1. Marine Mammals

3. Mammals have returned to the oceans multiple times
Return to the Oceans
Mammals have returned to the oceans multiple times
Adaptations
vivipary
suckling young
thermoregulation
feeding
diving
osmoregulation
Osmoregulation in marine mammals has been investigated for over a century; however, a review of recent advances in our understanding of water and electrolyte balance and of renal function in marine mammals is warranted. The following topics are discussed: (i) kidney structure and urine concentrating ability, (ii) sources of water, (iii) the effects of feeding, fasting and diving, (iv) the renal responses to infusions of varying salinity and (v) hormonal regulation. The kidneys of pinnipeds and cetaceans are reniculate in structure, unlike those of terrestrial mammals (except bears), but this difference does not confer any greater concentrating ability. Pinnipeds, cetaceans, manatees and sea otters can concentrate their urine above the concentration of sea water, but only pinnipeds and otters have been shown to produce urine concentrations of Na+ and Cl-1 that are similar to those in sea water. This could afford them the capacity to drink sea water and not lose fresh water. However, with few exceptions, drinking is not a common behavior in pinnipeds and cetaceans. Water balance is maintained in these animals via metabolic and dietary water, while incidental ingestion and dietary salt may help maintain electrolyte homeostasis. Unlike most other aquatic mammals, sea otters commonly drink sea water and manatees frequently drink fresh water. Among the various taxonomic groups of marine mammals, the sensitivity of the renin–angiotensin–aldosterone system appears to be influenced by the availability of Na+. The antidiuretic role of vasopressin remains inconclusive in marine mammals, while the natriuretic function of atrial natriuretic peptide has yet to be examined. Ideas on the direction of future studies are presented.

4. Marine mammals Characteristics of marine mammals: Warm-blooded
Breathe air
Have hair (or fur)
Bear live young
Females have mammary glands that produce milk for their young

5. Fusiform Shape and Streamlining Evolutionary Convergence

6. Adaptations for diving
Exchange a large amount of air on each breath
Up to 90% in each breath (humans exchange about 20%)
Blood with more oxygen carrying capacity
Heart rate slows
Blood flow shunted
Higher concentration of myoglobin in the muscles
Collapsing lungs
Dive with no air in contact with blood vessels to avoid problems of nitrogen being forced in

7. Two basic bioenergetic strategies used by animals :
Endothermy “warm blooded”
Ectothermy “cold blooded”

8. Countercurrent Exchange
Concurrent exchange
Countercurrent exchange

9. Osmoregulation (water balance)
Marine Mammals have highly efficient kidneys capable of producing very hypertonic urine.
These animals also rely on metabolic water and water from feeding on fishes and invertebrates.
Unlike most other aquatic mammals, sea otters commonly drink sea water and manatees frequently drink fresh water

10. Marine mammals: Order Sirenia
Sirenian characteristics:
Large body size
Sparse hair all over body
Vegetarians
Toenails (on manatees only)
Includes:
Manatees
Dugongs

