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BSC Zoology - Australian Wildlife > Lecture 14- Monotremes I (platypus) > Flashcards

Lecture 14- Monotremes I (platypus) Flashcards

1
Q

What is the classification of a platypus?

A
  • Subclass: Prototheria
  • Order: Monotremata
  • Family: Ornithorhynchidae
  • platypus= 1 species
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2
Q

What are the 6 characteristics that are special about the platypus?

A
  1. cloaca (one hole)
  2. lay eggs
  3. lactate
  4. electroreception
  5. low Tb compared to other mammals
  6. reptilian pectoral girdle (walk in a push up position, legs not below the body)
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3
Q

What does the pectoral girdle mean in platypus?

A

-cannot move as fast on land

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4
Q

What does it mean that fossils of platypus were found far inland in Australia?

A

used to have forests inland, with permanent water

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5
Q

Why are there few echidna fossils?

A

-don’t have teeth and the ancestors didn’t either so not preserved

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6
Q

Why is there lot of platypus fossils around?

A

-ancestors of platypus had teeth and those are more easily fossilised

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7
Q

How old are the oldest fossils of platypus?

A
  • 120MY
  • early Cretaceous
  • must have existed before that, overlapped with dinosaurs
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8
Q

Do today’s platypus have teeth?

A

-no, born with them but these drop quite early on

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9
Q

Where are the monotremes today?

A

-Australia and PNG

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10
Q

Are monotremes Gondwanan?

A

-Yes, found fossil in Patagonia (60MY old)

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11
Q

What are the skulls of the modern platypus and the ancient one like?

A
  • obdurodon species (ancient) were larger, had teeth, extinct about 25MYA)
  • today’s Ornithorhynchus anatinus is smaller and no teeth
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12
Q

What is the modern distribution of the platypus?

A

On the east coast of Australia, abundant, not affected too much by european settlement

  • cannot live in too high temperatures (38C and above) so global climate change could pose harm to it
  • alpine to sea level, north Qld to Tas
  • need permanent water
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13
Q

What is the habitat of the platypus?

A
  • permanent lakes and streams, including estuaries (but not marine environments)
  • the water can be shallow or deep
  • swim near the surface
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14
Q

What are the functions of the burrows platypus dig? (4)

A
  1. resting
  2. predator avoidance
  3. avoidance of temperature extremes
  4. safe environment for raising young
    - use multiple burrows, the ones for young are deeper
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15
Q

Where does the platypus live most of the day and when is it active?

A

live in water for half a day, rest during the day

  • nocturnal typically
  • sometimes also active diurnally
  • problem with flooding= babies washed out
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16
Q

When do platypus forage?

A

-from dusk to dawn

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17
Q

What do platypus eat and where do they find it?

A
  • mainly eat aquatic invertebrates

- forage mainly on the stream bed

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18
Q

How do platypus catch their prey?

A

-use electro- and mechanoreceptors to locate their pray
(eyes and ears are closed under water)
-crayfish= have high lipid content
-crayfish when escaping, tail flip= any movement of the animal= contraction of the muscle= electricity= platypus can detect(can detect very small signals, like 2-3 cm big larvae)

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19
Q

Do platypus have teeth?

A
  • adult platypus don’t have true teeth
  • have horny plate can exert lot of pressure
  • store small prey in cheek pouches and surface to chew
  • when attacking crayfish hit and retreat so they don’t get caught by the claw/pincer
20
Q

How much food does a platypus eat a day?

A
  • about 1/3 of its bodyweight

- up to 1/2 of its bodyweight

21
Q

Where do platypus store their fat?

A

-in their tail

22
Q

How can you tell if a platypus is in good shape?

A

-by the feel of the tail and how much fat there is

23
Q

How does the male platypus distribution of fat change during the year?

A

-low during breeding season (July to September)

24
Q

What type of a breeder the platypus are and when do they breed?

A
  • seasonal breeders

- July to September

25
Q

Where do the males have their testes?

A
  • inside

- Testicond

26
Q

Do platypus have spurs?

A

-yes, but only males

27
Q

Are the spurs poisonous?

A
  • yes
  • males have crural gland in their thigh connected to the spur that makes toxin
  • quite venomous= can kill a small dog and a platypus
28
Q

Who is bigger, males or females?

A
  • males much larger

- 2.7kg but females only 1.9kg the biggest one

29
Q

Does the testis weight change?

A

-yes, seasonally

30
Q

What does an annoyed male platypus do?

A
  • lock in their spurs= very rigid

- when swimming normally then more free

31
Q

When does the crural gland get more active?

A

-more testosterone and crural gland action during breeding season

32
Q

Do maple platypus home ranges overlap?

A
  • yes in non-breeding season, there is extensive overlap

- in breeding season evidence of avoidance

33
Q

Is there a male-male competition between platypus?

A
  • yes, intense

- seasonal patterns in testosterone, more fighting and venom production

34
Q

Which ovary is functional in female platypus?

A

-left only

35
Q

How long is gestation?

A

-1 month

36
Q

How many eggs do they lay?

A

1-3

  • 1-2 babies most common
  • egg is sticky and sticks to the mother and she sits on them for 10 days
37
Q

How long is incubation?

A

10 days

38
Q

Where are the young left?

A

-in the burrow

39
Q

How long does lactation last?

A

-4 months

40
Q

Can platypus breed every yearM

A

-no

41
Q

When do the young ones leave the burrow?

A
  • February

- safest to wean the babies then as not much flooding

42
Q

When is progesterone highest in females?

A
  • ovulation

- July to September

43
Q

Do platypus dig a burrow?

A
  • yes, females for young, very extensive
  • use the same one for years
  • bigger than resting burrow
  • high energy costs
44
Q

What is the seasonal change in glucocorticoids in female platypus?

A
  • breeding season = highest stress hormone

- helps with mobilising energy and flight response

45
Q

What do glucocorticoids do in mammals?

A
  • cause increased plasma concentrations of energy substrates
  • in platypus increased concentration of glucocorticoids=increased plasma free fatty acids instead of glucose
  • ability to mobilise energy in breeding season and during lactation
46
Q

Is short term stress response good?

A

-yes cannot be chronic though, then very bad for the animal

BSC Zoology - Australian Wildlife (21 decks)

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