A CLASSIFICATION OF LIVING CETACEANS Marine Mammal Biology SIO 133 Spring 2012 Lisa T. Ballance MARINE MAMMALS -- Mammals which obtain all or most of their food from the sea ORDER CETACEA completely independent of land skin essentially lacking hair, although present in newborns and as vibrissae in Mysticetes well-developed layer of blubber pectoral limbs modified as flippers hyperphalangy --increased number of bones in digits hind limbs absent pelvic girdle reduced to two free-floating bones --inominates tail modified into flukes no external pinna nostrils modified as a blowhole skull greatly modified --telescoping SUBORDER MYSTICETI "Mustached Ones" no functional teeth, although approximately 50 present in fetus baleen plates to strain prey 2 external blowholes skull symmetrical vibrissae present large body size (7 33+ m in length) including the largest animals ever to live females larger than males most make long-range, seasonal migrations, summering in high latitudes and wintering in low latitudes group sizes tend to be small (1-3) FAMILY BALAENIDAE - right whales (2 genera, 4 species) no dorsal fin 5 digits 7 cervical vertebrae fused extremely convex profile of upper surface of skull
head ~1/3 of body length all oceans except northern Indian Ocean neritic when calving; generally oceanic when feeding Ecology longest, finest baleen of all mysticetes generally slow swimmers, low maneuverability Eubalaena glacialis Eubalaena japonica (described within past 15 years) Eubalaena australis Balaena mysticetus FAMILY NEOBALAENIDAE - pygmy right whale (1 genus, 1 species) short, falcate dorsal fin one pair of shallow gular grooves moderately arched mouthline head ~1/4 of body length temperate-to-sub-polar oceans of Southern Hemisphere Ecology poorly known Caperea marginata FAMILY BALAENOPTERIDAE - rorquals (2 genera, 8 species) large body size (all > 7 m in body length; include largest animals to live on earth) dorsal fin small, set behind midpoint of back numerous, lengthy gular grooves 4 digits present --third digit absent 7 cervical vertebrae --not fused upper surface of skull with flat profile all oceans of the world; all latitudes; oceanic and neritic waters Ecology baleen generally intermediate in length and thickness; minke whale with shortest baleen (~20 cm in length) generally fast swimmers, highly maneuverable Balaenoptera musculus Balaenoptera physalus Balaenoptera borealis Balaenoptera brydei (soon to be described) Balaenoptera edeni Balaenoptera omurai (described within past 10 years) 2
Balaenoptera acutorostrata Balaenoptera bonaerensis (described within past 15 years) Megaptera novaeangliae FAMILY ESCHRICHTIIDAE - gray whale (1 genus, 1 species) dorsal hump (no dorsal fin) 2-5 gular grooves 4 digits present --first digit absent 7 cervical vertebrae --not fused upper surface of skull with slightly convex profile restricted to coastal waters of the eastern Pacific relict population present in the western Pacific North Atlantic population extirpated within last 300 hundred years Ecology short, stiff baleen (~40 cm in length) body usually covered with barnacles and whale lice slow-moving largely benthic feeders in shallow waters Eschrichtius robustus Western Pacific population critically endangered SUBORDER ODONTOCETI "Toothed Ones" homodont teeth present (can be buried in gum/jawbone) 1 external blowhole skull asymmetrical complex system of nasal sacs fatty melon in head capable of echolocation small-to-medium body size (male sperm whales excepted) most species sexually dimorphic FAMILY PHYSETERIDAE sperm whale (1 genus, 1 species) dorsal hump (no dorsal fin) conical teeth confined to lower jaw; fit into sockets in upper jaw head extends beyond lower jaw extreme cranial asymmetry blowhole at left, anterior section of head largest odontocete highest degree of sexual dimorphism of all cetaceans (males larger than females) 3
all oceans of the world; all latitudes; mainly oceanic males occur in polar regions; females and immatures largely restricted to tropical and temperate regions capable of dives to extreme depth (2000+ m) and length (> 2 h) mainly squid eaters genetically-related groups (matrilines) believed to remain together for life Physeter macrocephalus FAMILY KOGIIDAE pygmy and dwarf sperm whales (1 genus, 2 species) dorsal fin present extreme cranial asymmetry unique pigmentation mark on lateral sides of head/neck blunt head underslung jaw oceanic waters in tropical to temperate regions, all oceans of the world capable of deep dives mainly squid eaters small group sizes (typically < 5) poorly known Kogia breviceps Kogia sima FAMILY MONODONTIDAE narwhal and beluga (2 genera, 2 species) cervical vertebrae generally not fused no dorsal fin teeth o narwhal --2 in upper jaw of males only left canine spirals left to become tusk o beluga --8-10 in upper jaw head blunt --no distinct beak body size < 6 m restricted to polar seas in Northern Hemisphere group sizes generally < 10 but can number in the 1000s diet diverse Monodon monoceros 4
