Marine Mammals

1. Marine Mammals By Sara Harsley

2. Introduction to marine orders • Cetacea- • includes whales and dolphins • Pinnipedia • Phocidae-true and fur seals • Otaridea-eared seals • Odobenidae-walrus • Carnivora • Ursidae-polar bears • Mustelidae-otters • Sirenia • Includes manatees and dugongs

3. Pinnipedia • Examples: true seals, eared seals, and the walrus • The closest living relatives of seals Carnivora, such as bears and weasels • Believed to have separated from Carnivora between 15 and 25 million years ago • Inhabit coastal waters off continents or islands. • Typically inhabit the colder waters of the north and southern hemisphere www.britannica.com

4. Characteristics of Pinnipeds • Streamlined, spindle shaped body • Rounded head • All 4 limbs modified into flippers • Internal reproductive organs • Ear pinna reduced or absent www.marinemammals.org

5. Characteristics of Pinnipeds • Spend majority of time in water to feed or migrate • Return to land to rest or breed • Large amounts of blubber

6. Phocidae includes the true seals Ex. Elephant seals, leopard seals Characteristics: Lacks ear pinna Propels itself through water with hindflippers Moves on land by shifting weight alternately on chest and pelvis – “inchworming” The Family Phocidae www.mmc.org

7. Otaridae comprises the eared seals Ex:Sea lions, fur seals Characteristics Reduced ear pinna Propels itself through water with foreflippers When moving on land, the body is kept off the ground by the powerful foreflippers and the heel of the hindflippers and gallops along The Family Otaridae www.nightskypictures.com

8. Odobenidae includes the walrus Ex.: the Atlantic and Pacific walrus Extremely large, weighing between 2000-3000 lbs. Thick, knobby skin Propels itself in the water with hindflippers Slow swimmer The family Odobenidae

9. Pinnipeds often consume fish or crustaceans (crabs, krill) Teeth can be modified into elaborate cusps to process the hard shells of crustaceans Or their teeth can be simple or peg-like to catch and consume fish Diet

10. Swimming and diving • Pinnipeds actively search for prey in dark and cold waters • Acute hearing, and light-sensitive vision enable them to search and pursue prey • Their sense of touch is also excellent, with long sensitive vibrissae located on the snout to help locate prey • Echolocation may also play apart in pinniped adaptations, but little

11. Swimming and Diving • Speed of swimming can be rapid due to streamlined body by reducing drag and with powerful flippers • Blubber beneath skin also helps reduce drag

12. Swimming and Diving • Deep diving poses risk to the animal • Nitrogen bubbles can form in the tissues • Pressure increases with depth • Lack of oxygen • Pinnipeds have evolved adaptations to deal with these problems during diving

13. Capable of absorbing more oxygen per breath due to increased erythrocytes in the blood and more myoglobin in muscle Exhale most of the air in their lungs before diving to reduce the amount of nitrogen in their systems Large amounts of blubber and fat help absorb gas bubbles from the blood stream Nares are adapted to collapse due to water pressure and reduce the likelihood of water rushing into lungs The tongue and a flap of skin from the soft palate form a buccal flap to prevent water from rushing into their system Adaptations to diving

14. Adaptations to heat and cold • Waters pinnipeds dive in average at –1.8 degrees C • Risk of hypothermia • Adaptations to the cold: • Blubber between 3-4 in thick • Pinnipeds are fairly large with reduced surface area • Regional heterothermy of the extremities reduce heat loss • Bradycardia • Blood can be shunted to vital organs • High metabolism • Some pinnipeds have thick fur coats

15. Adaptations to heat and cold • Pinnipeds are well adapted to cold environments and reducing body temperature can be difficult • Regional heterothermy and fanning flippers • Avoiding warm beaches on sunny days • Diverting blood to surface of skin called blushing • Molting

16. Reproduction • Breed once a year • Females aggregate in massive colonies ranging from a few hundred to a few thousand • Dominant males known as beach masters will form harems of several females • Gestation lasts about 12 months • Females mate a few days or weeks after giving birth • Delayed implantation of the embryo lasts 4 months • Females lactate for several months

17. Predation • Whales • Sharks • Other larger seals • Humans

18. Man and Pinnipeds • Stone age man relied on pinnipeds as a source of meat, ivory, furs, and skins • An industry developed of hunting seals and walrus • Prior to the 18th century, the hunting of seals and walrus did not deplete populations

19. Man and Pinnipeds • With the advent of guns and harpoons, hunters were able to take massive numbers of seals and walrus • Many species such as the Antarctic fur seal soon faced extinction

