1. Marine Mammals
Picture: G. Bearzi

2. WHO ARE THEY?
Photo: web

3. Marine mammals Land-dwelling ancestors Warm-blooded Breathe air
Hair/fur
Bear live young
Mammary glands for milk
They all have 3 ear bones.

4. Three Categories of Marine Mammals
Cetacea (se-tay-she-ah)
whales, dolphins, and porpoises
Carnivora
polar bears, otters, seals, sea lions, walruses
Sirenia (sire-een-e-uh)
manatees and dugongs
Photo: web

5. CETACEA: Toothed whales
Photo: M. Bearzi ©2000

6. Bottlenose dolphin
Striped dolphin
Images: M. Demma
Common dolphin

7. Rough-toothed dolphin Globicephalo...
Risso’s dolphin
Killer whale
Focena comune
False killer whale
Images: M. Demma
Rough-toothed dolphin
Globicephalo...

8. Risso’s dolphin
Pilot whale
Images: M. Demma
Harbor porpoise

9. Cuvier’s beaked whale
Images: M. Demma
Sperm whale...

10. SPERM WHALE

11. Not much of a species barrier!

15. CETACEA:
Baleen whales
Photo: web

16. Fin whale
Right whale
Images: M. Demma
Sei whale
Humpback whale

19. Cetacea Adaptations for deep diving Use oxygen efficiently
Absorb 90% of oxygen inhaled (lots of capillaries)
Store large quantities of oxygen (lots of hemoglobin)
Reduce oxygen required for noncritical organs
Dive 10 min (dolphin) to 2 hours (Sperm Whale)
Muscles insensitive to buildup of carbon dioxide
Collapsible lungs

20. Temperature Regulation
Blubber (also for buoyancy and energy storage)
Counter-current blood flow –
warms blood as it returns to
core of body
Muscles generate heat
Low surface area to volume
ratio - little surface in contact
with water to lose heat

21. Oxygen blowhole (nostrils) on head – easier
Empty and fill lungs quickly (2 seconds for a fin whale)
Large lungs
High gas exchange rate (absorb 90% of oxygen - humans absorb 20%)

22. Oxygen Many red blood cells, hemoglobin – carries oxygen
myoglobin - carries additional oxygen
Shunt blood from non-vital organs (stomach, kidney) when diving to vital organs (brain, heart, muscles)
Slow heartbeat rate when diving

23. Propulsion Through the Water
Streamlined
Internalized body parts - ear, penis, mammary glands – reduces friction
Shorter appendages – forelimbs for steering
Loss of hind limbs
Loss of hair

25. Propulsion Through the Water
fluke (tail) for propulsion
Up and down (unlike fish = side to side)
↑ surface area
Also to identify individuals - like fingerprint
flippers – for steering and balance

26. Sensing the Environment
Good eyesight – but little to no light
echolocation - biological SONAR – find and maybe to stun prey
Very good hearing - sound travels faster in water than in air
ex: humpback songs for communication – social, territorial

27. Communication whistles Echolocation clicks
Cetaceans’ sensory world
SOUND
Communication whistles
Echolocation clicks
Photo: web

28. Cetaceans’ sensory world
Song of a whale
Photo: web
Dolphin whistles

29. Types of Whales Toothed whales – suborder Odontoceti
Baleen whales – suborder Mysticeti

30. Types of Whales – Toothed Whales
Have teeth – to catch prey, not chew
Eat mostly fish and squid - killer whales eat seals
Dive deeper
Most do not migrate
Ex: sperm, pilot, killer whales, dolphins, porpoises
Ex: sperm whales dive > 3,500 feet for giant squid, up to 75 minutes

31. Types of Whales – Baleen Whales
No teeth baleen plates to filter krill and other items
ex: blue whale eats 4 tons of krill per day
Not deep divers
ex: humpback - lung feeding (lunge forward, pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

32. Types of Whales – Baleen Whales
pleats – folds under mouth
open like accordion when feeding

33. baleen
ventral grooves
jaw
tongue
Image: from M. Jahoda book, modified

34. Feeding
Image: G. Bearzi
Other whales

35. Types of Whales – Baleen Whales
ex: humpback - lunge feeding (lunge forward, pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

