional bony elements that serve to increase the surface area of the flipper. The hind limbs are reduced to a few vestigial bones embedded in muscle. The vertebral column has large spines to anchor the powerful fluke muscles that provide propulsion. Some or all of the neck vertebrae (seen in the bowhead, right) are fused; this inhibits neck mobility, which is important in maintaining hydrodynamic efficiency. The dorsal fin (seen in the dolphin below) is similar to the fluke in its lack of bony support and connective tissue composition. Odontocete (bottlenose dolphin)
Mysticete (bowhead whale)
Generalized dolphin’s head
Sound production and reception
The dolphin’s soundproduction andhearing systems have undergone extensive modification to enable them toperceive andinterpretunderwater sound Sounds areproducedby the movementofair between thephonic lips The opening andclosing ofthephonic lips breaks up the air flow and producespulsedsounds or clicks The melon acts as an acoustic lens to focus sounds into the water The externalears have disappearedandnewpathways ofsoundreception to the inner ear have evolved, including the fat-filledchannels ofthe lowerjaw.
The muscular horizontal tail or fluke lacks bony support and is composed of tough, fibrous connective tissue. The tail provides propulsion by vertical movement. Tail shape differs among cetaceans and most provide increased efficiency at high speeds (see Identification). To help minimize drag in the water many smaller odontocetes, for example delphinids, move at high speed and leap and glide (porpoising) above the water’s surface. Most whales have a dorsal fin (see also Identification) that provides stability and balance.
The fins, flippers, and flukes of cetaceans have arteries and veins that pass close to one another in opposite directions and function as radiators (counter current exchangers) to control heat balance. The skin of cetaceans is generally smooth and rubbery to the touch. Hair is absent except for sparse bristles (vibrissae) found on the head of some species. The blubber layer, thickest in large baleen whales, enhances streamlining and provides insulation and energy storage.
Mysticetes don’t have teeth as adults and have evolved novel feeding structures baleen plates composed of keratin (the material that makes up the hair, claws, and fingernails of mammals) that hang down from the upper jaw and strain bulk prey, for example, krill. Rorquals, such as fin whales, can engulf a volume of water that is greater than their body mass. For example, fin whales have been reported to engulf 18,000 gallons (70,000 liters) of water in each gulp, containing 22 lb (10 kg) of krill. Expansion of the mouth and throat in mysticetes is facilitated by external throat grooves or pleats below the mouth and throat Most odontocetes, especially those with diets of schooling fish, employ their many teeth to obtain prey. Odontocetes are active hunters and pursue prey using echolocation, in which high-frequency sounds are emitted from “phonic lips” near the blowhole. Sounds are focused by the melon, a fatty structure on the top of the head, and returning echoes pass through and under fat bodies on the lower jaw before being transmitted to the ears.
Beaked and sperm whales have fewer or no teeth and are deep divers, feeding primarily on squid. Cuvier’s beaked whales hold the diving record and are the longestand deepest-diving vertebrates, with dives lasting 137 minutes to depths of more than 1.86 miles (2,992 m) on a single breath. Deep-diving cetaceans exhibit a variety of circulatory and respiratory modifications including high blood volume, flexible ribs, and tolerance of complete lung collapse By contrast with human lungs, large oxygen stores are located in the muscles and blood.
A feature of some whale brains is their large size, especially the cerebrum, the front portion of the brain responsible for movement and mental functions. Brain size relative to body size is large in odontocetes. In comparison to other similar-sized animals most odontocetes have brains that are four to five times larger. Only the human brain is proportionally larger. The high brain:body size ratio of odontocetes, such as dolphins and killer whales, are partly explained by their complex social structure and behavior.
