Whales, Dolphins, and Porpoises of the Western North Atlantic Part 2

ORGANIZATION OF THE GUIDE

The differences between baleen and toothed whales are easy enough to see in animals washed up on the beach or maintained in a tank at a zoo or aquarium. But since an animal at sea can seldom be examined that closely, its most obvious characteristics may be its overall size, the presence or absence of a dorsal fin, its prominent coloration or markings, its general behavior, or its swimming, blowing, and diving characteristics. For that reason, regardless of their scientific relations.h.i.+ps, all the whales, dolphins, and the one porpoise covered in the main text of this guide are divided into three groups. Those over 40 feet (12.2 m) long are discussed in the section on Large Whales, those from 13 to 40 feet (4.0 to 12.2 m) in the Medium-Sized Whale, and those less than 13 feet (4.0 m) in the Small Whales, Dolphins, and Porpoise (with a dorsal fin). There are no small whales, dolphins, or porpoises in this region without a dorsal fin. Each section is further divided into those animals with a dorsal fin and those without. From that point, animals likely to be confused in the field are grouped together and the important differences between them are discussed.

The synoptic accounts of the species are followed by five appendices: Appendix A discusses and ill.u.s.trates man-made and applied tags and natural markings on cetaceans and their importance in studies of natural history. Appendix B discusses the data which are most important to record in observations of cetaceans at sea, gives examples, and provides blank sighting forms. Appendix C discusses possible causes of cetacean strandings and the manner in which stranded animals should be handled and adds a key and tables to aid in identifying stranded cetaceans.

Appendix D provides guidelines for collecting data on stranded cetaceans and provides forms and specific instructions for taking standard measurements. Appendix E lists inst.i.tutions to be contacted in the event of a cetacean stranding or for information.

A bibliography of useful references on cetaceans in general and cetaceans of this region in particular and a directory to species accounts are included.

[Ill.u.s.tration: Figure 5.--A humpback whale lying on its left side on the deck of a Canadian whaling station. Note the fringes of baleen suspended from the roof of the mouth. (_Photo by J. G. Mead_.)]

[Ill.u.s.tration: Figure 6.--Atlantic bottlenosed dolphin mother and calf from northeastern Florida. Note the single open blowhole, a characteristic that marks these animals as toothed whales. (_Photo courtesy of Marineland of Florida._)]

[Ill.u.s.tration: Figure 7.--The open mouth of an Atlantic bottlenosed dolphin from the northeastern Gulf of Mexico. All toothed whales have teeth, which are used primarily for grasping rather than for chewing.

The number varies from 2 to over 250, though they are buried beneath the gums in females and immature animals of several species, take peculiar form in one (narwhal), and are extensively worn in others. (_Photo by D.

K. Caldwell._)]

HOW TO USE THE GUIDE

To Identify Animals at Sea

The three major sections of the guide (i.e., large, medium, and small whales) are preceded by a directory to species accounts, which is a summary of the most obvious characteristics of each species and in which summary statements about each characteristic are arranged in parallel order. To use the guide to identify living animals observed at sea, a person or persons should:

1. First estimate the animal's size and determine whether or not it has a dorsal fin.

2. Note also any distinctive features of body shape and coloration and observe its general behavior, including swimming, blowing, and diving characteristics. It should be noted that coloration may vary somewhat at sea, depending on light conditions and water clarity. For example, animals which appear dark gray or black at the surface or when dead may appear brown in good light or when submerged. Making a brief sketch at this point may aid in identifying the animal or in later recalling its distinctive features.

3. Using the directory, locate the section to which the animal probably belongs.

4. Then, for more detailed information, consult the section indicated.

There you will find a more complete discussion of the animal's range, size, and distinctive characteristics. In addition, you will find a brief discussion distinguis.h.i.+ng it from animals with which it is likely to be confused in the field.

This guide will probably work best if, in advance of attempting to use the key in the field, the reader will familiarize himself with the general outline, with characters or behaviors to note, and with the locations of the various species accounts. It will also help if he schools himself to ask a series of questions about the animal(s) he sees at the time of the encounter rather than depending on his recall at a later time (see p. 160). As we have emphasized several times in this guide, positive identification of cetaceans at sea can only occasionally be made on the basis of a single characteristic. Therefore, the greater the amount of pertinent evidence an observer obtains, the greater the likelihood he can make a reliable identification.