11. Manatee & Dugong
Most complete transition to marine life along with whales and dolphins
Related to the elephant, but common ancestor didn’t look like either of them
Once many more species around
Large layer of blubber
Origin of the mermaid myth
Herbivores
Nostrils on top of snout have valves to keep water out
Both species have one calf at a time
Tend to have a single calf every 3 years
Description & Fascinating Facts The Dugong, Dugong dugon, range in length from m in length. Sexual dimorphism is either absent or females may slightly outsize males and can weigh over 270 kg. Dugongs are born a pale cream color, but they darken with age to a deep slate gray dorsally and laterally. Short hair is sparsely distributed over the body, save the bristles on the muzzle. The skin is thick, tough and smooth. The front-limbs have evolved into flippers that are cm long. These are used for propulsion by young, but the adults use the fluke-like tail for locomotion, using the flippers for steering. The muscular upper lip is cleft and protrudes over the down turned mouth. The premaxilla is enlarged and downturned, the nasal bones are absent, the braincase is small and the zygomatic arch is thick and deep. The bones of the skeleton are pachyostotic (extremely thickened and dense). Although superficially they resemble whales, sirenians have evolved independently. They are descended from the group of ancient land mammals that also gave rise to the elephants. World Range & Habitat Pacific Ocean, Indian Ocean: Found discontinuously in coastal waters of east Africa from the Red Sea to northernmost South, northeastern Indian, along the Malay peninsula, around the northern coast of Australia to New Guinea and many of the island groups of the South Pacific. Range was much greater in the past. Dugongs inhabit shallow, tropical marine coastal water mainly confined to sea grass beds, which occur in calm and shallow coastal areas, such as embayment and lagoons. Dugongs and are more strictly marine than manatees, it seldom enters rivers. Feeding Behavior Dugongs feed on the phanerogamous (having visible flowers containing distinct stamens and pistils) sea grasses of the families Potamogetonaceae and Hydrocharitaceae. Also reported to occasionally eat algae, and crabs have also been found in the stomachs of dugongs. Despite its diet, the dugong has a relatively simple stomach. The lower lip and distal parts of the palate have horny pads used to grasp vegetation, which is then uprooted with the strong upper lip. Dugongs have teeth in adults. The molars are rootless, circular in cross-section and lack enamel, males have long, tusklike incisor teeth. Reproduction The Dugong is a long-lived animal with a life span of up to 70 years, a minimum pre-reproductive period of 9-10 years, though it can occur as late as 15 years and an estimated mean calving interval of 3-7 years. Breeding occurs throughout the year and peak months for birth vary geographically. The exact length of gestation is unknown, but it is presumed to be about 1 year. Single calves are the norm and twins are rare. Parturition (the birth process)takes place in shallow water, and newborn calves are able to swim immediately to the surface for their first breath of air. Newborn calves are about cm long and weigh kg. Young may remain with the mother for a year. Warnings & Comments Dugongs are hunted throughout their range for meat, which has been likened to veal. They are also hunted for oil, hides for leather, and for their bones and teeth, which are made into ivory artifacts and charcoal for sugar refining. Some Asian cultures prize dugong products for medicinal purposes. Has been heavily exploited in the Philippines, almost to extinction. Endangered. Dugongs have a good fossil record going back to Eocene terrestrial ancestors.

12. Dugong
Location: coastal and inland waters of the western Indo-Pacific region
Dugongs are exclusively marine and have a dolphin-like tail
Dugongs tend to dig seagrass rhizomes
Predator includes tiger sharks

13. 10,000
Dugong Range

14. Family Dugongidae Dugong dugong Steller's Sea Cow tHydrodamalis gigas
Discovered 1741.
8.9 ft, lbs
At one time, the Steller's sea cow was found in the cold waters of the Bering Sea, but it was hunted to extinction within 27 years of its discovery in The largest sirenian on record, the Steller's sea cow grew up to nine meters (30 feet) in length and weighed around four metric tons (approximately 4.4 tons).
30ft, 4.4 tons

15. Manatee Location: Florida, Central and South America
Manatees have paddle-like tails and frequent freshwater
Manatees tend to crop and grab with prehensile lips
Manatees are larger than dugongs
Few predators
Threats:
Careless boaters
Habitat loss

16. Manatee
9.8 ft, lbs
3,000 in U.S.

17. Relationship between Sirenians and elephants (mtDNA)
Asian elephant
African elephant
tmammoth
tmastadon
tStellar’s sea cow
Dugong
Ancestral
mammals
West Indian manatee
Brazilian manatee
West African manatee
Other mammals 80 60 40 20
Million of years before present

18. Marine mammals: Order Carnivora
All members of order Carnivora have prominent canine teeth
Includes:
Sea otters
Polar bears
Pinnipeds (flipper-footed)
Walrus
Seals
Sea lions/fur seals
Hawaiian Monk Seal

