1. I. I.Marine Mammals B. B.Pinnipedia (suborder) Many nest in rookeries Males establish territories and harems (polygynous) Females may have seasonal delayed implantation Fertilization and early development to blastocyst followed by delayed implantation Lactation period varies from days to months

2. Northern Fur Seals video

3. I. I.Marine Mammals B. B.Pinnipedia 1. 1.Sea Lions (6 species) Extremely common in E Pacific Highly social; usually congregate on shore Males can be large (up to 3+ m, 1100+ kg) Harems of up to 12 females 2. 2.Fur Seals (10 species) Related to sea lions Thick, dense fur Steller’s Sea Lion Antarctic Fur Seal California Sea Lion

4. I. I.Marine Mammals B. B.Pinnipedia 3. 3.True Seals (19 species) Highest diversity in polar regions (esp. Antarctic) Better adapted for aquatic existence vs. eared seals Include largest pinniped Southern elephant seals (males) can reach 6.5+ m (22 feet) long and 4000+ kg Tend not to have harems (pair for breeding season) Weddell LeopardCrabeater Harbor S. Elephant video

5. I. I.Marine Mammals B. B.Pinnipedia 4. 4.Walrus (1 species) No external ears; distinct neck; hind limbs for walking Feed on fishes and benthic invertebrates, esp. clams Tusks used for defense or as anchors in ice Males can reach 5+ m, 1500+ kg Males defend harems (up to three females + calves) video

6. I. I.Marine Mammals C. C.Sirenia (4 species) Manatees (marine and freshwater), dugongs (exclusively marine), sea cows (extinct) Restricted to tropics (modern) Manatees reach 3.5 m, 550 kg Dugongs reach 4 m, 1000 kg Front flippers, vestigial pelvis, no hind limbs (similar to cetaceans), tail flukes Swim mainly with tail videovideo Thick blubber layer Strictly vegetarian videovideo Eat seagrasses and other vegetation

7. West Indian Manatee West African Manatee Amazonian Manatee Dugong

9. I. I.Marine Mammals D. D.Cetacea Whales, dolphins, porpoises ~90 species: ~85 marine Front flippers, tail, no rear limbs Many have dorsal fin (stability, along with flippers) Muscular tail ends in horizontal flukes Streamlined for efficient swimming Reduced/fused cervical vertebrae, no external ears/nostrils Limited hair Example of convergent evolution Blubber layer – Varies by species and season Insulation, energy, buoyancy Breathe through blowhole on dorsal surface Single – toothed whales Double – baleen whales Evolved from terrestrial ancestors

10. Fig. 12-10

11. I. I.Marine Mammals D. D.Cetacea Thermoregulation Eliminate heat: Shunt blood into blubber layer Retain heat: Countercurrent exchangers

12. Fig. 12-11

13. I. I.Marine Mammals D. D.Cetacea Diving adaptations Mammalian diving reflex Bradycardia (as low as 10 beats per minute) Peripheral vasoconstriction Most oxygen in tissues Nitrogen forced out of alveoli: prevents bends Collapsible ribcage Up to 2x more blood per unit body weight vs. humans 10-30x more myoglobin in muscles vs. land mammals Muscles less sensitive to lactic acid Medulla oblongata (controls breathing) less sensitive to CO 2

14. Fig. 12-12