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BIO2242 > Lecture 24 - Water Mammals > Flashcards

Lecture 24 - Water Mammals Flashcards

1
Q

What are some of the major adaptations made by tetrapods to adapt to life on land?

A 
ability to walk
breathing air
amniotic egg/live birth
different thermoregulation
hearing airborne sounds
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2
Q

What are the problems with returning to the water for tetrapods?

A
  • Buoyancy
  • Slow and inefficient
  • Can’t breathe
  • Lose heat faster
  • Won’t be able to smell, see, or hear
  • Can’t eat without swallowing sea water
  • Pressure (the bends)
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3
Q

How many different times have marine tetrapods colonised the ocean?

A

30 times throughout history

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4
Q

How is a terrestrial vertebrates Buoyancy a problem underwater?

A

They are too buoyant

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5
Q

How do dugongs and other marine mammals overcome the issue of being to buoyant?

A

Dense bones

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6
Q

What advantage does returning to the water bring?

A

taking advantage of open niches(usually the lack of large species)

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7
Q

How did marine tetrapods make themselves faster and more efficient underwater?

A

evolution of Hydrodynamic forms. Includes streamlined bodies, flippers rather than hands or wings and the loss or reduction of hindlimbs

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8
Q

How do marine tetrapods prevent heat loss?

A

Insulating fur, feathers, blubber and Counter-current heat exchange

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9
Q

What are the groups of marine mammals?

A 
Cetaceans
       - Mysticetes: Baleen whales
       - Odontocetes: Toothed Whales
Pinnipeds
       - Phocids: True seals
       - Otariids: Fur seals and sea lions
       - Odobenids: Walruses
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10
Q

What order are Cetaceans from?

A

Artiodactyl: Even-toed ungulates

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11
Q

What are Archaeocetes?

A

Ancient whales

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12
Q

What order are Pinnipeds from?

A

Carnivora

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13
Q

Can whales smell?

A

No, the mammalian sense of smell does not work underwater so whales have lost it.

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14
Q

When Transitioning to Life in Water, What Features did Marine Mammals Initially Evolve?

A
  • Initially evolved larger eyes.
  • Eye size (and orbit) now varies
  • Relied more on their sense of touch (e.g. - whales use sensory organ on their jaw, seals use undulating whiskers to detect fine movement in water)
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15
Q

Why do Marine Mammals Need to Hear in Water?

A

Ideally to communicate with others (e.g. - mating, finding other members of same species) and to locate prey (hunting).

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16
Q

How do Terrestrial Mammals Hear in the Air?

A
  • Air-filled passages and chambers

- Ear drum only vibrates in response to sound travelling through air.

17
Q

What is the Direction of Travel of Sound Energy for Terrestrial Mammals?

A

Ear canal > ear drum > middle ear bones > oval window > inner ear (cochlea) > round window

18
Q

How do Marine Mammals Hear Underwater?

A
  • Whales hear via fat pads in their mandibles
  • Toothed whales use echolocation (clicking sounds via blowhole and picked up by fat pads)
  • Pinnipeds can hear in air and underwater through the use of a tissue called the cavernous sinus lines (fill with blood when seals dive to match density of water).
19
Q

What are Some Issues Marine Mammals Face When Hunting Prey?

A
  • Modified senses to detect prey
  • Hydrodynamic body forms to catch up to prey
  • Altered anatomy and physiology to hold breath (e.g. - extra haemoglobin and collapsed lungs)
  • How would they eat their prey once caught?
20
Q

What are the Six Feeding Strategies for Aquatic Mammals?

A
  1. Terrestrial feeding
  2. Semi-aquatic feeding
  3. Aquatic “raptorial” feeding
  4. Suction feeding
  5. Suction filter feeding
  6. Ram filter feeding
21
Q

Explain the Process of Terrestrial Feeding:

A
  • Capture prey using teeth and claws
  • Consume prey on land (in air)
  • Often using sharp cutting teeth
22
Q

Explain the Process of Semi-Aquatic Feeding:

A
  • Prey is separated from seawater
  • Can still breathe
  • Can break apart (process) prey
23
Q

Explain the Process of Aquatic “Raptorial” Feeding:

A
  • Swim until prey is in jaws (ram)
  • Snap mouth shut, trapping prey between teeth
  • Swallow prey whole
24
Q

Explain the Process of Suction Feeding:

A
  • Generate suction by opening mouth and moving tongue
  • Suction feeders sometimes have non-functional teeth
  • Once prey is in mouth, need to remove seawater
25
Q

Explain the Process of Suction Filter Feeding:

A
  • Suck in mouthful of small prey
  • Expel water through fine sieve to trap prey inside mouth
  • Specialised filtering apparatus used to filter out small prey
26
Q

Explain the Process of Ram Filter Feeding:

A

Two Strategies:

  1. Skimming: Swim slowly through the water collecting tiny zooplankton in fine baleen sieve.
  2. Lunge Feeding: Swim fast toward prey and engulf huge volume of water along with evasive prey like fish and krill

BIO2242 (33 decks)

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