19. Sea Otter

20. Sea Otter Enhydra lutris Native to north Pacific 394,000 hairs/cm2
No blubber
Female 45 lbs; Male 65lbs
Diet: Sea urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species.
Uses tools
Dives to 330 ft
Rests in coastal kelp forests
STATUS: California, or southern, sea otters are listed as "threatened" under the federal Endangered Species Act (ESA) and "fully protected" under California state law. No other U.S. otter population is currently listed under the ESA. In 2003, there is a push to list a stock of the Alaskan sea otters, or northern sea otters, as "endangered" under the ESA. In Canada , the otter population in British Columbia is classified as "threatened" by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). All of the otters in the U.S. are protected under the U.S. Marine Mammal Protection Act (MMPA). DESCRIPTION: The sea otter has the thickest fur in the animal kingdom. Unlike other marine mammals, the sea otter does not have a layer of blubber (fat) to help keep it warm. If an otter's fur gets coated with oil or any other substance, it can easily die from cold and exposure.
SIZE: The sea otter is the largest member of the weasel family. Southern sea otters typically reach about four feet in length. Females average 45 pounds, while males average 65 pounds. Northern sea otters can reach up to 100 pounds.
POPULATION: Today there are about 2,500 southern sea otters off the coast of California. There are between 27,500 and 52,500 northern sea otters residing in Alaska, Canada and Washington. There are approximately 15,000 in Russia. Two hundred years ago, demand for the otter's pelt nearly led to its extinction.
LIFESPAN: Male sea otters live an average of ten to 15 years, while female sea otters live an average of 15 to 20 years.
RANGE: The sea otter?s historic range stretched from Japan, along the coast of Siberia and the Aleutian Chain and down the Alaska, British Columbia, Washington, Oregon and California coast to Baja California.
HABITAT:Shallow coastal waters of the northern Pacific.
FOOD:Sea urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species.
BEHAVIOR: Sea otters are the only mammals other than primates known to use tools. Otters use small rocks or other objects to pry prey from rocks and to hammer or pry open their food. They can dive up to 330 feet when foraging for food. Otters rest in coastal kelp forests, often draping the kelp over their bodies to keep from drifting away.
OFFSPRING: Sea otters breed throughout the year. Females give birth to one pup after a gestation period of six to eight months.
THREATS: Oil spills, habitat loss, disease, gill net entanglement and conflict with shellfish fisheries.
PROTECTION: *CITES, Appendix I, Marine Mammal Protection Act, Endangered Species Act
*Convention on International
The Sea Otter (Enhydra lutris) is a large otter native to the North Pacific, from northern Japan and Kamchatka east across the Aleutian Islands south to California. The heaviest of the otters, Sea Otters are the only species within the genus Enhydra.
Hunted extensively for their luxurious fur—the densest of all mammals with up to 394,000 hairs per square centimeter— from 1741 onwards, sea otter populations were greatly reduced to the point of extermination in many parts of their historic range. By 1911 the world population was estimated to be just 1,000-2,000 individuals in 13 colonies. Its estimated that a half million to a million otters were killed over time and over hunted and the population is thought to have been 150,000 to 300,000 historically before the years of the great hunt. Although several subspecies are still endangered, the otters have since been legally protected, and reintroduction efforts have shown positive results in some areas.