Delphinapterus leucas FAMILY ZIPHIIDAE - beaked whales (6 genera, 21+ species) small dorsal fin set far back on body 2 gular grooves teeth: 1-2 pairs, confined to lower jaw of males (exceptions: Berardius males and females w/ 2 pairs of exposed teeth; Tasmacetus both sexes with long rows of functional teeth in upper and lower jaws) flukes without notch small flippers; fit into grooves on sides of body jaws extend beyond head into a distinct beak medium body size (4-13 m in length) females usually larger than males oceanic waters of all oceans, all latitudes capable of dives extreme in depth and length mainly squid eaters Mesoplodon with small group sizes (<5); other genera with larger group sizes poorly known Berardius bairdii Berardius arnuxii Ziphius cavirostris Hyperoodon ampullatus Hyperoodon planifrons Tasmacetus shepherdi (first identified in the wild in 2000s) Mesoplodon densirostris Mesoplodon grayi Mesoplodon ginkgodens (known only from stranded specimens) Mesoplodon hectori Mesoplodon perrini (described within past 10 years; known only from stranded specimens) Mesoplodon carlhubbsi Mesoplodon peruvianus (described within past 20 years) Mesoplodon bidens Mesoplodon europaeus Mesoplodon mirus Mesoplodon layardii Mesoplodon bowdoini (known only from stranded specimens) Mesoplodon stejnegeri Mesoplodon traversii ((described within past 15 years; known only from skeletal material) Indopacetus pacficus (first identified in the wild in 1990s) Mesoplodon hotaula??? (possible new species) FAMILY DELPHINIDAE - dolphins (17 genera, 36 species) 5
dorsal fin of various sizes and shapes, with exception of Lissodelphis (no dorsal fin) teeth well-developed, conical, present in both jaws jaws extend beyond head into a distinct beak (exceptions exist) body size small to medium (~2 10 m in length) all oceans of the world; neritic and oceanic; all latitudes highly diverse w/r/t diet often occurs in large schools Orcaella brevirostris Orcaella heinsohni (described within past 10 years) Orcinus orca Globicephala melas Globicephala macrorhynchus Pseudorca crassidens Feresa attenuata Peponocephala electra Sotalia fluviatilis Sotalia guianensis (described within past 15 years) Sousa chinensis Sousa teuszii Steno bredanensis Lagenorhynchus obliquidens Lagenorhynchus obscurus Lagenorhynchus albirostris Lagenorhynchus acutus Lagenorhynchus cruciger Lagenorhynchus australis Grampus griseus Tursiops truncatus Tursiops aduncus Stenella attenuata Stenella frontalis Stenella longirostris Stenella clymene (described within past 20 years) Stenella coeruleoalba Delphinus delphis Delphinus capensis (described within past 25 years) Lagenodelphis hosei (first identified in the wild in 1970s) Lissodelphis borealis Lissodelphis peronii Cephalorhynchus commersonii Cephalorhynchus heavisidii Cephalorhynchus hectori 6
Cephalorhynchus eutropia Tursiops australis??? (possible new species described) Orcinus, Sousa??? (possible new species to be described) FAMILY PHOCOENIDAE - porpoises (3 genera, 7 species) dorsal fin large and triangular, with exception of Neophocaena (no dorsal fin) teeth well to poorly developed, spatulate, present in both jaws head blunt with no distinct beak small body size (all < 2.5 m in length) females larger than males in some species (but males larger in P. dioptrica and Ph. dalli) all oceans of the world; often neritic with restricted ranges but some oceanic species; one riverine form; all latitudes except polar highly diverse w/r/t diet group sizes typically small (< 5) Phocoenoides dalli Phocoena phocoena Phocoena dioptrica Phocoena spinipinnis Phocoena sinus Neophocaena phocaenoides Neophocaena asiaeorientalis RIVER DOLPHINS 4 families dorsal fin usually low and sub-triangular teeth well developed, conical, present in both jaws extremely long beak poor vision in riverine forms heavy reliance on echolocation features common due to convergence feed mainly on fish small group sizes poorly known FAMILY PLATANISTIDAE South Asian river dolphin (1 genus, 1 species) distribution restricted to large river systems of South Asia (mainly Ganges and Indus) 7
Platanista gangetica FAMILY INIIDAE boto (1 genus, 1 species) distribution restricted to Amazon and Orinoco rivers and drainages, South America distinct pink coloration Inia geoffrensis??? (possible new species described) FAMILY LIPOTIDAE baiji (1 genus, 1 species) distribution restricted to Yangtze River declared extinct in 2007 (Turvey et al. 2007. Biology Letters) Lipotes vexillifer FAMILY PONTOPORIIDAE franciscana (1 genus, 1 species) distribution restricted to coastal waters of southeast South America Pontoporia blainvillei 8