To Identify Stranded Animals

Stranded animals can best be identified by referring to Appendix C and its a.s.sociated tables, making a preliminary determination and then consulting the species accounts in the main body of the book for verification of the identification. As noted in that appendix, if the animal is recently stranded, identification can be made using any of the externally visible characteristics described for the living species at sea. But even if the animal is in an advanced stage of decomposition, it can usually be identified by referring to the key and to the numbers and descriptions of baleen plates, for all baleen whales, and the numbers and relative lengths of ventral grooves, for all balaenopterine whales (Table 1), or to the tables on the numbers and descriptions of teeth, for toothed whales (Table 2).

To Record and Report Information

As discussed in the preface, though learning to identify the whales, dolphins, and porpoises one sees may be exciting in itself, many persons may want to partic.i.p.ate in the acc.u.mulation of data on these interesting animals by routinely reporting their observations to scientists who are actively studying them and who can make immediate use of the information. The following may help these persons:

Suggestions for making and recording observations of cetaceans at sea and sample data forms are included in Appendix C. Similar suggestions for taking and recording data on stranded cetaceans are included in Appendix D. For both types of data, blank data forms located after the appendices may be photocopied in bulk for use in the field.

Completed data forms and all a.s.sociated information for sightings at sea should be forwarded to the Platforms of Opportunity Program, National Marine Fisheries Service, Tiburon, CA 94920, or to one of the authors of this guide. From there, they will be made available to scientists actively studying the cetaceans of a given species or geographical area.

Completed data forms and all a.s.sociated information for observations of stranded cetaceans should be forwarded to the Division of Mammals, U.S.

National Museum, Was.h.i.+ngton, DC 20560, to one of the authors of this guide, or to one of the regional laboratories listed in Appendix E.

These persons have, in turn, been encouraged to keep a free flow of information among them.

Table 1. Ranges in Numbers of Teeth in Each Upper and Lower Jaw of Western North Atlantic Odontocetes.

[P] = Page of species account ------------------------------------------------------------------------------ Ranges in tooth counts Species -----+----- Species common name scientific name [P] Upper Lower Remarks --------------------+----------------+---+-----+-----+------------------------ Sperm whale _Physeter_ 57 0 18-25 Ten to sixteen upper _catodon_ teeth _rarely_ emerge; lower teeth fit into sockets in upper jaw.

Northern _Hyperoodon_ 67 0 2(2) At tip of lower jaw; bottlenosed whale _ampullatus_ [A] sometimes second pair behind first.

Goosebeaked whale _Ziphius_ 70 0 2[A] At tip of lower jaw.[B]

_cavirostris_ True's beaked whale _Mesoplodon_ 77 0 2[A] At tip of lower jaw.[B]

_mirus_ Antillean beaked _Mesoplodon_ 78 0 2[A] At suture of mandible.

whale _europaeus_ One-third of way from tip of snout to gape.[B]

Dense-beaked whale _Mesoplodon_ 80 0 2[A] On prominences near _densirostris_ corner of mouth; oriented backwards.[b]

North Sea beaked _Mesoplodon_ 82 0 2[A] About halfway from whale _bidens_ tip of snout to gape.[B]

Killer whale _Orcinus orca_ 84 10-12 10-12 Prominent; curved and oriented backwards and inwards; pointed.

False killer whale _Pseudorca_ 88 8-11 8-11 Prominent; pointed _cra.s.sidens_ and curved.

Atlantic pilot whale _Globicephala_ 91 8-10 8-10 -- -- _melaena_ Short-finned pilot _Globicephala_ 94 7-9 7-9 -- -- whale _macrorhyncha_ Grampus _Grampus_ 96 0 0-7 Near front of jaw; _griseus_ may have fallen out in older specimens; sometimes teeth in upper jaw.

Beluga _Delphinapterus_ 99 8-11 8-9 -- -- _leucas_ Narwhal _Monodon_ 102 2 0[A] One (rarely both) _monoceros_ grows up to 9 ft (2.5 m) tusk which has left-hand (sinestral) spiral.