21. Polar Bear
Pop size: 22,000 to 27,000
Weight: 550 to 1,700 pounds

22. Polar Bear Ursa maritimus
United States, Canada, Russia, Greenland and on the Arctic islands of Norway
Male: 10 feet tall and weigh over 1400 lbs
Female: seven feet and weigh 650 lbs
wild polar bears live up to age 25.
Not federally listed as endangered or threatened. The International Union for Conservation of Nature (IUCN), Polar Bear Specialist Group lists most populations as "stable." DESCRIPTION: The polar bear rivals the Kodiak bear as the largest four-footed carnivore on Earth and can live up to 25 years. Although the polar bear?s coat appears white, each individual hair is actually a clear hollow tube that channels the sun?s energy directly to the bear?s skin and helps it stay warm. The polar bear?s entire body is furred, even the bottom of its paws. That helps prevent bears from slipping on the ice. The polar bear is classified as a marine mammal. Its feet are partially webbed for swimming, and its fur is water-repellent. A formidable predator, it has extremely sharp claws.
SIZE: Males are 8 to 11 feet long and weigh 500 to 1,100 pounds but can reach as much as 1,500 pounds. Females are smaller, measuring 6 to 8 feet long, and weigh from 350 to 600 pounds, occasionally reaching 700 pounds.
POPULATION: Worldwide there are thought to be 22,000-27,000 polar bears in 19 separate populations. They can be found in the United States, Canada, Russia, Greenland and on the Arctic islands of Norway. There are estimated to be about 3,000 to 5,000 polar bears in Alaska.
RANGE:Polar bears are found throughout the Arctic and are the most nomadic of all bear species. They travel an average of 5,500 miles a year or 15 miles a day. In the United States, polar bears are located in two Alaskan populations: the Chukchi/Bering Seas of western Alaska and the Beaufort Sea off northern Alaska.
HABITAT: The entire circumpolar Arctic region is polar bear habitat. They are equally comfortable in the water and on land. Polar bears can be found on pack ice, coastal islands, coastlines and even out in Arctic waters. They are exceptional swimmers and have been observed in the sea more than 100 miles from the nearest land or pack ice.
FOOD: Polar bears are strictly carnivores and feed or scavenge only meat. Their primary prey is the ringed seal though they also take bearded, harp and hooded seals and the occasional walrus youngster. They will also scavenge walrus and whale carcasses. That sometimes results in temporary aggregations of polar bears at such sites. Other species, such as the Arctic fox, rely entirely upon "polar bear left-overs" after the bears have eaten their fill of seal skin and blubber, leaving the remaining meat for such scavengers.
BEHAVIOR: The two main focuses of this solitary creature's life are to conserve energy and to hunt. Only pregnant females dig dens and hibernate in the traditional sense for extended periods. The other bears may enter into what is referred to as "walking hibernation" where they remain active and continue to hunt and feed, even though some of their metabolic processes may slow (decreased heart rates, respiration, lowered temperatures, etc.). Polar bears depend mostly on their sense of smell to determine the location of prey. Their white coats make great camouflage for hunting seals, and they will wait patiently for hours next to a seal?s air hole waiting for the seal to take a breath. Once the seal arrives, the polar bear will use its immense strength and sharp claws to clutch the seal and drag it through the small blowhole.
OFFSPRING: Females are able to breed at the age of five years. They dig dens either on the coastal mainland or out on the drifting pack ice in late October or early November, and then remain denned until the next spring. An average of two cubs are born, each weighing about 1 pound at birth and growing to about 15 pounds by the time they emerge in the spring. The cubs have much to learn and usually remain with their mothers for more than two years.
THREATS:
The primary threat facing polar bears today may be global warming. Scientists have already documented measurable effects in the body sizes and reproductive success of bears at Hudson?s Bay. This southern-most population of polar bears has adapted to an ice-free summer by moving onshore at Churchill, Manitoba, and fasting through the short summer season until freeze-up occurs, and the bears can return to the ice. Global warming has resulted in prolonged ice-free periods, and the polar bears are left stranded onshore for longer and longer periods. Break-up in the spring occurs an average of days earlier than 20 years ago and was four weeks earlier in Scientists estimate that for every week of delay in freeze-up, polar bears lose at least 22 pounds of critical fat reserves. Pregnant females are losing so much weight that they fail to produce enough milk for their cubs, which then suffer increased mortality. Once females fail to attain a minimum weight they won?t give birth at all, and scientists can already document a 15 percent drop in birth rates.
Another globally produced impact to polar bears are chemical pollutants that find their way into the cold Arctic ecosystems and then never disappear. Such chemicals as PCB?s (polychlorinated biphenyls), banned from the U.S. plastics industry since the 1970s, concentrate in the blubber of prey species that are then eaten by the bears. Such concentrations of these and other toxins are linked to immune deficiencies and generally reduced fitness in some polar bears.
The third threat of note is the proposed oil and gas development on the Arctic National Wildlife Refuge in northeastern Alaska. This is the most important onshore denning habitat for polar bears in the United States. About half of the bears from the Beaufort Sea population den onshore, and half of these select the refuge?s coastal plain. This is the very place proposed for oil exploration. Both the seismic exploration phase and an eventual oil extraction phase could introduce serious disturbances that may result in den abandonment and death of the offspring.
PROTECTION: CITES* Appendix II, U.S. Marine Mammal Protection Act, Agreement on the Conservation of Polar Bears.
Good swimmers
Thick blubber
Thick fur

