Marine Mammals: Part 1

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Marine MammalsPart 1

• Marine Vertebrates Lecture 7

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(No Transcript)
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Class Mammalia Key characteristics

• Mammary glands (milk production)
• Hair
• Endothermic
• Efficient circulatory system (4-chambered heart)
• Efficient respiratory system (diaphragm)
• Internal fertilization
• Relatively large brains
• Differentiation of teeth
• Development of malleus and incus in middle ear
  (reptiles already have stapes)

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Order Carnivora

• Ursidae polar bears
• Mustilidae sea otters

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(Sub)order Pinnipedia

• Phocidae
• Otariidae
• Odobenidae

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Order Sirenia

• Manatees and dugongs

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Order Cetacea

• Suborder Odontoceti
• Suborder Mysticeti

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Osmotic balance

• Acquiring water
• Diet
• Drink
• Metabolically-produced water
• Water loss
• Skin, sweat glands, exhalation
• Excretion of water and ions
• Kidneys
• Concentrating ability mirrors reptile/bird salt
  glands

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Thermoregulation

• Heat retention Fur vs. blubber
• Dry fur is a more efficient insulator than
  blubber
• Specializations of marine mammal fur
• Fur seals and sea otters
• Polar bears
• Regulation of heat via blood flow changes
• Regulating flow to capillary beds
• Esp. hairless regions of body
• Countercurrent exchange
• Large size and shape
• Surface to volume low
• Comparison to land mammals

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Order CarnivoraFamily Ursidae
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Adaptations to marine existence

• Streamlining
• No prominent shoulder humps
• Small head small ears
• Adaptations for swimming
• Paws are larger, partly webbed
• Also allows for more even distribution of weight
  on ice
• Long neck (how of value?)
• Dog paddle!
• Thermoregulation
• Thicker fur
• Clear, hollow guard hairs
• These may actually absorb ultraviolet light)
• gt2x the size of grizzlies (up to 1800 pounds)

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Habitat/Feeding ecology

• Circumpolar distribution
• Stable, but not continuous, (mostly) annual pack
  ice
• Cant find prey without
• Seal specialists will also hunt other marine
  mammals
• Follow leads or finding holes made by their prey.
• Male vs. female foraging
• Males venture further out onto less-stable pack
  ice
• Avoid the most unstable ice near the ice edge ?
  ideal pupping grounds for seals
• Females remain on more-stable pack ice closer to
  den sites.
• Locate ringed seal pups in dens beneath snow or
  in small ice caves in the pack ice
• Use their sense of smell

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Life History

• Mating
• April/May
• 31 MaleFemale operational sex ratio (Why?)
• Induced ovulation
• Delayed implantation
• Maternity dens ( mid-October)
• Young born in December/January Young are 1-1.5
  pounds at birth!
• Usually two.
• Break out of dens ( March/April)
• Young 25-30 pounds
• Female is hungry
• Cubs with mother for 2.5 years

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Conservation status Threatened

• Key threats
• Habitat loss
• Global climate change
• Harvesting
• Water pollution

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Order CarnivoraFamily Mustilidae sea otters!
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Overview/adaptations to marine existence

• Size quite small for a marine mammal
• 45-65 pounds
• Dive stats 120 feet 4 minutes breath-hold
• Thermoregulation (water is 30-50?F)
• Fur
• High metabolic rate (25 of body weight per day)
• Swim on their backs
• Use webbed hindflippers in an alternate motion
  for propulsion also use their flattened tail.
• Relatively slow for marine mammals, 2-3 kt
  cruising speed.
• Forelimbs are very mobile, resemble arms and
  hands for collecting/manipulating food

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Habitat/feeding ecology

• Live in kelp forests
• Wrap themselves and their young in the kelp...
• Feed on a wide variety of benthic invertebrates
• sea urchins, abalone, crabs, sea stars, clams,
  scallops, etc
• May play important role in maintenance of kelp
  beds
• Tool users (bang creatures with exoskeletons,
  shells, and even endoskeletons on rocks)
• Kelp itself provides some protection from
  predation.

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Sea otter Historic distribution
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Sea otter Current distribution
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Conservation status Endangered

• CA sea otter population steady, some slow growth
• AK (Aleutian Islands) huge decline
• Orca predation
• Major threats
• Coastal pollution
• Oil spills
• Cat litter and Toxoplasma gondii
• Decline of other marine mammals