Spotted dolphin _Stenella_ 104 30-36 28-35 -- -- _plagiodon_ Bridled dolphin _Stenella_ 108 29-34 33-36 -- -- _frontalis_ Spinner dolphin _Stenella_ 110 46-65 46-65 -- -- _longirostris_ Striped dolphin _Stenella_ 113 43-50 43-50 -- -- _coeruleoalba_ Saddleback dolphin _Delphinus_ 116 40-50 40-50 -- -- _delphis_ Fraser's dolphin _Lagenodelphis_ 120 38-44 38-44 -- -- _hosei_ Atlantic white-sided _Lagenorhynchus_ 123 30-40 30-40 Some specimens have dolphin _acutus_ more teeth in upper than in lower jaw.

White-beaked dolphin _Lagenorhynchus_ 126 22-28 22-28 -- -- _albirostris_ Atlantic bottlenosed _Tursiops_ 128 20-26 18-24 -- -- dolphin _truncatus_ Guiana dolphin _Sotalia_ 132 26-35 26-35 -- -- _guianensis_ Rough-toothed _Steno_ 135 20-27 20-27 Crown is sometimes dolphin _bredanensis_ marked with many fine vertical wrinkles.

Pygmy killer whale _Feresa_ 138 8-13 10-13 Many specimens have.

_attenuata_ fewer teeth on right than on left side.

Many-toothed _Peponocephala_ 142 22-25 21-24 -- -- blackfish _electra_ Pygmy sperm whale _Kogia_ 144 0 12-16 Rarely 10 or 11; _breviceps_ curved back and inwards; fit into sockets in upper jaw.

Dwarf sperm whale _Kogia simus_ 148 0-3 8-11 Rarely 13; curved back and in; sharply pointed; fit into sockets in upper jaw.

Rarely has 1-3 upper teeth as well.

Harbor porpoise _Phocoena_ 150 22-28 22-28 Spade shaped, laterally _phocoena_ compressed, and relatively small.

[Footnote A: Usually erupted from gums only in adult [MALES].]

[Footnote B: May have toothpick size vestigial teeth in either jaw.]

Table 2. Body Size; Numbers, Maximum Dimensions and Descriptions of Baleen Plates; and Numbers and Relative Lengths of Ventral Grooves of W.

N. Atlantic Mysticetes.

----------------------------------------------------------------------------- Maximum dimensions of plates ------------------- Number Width Maximum of Length base Page of body baleen ----+----+----+---- Species Species species size[C] plates/ ft/ ft/ common name scientific name account ft(m) side in. cm in. cm -------------+---------------+-------+---------+--------+----+----+----+---- Blue whale Balaenoptera 19 85 (26.0) 270-395 33" 84 12" 30 musculus Fin whale Balaenoptera 26 79 (24.0) 262-473 29" 72 12" 30 physalus Sei whale Balaenoptera 32 62 (19.0) 318-340 31" 78 15" 39 borealis Bryde's whale Balaenoptera 37 46 (14.0) 250-300? 17" 42 10" 24 edeni Humpback Megaptera 40 53 (16.0) 270-400 24" 60 5" 13 whale novaeangliae Bowhead whale Balaena 49 65 (19.8) 325-360 14' 414 14" 36 mysticetus Right whale Eubalaena 52 53 (16.0) 250-390 7.3' 223 12" 30 glacialis Minke whale Balaenoptera 63 31 (10.0) 300-325 8" 21 4" 10 acutorostrata -----------------------------------------------------------------------------

----------------------------------------------------------------------------- Mean No. Numbers of of Species bristles ventral Relative lengths common name Color of baleen /cm. grooves of ventral grooves --------------+------------------------+--------+---------+------------------ Blue whale All black with black 10-30 55-88 At least to navel.

bristles. Fin whale Dark gray to bluish 10-35 56-100 At least to navel.

gray; one-fifth to one-third of right front is whitish. Sei whale Ash black with blue 35-60 38-56 End far short of tinge and fine, light navel.

bristles; some near front may be light. Bryde's whale Slate gray with dark 15-35 40-50 At least to navel.

bristles. Humpback whale Ash black to olive 10-35 14-22 At least to navel.

brown; sometimes whitish; bristles grayish white. Bowhead whale Black; anterior ? None XX side of some is present. whitish; bristles black. Right whale Dirty or yellowish gray; 35-70 None XX some anterior plates present. all or part white. Minke whale White to yellowish 15-25 50-70 End short of white. Posterior plates navel; often just may be brown or black. behind flippers.

[Footnote C: As stated in the Index to the species, these figures represent maximum sizes recorded for the W. N. Atlantic. For all species exploited by whaling industries' current maximum sizes will be substantially smaller than these figures (see species accounts).]