23. Polar bears
Polar bears are the least adapted to the marine lifestyle
Land animals that are adapted to the cold
Considered marine mammals because they feed almost exclusively on marine organisms
Very good swimmers, but can’t dive below surface well
Hunt seals and walruses, occasionally cetaceans

24. Range depends on sea ice
Circumpolar in Arctic
Range depends on sea ice
normal range          occasional range over pack occasional range over permanent ice

25. (Latin for winged-foot)
Pinnipeds
(Latin for winged-foot)

26. Pinnipeds Hawaiian Monk Seal Family Phocidae Walrus Sea Lion
Family Odobenidae
Family Otariidae

27. Biology and Natural History
Order Pinniped (seals, sea lions, & walruses)
Family Phocidae- true, earless seals
Family Otariidae- eared seals and sea lions
Family Odobenidae- walruses
34 known species
Evolved 20 mya from Order Carnivora (ancestors of dogs and bears)
Differ in possession of external ears and mode of locomotion

28. Differences between seals and sea lions/fur seals

29. Hind flippers propel them while swimming Front flippers act as rudders
Hawaiian Monk Seal
Family Phocidae
Lack external ears
Hind flippers propel them while swimming
Front flippers act as rudders
Travel on land is difficult (wiggle)

30. Front flippers propel animal when swimming
Sea Lion
Family Otariidae
Eared seals
Front flippers propel animal when swimming
Rear flippers act as rudders
Fairly mobile on land

31. Paddle with front flippers Rear flippers act as a rudder
Walrus
Family Odobenidae
Found in Arctic region
Lack external ears
Paddle with front flippers
Rear flippers act as a rudder
Fairly mobile on land

32. Walrus Range Map
                                                      
Pacific walrus is in lavender, Atlantic walrus is in rose.

33. Walrus Facts Location:
Bering sea, Pacific Ocean, Atlantic Ocean, Arctic Ocean
Pop Size:
250,000
Size:
Weight: 2,000-3,500 lb.
Breeding:
Sexually mature late
females, usually 6-7 years
males, 15 years.
Produce few offspring
                                                                                        

34. Walrus Facts Lifestyle Habit: Gregarious, living mainly in herds.
Diet: Benthic suction feeders. Feed mainly on bivalve mollusks, but also other invertebrate marine animals, fish, sometimes seals and whales.
Predators: polar bears, killer whales, and humans
Lifespan: Up to 40 years.

35. Walrus Facts Swim speed: 7-35 kph Tusks: Both male & female
Used for dragging body across land or ice
Symbolize age, sex, and social status
Pharyngeal pockets:
2 found on either side of the esophagus that hold up to 50 liters of air ).
For buoyancy; these pockets facilitate sleep in the water in an upright position
May be used to amplify mating calls

36. Whales, Dolphins, & Porpoise

37. Pakicetus attocki
Age: Early Eocene, 50 million years old
Location: Pakistan

38. Whale Evolution

39. Ambulocetus natans in action
Ambulocetus natans in action. A reconstruction of an early close cousin of whales.

40. Marine mammals: Order Cetacea

41. Marine mammals: Order Cetacea
Cetacean characteristics:
Blowholes on top of skull
Skull telescoped (streamlined shape)
Very few hairs
Includes:
Whales, dolphins, and porpoises

42. Two suborders of order Cetacea
(55 mya- entered sea)
Suborder Odontoceti (toothed whales)
Echolocate (send sound through water)
Includes killer whale, sperm whale, dolphins, porpoises, and many others
Suborder Mysticeti (baleen whales)
Have rows of baleen plates instead of teeth
Includes blue whale, finback whale, humpback whale, gray whale, and many others