20. Man and Pinnipeds • Legislation was passed to ban or limit seal hunting: • Ex. 1911 Pacific Fur Seal Convention • Although greatly limited, seal hunting continues in some countries such as Canada • This issue still remains controversial

21. Man and Pinnipeds • Dangers to seals: • Many believe that pinnipeds compete with the fishing industry • Eat fish • Cod worm • Seals are commonly culled in an effort to reduce potential competition • Set nets and Trawlers • Pollution • Oil spills • Heavy metals • Organochlorine compounds

22. Man and Pinnipeds • Bans and restrictions on hunting have increased population • Tourism • Animal rights activists

23. Carnivora • Ursidae- • Polar bear • Mustelidae • Sea otter

24. Separated from the Grizzly bear line 70,000 years ago Northern arctic region Largest carnivorous quadruped The Polar Bear Ursus maritimus

25. The polar bear • Characterisitics: • Elongated head and neck • Shorter ears • Thick, white, water repellent coat • Thick layers of fat • Partially webbed feet

26. Polar bear diet • Known to eat fish, seals, and even whales • Use keen sense of smell and hearing to locate Ringed seal pups in dens under the ice • Males are known to kill and eat walrus, beluga, and narwhals • Prefer hunting in areas of open water, heavy ice, newly frozen ice

27. Social Interactions • Mostly Solitary • May congregate to feed at large kills sites • Known to hunt cooperatively • Cubs remain with the mother between 2-3 years

28. Reproduction • Females mate every 3 years • Gestation lasts between 195-265 days due to delayed implantation • 1-3 cubs or born in December, during hibernation • Cubs remain with mother for up to 3 years

29. Polar bears and Man • Historically hunted and culled • Today restrictions and bans on hunting have reduced this threat: • 1973 Agreement on Conservation of Polar Bears • Convention on International Trade in Endangered Species • US Marine Mammal Protection Act of 1972 • Current threats include global warming and habitat destruction

30. Sea Otter Enhydra lutris • Inhabits coastal and estuarine waters of the coast of California • Largest member of the Mustelidae • Spends majority of time in the water and rarely comes ashore

31. Sea otter diet • Feeds primarily on sea floor invertebrates like sea urchins, abalones, and mussels • Large, rounded molars • Tool usage • Smashes sea urchins with stone to get to meat

32. Social interactions • Most mustelids like the sea otter are intelligent and extremely social • Females with young tend to congregate together in resting areas • Males will separate into groups apart from females • Groups come together to play, groom, and seek protection from predators

33. Reproduction • The breeding season lasts between 4-5 months • Gestation last 9 months with delayed implantation • Females will give birth to 1 cub • Mothers invest much energy and care in their young

34. Sea otters and Man • The sea otter was once hunted for pelts • Faced extinction • Current bans on taking and hunting sea otters as well as reintroduction programs have increased the population • Threats include habitat destruction and pollution

35. Sirenia • Includes manatees and dugongs • Evolved between 54-38 million years ago during Eocene period • Closely related to ungulates and elephants • Limited to warm tropical waters

36. Characteristics of Sirenia • Streamlined body • Low metabolic rate • Long lifespan (33 yrs) • Blubber helps regulate body temperature

37. Dugonidae • This family includes Dugong dugong also known as the Dugong or sea cow • Closest relatives is the know extinct Stellar’s Sea Cow • Has concave tail fin • Angled skull • Truly marine as it inhabits open, shallow, warm waters

38. Trichechidae • Includes manatees, Trichechus spp. • Has rounded, horizontal paddle-shaped tail • Usually feed along coastline, estuaries, or large rivers • Threatened

39. Sirenia diet • Non-ruminant herbivore • Hindgut fermented with large cecum • Massive intestine • Feed on seagrass meadows, algae, and other rooted aquatics • Peg-like molars • Worn teeth lost from front and replaced with new back teeth • Chew vegetation with rough horny pads that cover upper and lower palate • Rakes vegetation into mouth with bristles and snout

40. Reproduction • Females give birth to a single calf • Gestation lasts about 1 months • Calves are weaned at about 12-18 months of age

41. Social interaction • Females spend much with offspring • Some manatees converge in large groups to feed or migrate • Most dugongs are not sociable • Have few predators

42. Man and Sirenia • Extensively hunted for meat and hide by sailors and hunters • Pollution • Injured by boats • Migrate upstream during winter

43. References • Kemp, M. J., 2004. Mammology: Adaptation, Diversity, and Ecology. McGraw-Hill Publishing, New York City, New York • Macdonald PhD., David, 1995. The encyclopedia of mammals. Andromeda Oxford Limited, New York City, New York