Whales, Dolphins, and Porpoises of the 

 Western North Atlantic 



A Guide to Their Identification 



STEPHEN LEATHERWOOD,' DAVID K. CALDWELL/ and 

 HOWARD E.WINN' 



with special assistance by 

 WUliam E . Schevill * and Melba C . Caldwell ' 



ABSTRACT 



This field guide is designed to permit observers to identify the cetaceans (whales, dolphins, and porpoises) 

 they see in the western North Atlantic, including the Caribbean Sea. the Gulf of Mexico, and the coastal 

 waters of the United States and Canada. The animals described are grouped not by scientific relationships but 

 by similarities in appearance in the field. Photographs of the animals in their natural environment are the main 

 aids to identification. 



A dichotomized key is provided to aid in identification of stranded cetaceans and appendices describe how 

 and to whom to report data on live and dead cetaceans. 



INTRODUCTION 



All whales, dolphins, and porpoises belong to an order or 

 major scientific group called the Cetacea by scientists. They 

 are all mammals (air-breathing animals which have hair in at 

 least some stage of their development, maintain a constant 

 body temperature, bear their young alive, and nurse them for 

 a while) which have undergone extensive changes in body 

 form (anatomy) and function (physiology) to cope with a life 

 spent entirely in the water. The breathing aperture(s), called 

 a blowhole or blowholes, has (have) migrated to the top of the 

 head to facilitate breathing while swimming; the forward 

 appendages have become flippers; the hind appendages have 

 nearly disappeared, they remain only as small traces of bone 

 deeply imbedded in the muscles. Propulsion is provided by 

 fibrous, horizontally flattened tail flukes. 



Scientists recognize two suborders of living cetaceans: the 

 whalebone whales, suborder Mysticeti, and the toothed 

 whales, suborder Odontoceti. The two groups are separated 

 in the following ways: 



BALEEN OR WHALEBONE WHALES. These animals are 

 called whalebone whales because when fully formed instead 

 of teeth they have up to 800 or more plates of baleen or 

 whalebone depending from the roof of the mouth. They use 

 these plates to strain their food, which consists of "krill" 



'Biomedical Division, Undersea Sciences Department, Naval 

 Undersea Center, San Diego. CA 92132. 



'Biocommunication and Marine Mammal Research Facility, 

 C. V. Whitney Marine Research Laboratory of the University of Florida, 

 St. Augustine, FL 32084. 



'Graduate School of Oceanography, University of Rhode Island. 

 Kingston, RI 02881. 



'Woods Hole Oceanographic Institution. Woods Hole, MA 02543 and 

 Museum of Comparative Zoology, Harvard University, Cambridge, MA 

 02138. 



(primarily small crustaceans) and/or small schooling fish, by 

 taking water into the mouth and forcing it out through the 

 overlapping fringes of the baleen plates. Baleen whales are 

 externally distinguishable from toothed whales by having 

 paired blowholes. There are eight species of baleen whales in 

 the western North Atlantic, ranging in size from the minke 

 whale (just over 30 feet [about 9.1 m])'to the blue whale (85 

 feet [25.9 m]). 



TOOTHED WHALES. Unlike the baleen whales, the toothed 

 whales do have teeth after birth. The teeth vary in number 

 from 2 to over 250, though they may sometimes be concealed 

 beneath the gum. In addition, toothed whales have only a 

 single blowhole. This group includes the animals commonly 

 called dolphin or porpoise as well as some commonly called 

 whales (for example, the sperm whale). There are currently 

 about 30 species of toothed whales known from the western 

 North Atlantic, ranging in maximum adult size from the 

 common or harbor porpoise, which is approximately 5 feet 

 (1.5 m) long, up to the sperm whale which reaches a length of 

 68 feet (20.7 m). Several other species which are expected to 

 be found in this region, though they have not yet been 

 reported, are also included in this guide. 



CLASSIFICATION OF CETACEANS 



In addition to the two suborders (Mysticeti and 

 Odontoceti), the cetacean order contains numerous families, 

 genera, and species. Each of these groupings represents a 

 progressively more specialized division of the animals into 

 categories on the basis of similarities in their skulls. 



'Throughout this guide, measurements are given first in feet or 

 inches, followed in parentheses by their equivalents in meters or 

 centimeters. It is recognized that field estimates cannot be as precise as 

 most of the conversions used. 