43. Differences between Odontocetes and Mysticetes
Anatomical Toothed Baleen
Features whales whales
Symmetry of skull Asymmetrical Symmetrical
Feeding structures Teeth Baleen
Stomach divisions Three to 13 Always three
External blow holes One Two
Digits in hand Five Four (five in right whales)
Wax ear plug Not present Present
Hair Present in fetus Always present on adults
Larger sex Males largest Females largest
Food Squid, fish Plankton, small fish

44. Differences between dolphins and porpoises
Dolphins have:
An elongated snout (rostrum)
A sickle-shaped (falcate) dorsal fin
Conical-shaped teeth
Killer whale jawbone

45. Differences between dolphins and porpoises
Porpoises have:
A blunt snout (rostrum)
A triangle-shaped dorsal fin
Spade-shaped teeth

46. Echolcation - the location of objects by their echos - is a highly specialized faculty that enables dolphins to explore their environment and search out their prey in a watery world where sight is often of little use. As sound travels four and a half times faster in water than in air, the dolphin's brain must be extremely well adapted in order to make a rapid analysis of the complicated information provided by the echoes. Although the ability to echolcate has only been proven experimentally for a few odontocete species, the anatomical evidence - the presence of the melon, nasal sacs and specialized skull structures - suggests that all dolphins have this ability.
The dolphin is able to generate sound in the form of clicks, within its nasal sacs, situated behind the melon. The frequency of this click is higher than that of the sounds used for communication and differs between species. The melon acts as a lens which focuses the sound into a narrow beam that is projected in front of the animal.
When the sound strikes an object, some of the energy of the soundwave is reflected back towards the dolphin. It would appear that the panbone in the dolphin's lower jaw receives the echo, and the fatty tissue behind it transmits the sound to the middle e ar and thence to the brain. It has recently been suggested that the teeth of the dolphin, and the mandibular nerve that runs through the jawbone may transmit additional information to the dolphin's brain.
As soon as an echo is received, the dolphin generates another click. The time lapse between click and echo enables the dolphin to evaluate the distance between it and the object; the varying strength of the signal as it is received on the two sides of th e dolphin's head enable it to evaluate direction. By continuously emitting clicks and receiving echoes in theis way, the dolphin can track objects and home in on them.
The echolocation system of the dolphin is extremely sensitive and complex. Using only its acoustic senses, a bottlenose dolphin can discriminate between practically identical objects which differ by ten per cent or less in volume or surface area. It can do this in a noisy environment, can whistle and echolocate at the same time, and echolocate on near and distant targets simultaneously - feats which leave human sonar experts gasping

47. Echolcation - the location of objects by their echos - is a highly specialized faculty that enables dolphins to explore their environment and search out their prey in a watery world where sight is often of little use. As sound travels four and a half times faster in water than in air, the dolphin's brain must be extremely well adapted in order to make a rapid analysis of the complicated information provided by the echoes. Although the ability to echolcate has only been proven experimentally for a few odontocete species, the anatomical evidence - the presence of the melon, nasal sacs and specialized skull structures - suggests that all dolphins have this ability.
The dolphin is able to generate sound in the form of clicks, within its nasal sacs, situated behind the melon. The frequency of this click is higher than that of the sounds used for communication and differs between species. The melon acts as a lens which focuses the sound into a narrow beam that is projected in front of the animal.

48. Echolocation
Sensing environment
Produce clicks that travel out, hit objects and reflect back
Produced by a structure in the airway called the “monkey lips”
Sound received through the lower jaw
Low frequency clicks travel further but can only be used for big objects
High frequency clicks can discriminate small objects but don’t travel as far

49. Deepest Diver
(3km~1.5 miles)

50. Mysticeti: The baleen whales
Mysticeti whales have baleen instead of teeth
Baleen plates:
Hang as parallel rows from the upper jaw
Are made of keratin
Are used as a strainer to capture zooplankton
Allows baleen whales to eat krill and small fish by the ton

51. Baleen

52. Types of baleen whales Baleen whales include three families:
Gray whale (a bottom-feeder with short baleen)
Rorqual whales (medium-sized baleen)
Balaenopterids (blue whales, finback whales, and other large whales )
Megapterids (humpback whales)
Right whales (surface skimmers with long baleen)

53. Whale Migration