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Marine Mammals

1Picture: G. BearziWHO ARE THEY?

2Photo: webMarine mammalsLand-dwelling ancestorsWarm-bloodedBreathe airHair/furBear live youngMammary glands for milkThey all have 3 ear bones.

Cetacea (se-tay-she-ah)whales, dolphins, and porpoisesCarnivorapolar bears, otters, seals, sea lions, walrusesSirenia (sire-een-e-uh)manatees and dugongs

Three Categories ofMarine Mammals4Photo: webCETACEA: Toothed whales

5Photo: M. Bearzi 2000Bottlenose dolphinStriped dolphinCommon dolphin

6Images: M. DemmaRissos dolphinFocena comuneGlobicephalo...Killer whale

False killer whale

Rough-toothed dolphin

7Images: M. Demma

Rissos dolphinHarbor porpoisePilot whale

8Images: M. Demma

Sperm whale...

Cuviers beaked whale9Images: M. Demma

SPERM WHALE

Not much of a species barrier!11

CETACEA: Baleen whales

15Photo: web

Fin whaleRight whaleSei whaleHumpback whale16Images: M. Demma

CetaceaAdaptations for deep divingUse oxygen efficientlyAbsorb 90% of oxygen inhaled (lots of capillaries)Store large quantities of oxygen (lots of hemoglobin)Reduce oxygen required for noncritical organsDive 10 min (dolphin) to 2 hours (Sperm Whale)Muscles insensitive to buildup of carbon dioxideCollapsible lungsTemperature RegulationBlubber (also for buoyancy and energy storage)Counter-current blood flow warms blood as it returns tocore of bodyMuscles generate heatLow surface area to volumeratio - little surface in contactwith water to lose heat

20Oxygenblowhole (nostrils) on head easierEmpty and fill lungs quickly (2 seconds for a fin whale)Large lungsHigh gas exchange rate (absorb 90% of oxygen - humans absorb 20%)

21OxygenMany red blood cells, hemoglobin carries oxygenmyoglobin - carries additional oxygenShunt blood from non-vital organs (stomach, kidney) when diving to vital organs (brain, heart, muscles)Slow heartbeat rate when diving

22Propulsion Through the WaterStreamlinedInternalized body parts - ear, penis, mammary glands reduces frictionShorter appendages forelimbs for steeringLoss of hind limbsLoss of hair

23

Propulsion Through the Waterfluke (tail) for propulsionUp and down (unlike fish = side to side) surface areaAlso to identify individuals - like fingerprintflippers for steering and balance

25Sensing the EnvironmentGood eyesight but little to no lightecholocation - biological SONAR find and maybe to stun preyVery good hearing - sound travels faster in water than in airex: humpback songs for communication social, territorial

26Cetaceans sensory worldSOUND

Communicationwhistles

Echolocationclicks

27Photo: web

Song of a whaleDolphin whistles

Cetaceans sensory world28Photo: web

Types of WhalesToothed whales suborder OdontocetiBaleen whales suborder Mysticeti29Types of Whales Toothed WhalesHave teeth to catch prey, not chewEat mostly fish and squid - killer whales eat sealsDive deeperMost do not migrateEx:sperm, pilot, killer whales, dolphins, porpoisesEx: sperm whales dive > 3,500 feet for giant squid, up to 75 minutes

30Types of Whales Baleen WhalesNo teeth - 600 - 800 baleen plates to filter krill and other itemsex: blue whale eats 4 tons of krill per dayNot deep diversex: humpback - lung feeding (lunge forward, pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

31Types of Whales Baleen Whalespleats folds under mouthopen like accordion when feeding

32baleenventral groovestonguejaw33Image: from M. Jahoda book, modified FeedingOther whales

34Image: G. Bearzi

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

35Types of Whales Baleen Whalesex:blue, humpback, right, gray, finNorth to feed, south to breed - behavioral adaptationnorth - summer for krillsouth - winter to raise youngex: gray whales, 3 monthmigration, Arctic to Baja, CA,6,000 mi one way

36Order CarnivoraPinnipeds (large skin covered flippers)WalrusesSeals Sea lionsFur seals

CARNIVORA: Pinnipeds

Otariidae sea lions, fur seals, etc

Phocidaetrue seals

38Photos: M. Bearzi 2000Family Phocidea (Pho-ce-die)True or Earless SealsNo external earsFlippers covered in furHind flippers cannot be turned forward under the body for use in terrestrial motionMoves on land by wiggling like a catapillar

Family Otariidae (ota-rye-uh-dee)

Eared SealsSea Lions and Fur SealsVisible external earsFlippers are hairlessHind flippers can be placed under body for awkward locomotionLonger front flippers

Sea Lion vs. Seal

Figure 9.09b

CARNIVORA: PinnipedsOdobenidae (Odo-ben-i-de)walruses

48Photo: web

CARNIVORA: Ursidaepolar bears

49Photo: web

CARNIVORA: Mustelidaesea otters, weasels, minks, etc

50Photo: web

SIRENIA:

Trichechidaemanatees

Dugongidaedugongs, Stellars sea cows

51Photos: web

Order Sirenia

Includes Manatees and DugongsSea CowsClosely related to elephantsNamed after sirens from Greek mythology. (mermaids)SireniansMove by moving tail up and downWell-padded with blubberA few scattered hairs

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

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

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

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

Amazonian manatee

African manatee

West Indian manatee

Dugong

Thought that the species was likely extinct by 1768.Extinct Stellers Sea CowHydrodamaliswas 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.Once known to occur in large herds and have healthy populations, the Amazonian manatee has suffered from extensive hunting by subsistence and commercial hunters

Other Threats:The deforestation of large areas of the forests surrounding this manatees river habitats has also caused soil erosion, degradation of food supplies and the reduction of vegetation in the waterwayWatercraft collisions account for approximately 25% of all manatee deaths

Meanwhile in Florida..

http://live.wsj.com/video/mellow-manatees-at-the-center-of-a-storm/001901E5-5BC5-4544-8D2B-C17A9D74119B.html#!001901E5-5BC5-4544-8D2B-C17A9D74119BAnderson (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).