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Cetacea Cetacea Changes Over Evolutionary Time 10+ Families, 79 Species -- 30 Million Years 37 Mya Early to Middle Eocene, Ambulocetus About 50 Mya

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Cetacea Cetacea Changes Over Evolutionary Time 10+ Families, 79 Species -- 30 Million Years 37 Mya Early to Middle Eocene, Ambulocetus About 50 Mya Mammalogy 4764 Fall 2009 Cetacea Cetacea Changes over evolutionary time 10+ families, 79 species -- 30 million years 37 mya Early to middle Eocene, Ambulocetus about 50 mya. Pakistan. Basilosaurus 54 mya Listed Appendix I or II of CITES Savage and Long 1986 20 mya 40 mya Cetacea Coyote Changes in skull Common characters Cetacea “Migration” of bones Arrow is nostrils Vertebrae modifications Horse Fusiform body (cigar shaped) Nearly hairless Basilosaurus Blubber insulation No sebaceous glands Odontocete Mysticete Feldhamer Savage and Long 1986 Cetacea Cetacea Reproductive characteristics Common characters Gestation: 9.5 to 17 months More phalanges in Mammary glands in slits next to urogenital opening front digit than typical. Pilot Right Blue Human 1 Mammalogy 4764 Fall 2009 Cetacea Cetacea Odontocete Mysticete Differences in skull Mysticetes eating smallest prey because are filter feeders. Asymmetry Shape Note: length of skull 4 m! Teeth Echolocation Right whale moving along surface Feldhamer Compare to gray whale which stirs up / scoops / suctions from bottom sediments Cetacea Cetacea Gas exchange -- 2 layers of capillaries Locomotive adaptations Expiration of almost all air -- humans retain 20+% 2x as many erythrocytes per blood volume vs. terrestrial 2x to 9x concentration of myoglobin (stores oxygen) Force of muscles -- Heart rate declines to half on deep dives Humpback whale 30,000 kg out of water! Bypassing muscles Tolerance to high lactic acid levels 70 minute dives Insensitivity to CO2 levels Lungs collapse within 100 m of surface Swimming speed -- consistent with propelling out of water Many ribs not attached to sternum--allows collapse Lungs small relative to body size Flippers steer, Tail up/down for forward propulsion Volume of nonvascular air passages larger Trachea short and large diameter, internal support Dolphins: 36 km / hr Bronchioles shorter, braced by muscles and rings Killer whale: 55 km / hr Lungs have elastic fibers -- allows compression Pilot whale: 27 km / hr Blue whale: 37 km / hr for 10 minutes – 150,000 kg Cetacea: Suborder Mysticeti Cetacea: Balaenopteridae 4 families, 11 species in suborder Rorquals Right whales (Balaenidae) 2 genera, 6 recent species 2 genera, 3 recent species 11 m to 31 m long 18 m long, > 67,000 kg Head 1/3 of length Up to 160,000 kg in blue whale (Balaenoptera musculus) Feed on plankton/schooling fish Feed on copepods Examples: Bowhead whale Balaena mysticetus Humpback whale Megaptera movaeangliae Southern right whale Eubalaena australis Minke whale Balaenoptera acutorostrata Northern right whale Eubalaena glacialis Blue whale Balaenoptera musculus 2 Mammalogy 4764 Fall 2009 Cetacea: Eschrichtiidae Cetacea: Suborder Odontoceti Gray whale Eschrichtius robustus 6 families, 67 species 1 recent species Toothed whales 15 m long, 31,500 kg Echolocation is “trademark” 10,000 to 22,000 km migration May acoustically “stun” prey North Pacific in summer Vaughn 22-14 South to Korea or California Sperm whales: Sharks and squid in stomach with no marks. Bottom feeders Whales with injured jaws could obtain prey. Cetacea: Delphinidae Killer whale Orcinus orca Cetacea: Monodontidae 17 genera, 32 species 2 genera, 2 species 1.5 to 9.5 m long Narwhal Monodon monoceros 1 tooth (1/0) 50 to 7,000 kg Beluga Delphinapterus leucas Shallow dives, surface often Beluga 6 m, 2000 kg Gregarious Move up rivers in summer Cetacea: Physeteridae Cetacea: Ziphidae 2 genera, 3 species 6 genera, 19 species Sperm whale Physeter catodon Some species have yet Pigmy sperm whale (Kogia spp.) to be seen alive Physeter gregarious Stomach divided into Groups of 20-40 typical 4 to 14 Chambers. Dive for over an hour 3.
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