36. Types of Whales – Baleen Whales
ex: blue, humpback, right, gray, fin
North to feed, south to breed - behavioral adaptation
north - summer for krill
south - winter to raise young
ex: gray whales, 3 month
migration, Arctic to Baja, CA,
6,000 mi one way

37. Order Carnivora Pinnipeds (large skin covered flippers) Walruses Seals
Sea lions
Fur seals

38. CARNIVORA: Pinnipeds Otariidae sea lions, fur seals, etc Phocidae
true seals
Photos: M. Bearzi ©2000

39. Family Phocidea (Pho-ce-die)
“True or Earless Seals”
No external ears
Flippers covered in fur
Hind flippers cannot be turned forward under the body for use in terrestrial motion
Moves on land by wiggling like a catapillar

42. Family Otariidae (ota-rye-uh-dee)
“Eared Seals”
Sea Lions and Fur Seals
Visible external ears
Flippers are hairless
Hind flippers can be placed under body for awkward locomotion
Longer front flippers

45. Sea Lion vs. Seal

47. Figure 9.09b

48. Odobenidae (Odo-ben-i-de) walruses
CARNIVORA:
Pinnipeds
Odobenidae (Odo-ben-i-de)
walruses
Photo: web

49. CARNIVORA:
Ursidae
polar bears
Photo: web

50. sea otters, weasels, minks, etc
CARNIVORA:
Mustelidae
sea otters, weasels, minks, etc
Photo: web

51. dugongs, Stellar’s sea cows
SIRENIA:
Trichechidae
manatees
Dugongidae
dugongs, Stellar’s sea cows
Photos: web

52. Order Sirenia Includes Manatees and Dugongs “Sea Cows”
Closely related to elephants
Named after sirens from Greek mythology. (mermaids)

53. Sirenians Move by moving tail up and down Well-padded with blubber
A few scattered hairs

54. Sirenians:
only eat seagrasses and other aquatic vegetation
extremely low metabolism
zero tolerance for cold water. 

55. Sirenians are restricted to warm shallow coastal waters, estuaries, and rivers, with healthy ecosystems that support large amounts of seagrass and/or other vegetation.

56. A byproduct of their diet is that Sirenians produce a large volume of gas, which is given off during the digestion of plant material and this makes them particularly buoyant, so much so that their bones are dense in order to compensate

57. SIRENIA: Four living species placed in two families make up this order
Compare that to:
~78 species of cetaceans
~235 species of primates
SIRENIA:

58. Amazonian manatee

59. African manatee

60. West Indian manatee

61. Dugong

63. Thought that the species was likely extinct by 1768.
Extinct Steller’s Sea Cow
Thought that the species was likely extinct by 1768.

64. Hydrodamalis was hunted primarily as a source of food
Hydrodamalis was hunted primarily as a source of food. Steller (1751) describes the meat as being easily prepared and similar to beef in taste and texture.
The blubber was useful for:
cooking
lamp oil.
The milk of harvested cows was consumed directly or made into butter.
The thick, tough hide was used for shoes, belts and to make skin-covered boats.

65. Once known to occur in large herds and have healthy populations , the Amazonian manatee has suffered from extensive hunting by subsistence and commercial hunters

66. Other Threats:
The deforestation of large areas of the forests surrounding this manatee’s river habitats has also caused soil erosion, degradation of food supplies and the reduction of vegetation in the waterway

67. Meanwhile in Florida…..
Watercraft collisions account for approximately 25% of all manatee deaths

71. Anderson (1995) has also noted that the intense hunting of sea otters on the Bering Sea islands may have contributed to the final extinction of Hydrodamalis. It is known that sea urchin populations can severely deplete sea grass and algae communities when otters are removed, and as this happened on the Bering Sea islands, the sea cows would have faced a new competitor for food. A similar course of events may have occurred 12,000-14,000 years earlier along the coast of Asia and North America as aboriginal peoples colonized the areas and began hunting otters and sea cows (Anderson, 1995).