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Diversity of Life 2 > Mammals > Flashcards

Mammals Flashcards

1
Q

What are the two most unique features of mammals?

A

Produce milk for young.

Hair.

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2
Q

What skull fenestration do mammals have?

A

Synapsid.

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3
Q

What were the line of animals which led to mammals?

A

Pelycosaurs -> Therapsids -> Therians -> Mammals.

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4
Q

When did mammals emerge?

A

Triassic.

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5
Q

What were the first mammals like?

A

Nocturnal.
Endothermic.
Acute hearing and smell.
Small and insectivores.

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6
Q

What are the three major clades of mammals?

A

Marsupials.
Eutherians.
Monotremes.

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7
Q

Give general mammalian characteristics.

A 
Hair
Distinctive teeth.
Sweat glands. 
Mammary glands.
4-chambered heart.
Extended care for young.
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8
Q

What is mammal reproduction like?

A

Internal fertilisation.

Viviparous apart from monotremes.

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9
Q

What is monotreme reproduction like?

A

1 or 2 eggs laid.
Eggs fertilised in fallopian tube.
Receive a mucoid membrane which allows them to expand by 3x in the uterus, nourished by maternal secretions.
Mineralised shell is then applied and eggs are laid and incubated.
Very immature young.

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10
Q

What is the function of the allantois?

A

Extra-embryonic membrane responsible for gas exchange, blood formation and waste removal.

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11
Q

What is the function of the amnion?

A

Membrane responsible for fluid exchange.

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12
Q

What is the function of the chorion?

A

Outermost membrane, involved in gas exchange.

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13
Q

What is marsupial reproduction like?

A

Yolk-sac placenta.
Eggs fertilised in fallopian tube.
Females have two vaginas, while a third birth canal forms between them for birth.
Embryo is nourished by yolk sac in uterus, supplemented by maternal secretions.
Placenta does not attach to maternal tissues.
Have allantois, amnion, avascular and vascular yolk sac.
On male, testicles on top of penis. Many species have a divided penis.
Young’s jaws, secondary palate, facial muscles and tongue advanced for easy attachment to nipple.
In kangaroos, mother licks path from vagina to pouch and joey climbs into it.
First milk is protein-rich and later milk is fat-rich.

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14
Q

What is eutherian reproduction like?

A

Well-developed placenta, a temporary organ made of maternal and foetal tissues.
Foetus attaches to placenta with umbilical cord.
Urinary tract can be fused or separate from genital tract.
Uteruses may be separate or fused.
Have chorion, amnion, allantois and yolk sac.
Chorionic villi is the foetal portion of the placenta.

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15
Q

What does the placenta do?

A
  • Anchors foetus to uterus.
  • Transports nutrients to foetus from mother.
  • Excretes metabolites to maternal circulation.
  • Produces hormones to regulate mother and foetal organs.
  • Suppresses maternal immune response.
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16
Q

What are some adaptations to ensure optimal birth time in mammals?

A
  • Delayed fertilisation.
  • Delayed development.
  • Delayed implantation / embryonic diapause.
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17
Q

What is social reproductive suppression?

A
  • Behavioural.
  • Stress-induced.
  • Pheromonal.
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18
Q

What is diphyodonty?

A

The full replacement of one set of teeth with another set, this indicates lactation. Most mammals are diphyodonts.

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19
Q

What is polyphyodonty?

A

Multiple replacements of teeth. Most vertebrates are polyphyodonts.

20
Q

How do mammals eat?

A

Mammals have four different types of teeth:
Incisors for seizing food.
Canines for stabbing food, tusks are modified canines.
Premolars for piercing and slicing food.
Molars for breaking food into fine pieces.
Jaws move in a rotary fashion.

21
Q

What are herbivore teeth like?

A

Use entire post-canine tooth row for mastication.

22
Q

What are carnivore teeth like?

A

Canines used to stab and specialised post-canine teeth as shears.

23
Q

What are omnivore teeth like?

A

Premolars and molars rounded, flattened, suitable for crushing.

24
Q

What are insectivore teeth like?

A

Triangular shape for puncturing cuticles.

25
Q

What are anteater teeth like?

A

Reduced teeth, instead a long tongue and large salivary glands.

26
Q

Where are digestive enzymes in mammals?

A

In saliva as starch and fat.
In the stomach as proteins.
In small intestine as starch fats and proteins.

27
Q

How have cows adapted to digest cellulases?

A

They have pre-stomach chambers:
Rumen - processes plant material mechanically, exposed to bacteria to break down cellulose.
Reticulum - passes mixture back to mouth.
Osmasum - further mechanical processes.
Abomasum - bacteria lysed and nutrients released.

This allows fermentation of starch, cellulose and proteins.

28
Q

Describe saltatorial locomotion.

A

This is bipedal hopping.
Animals which move like this have very long hind limbs and large hind limb muscles.
Reduced number of hind limb digits. Spine stiffened and long counter-balancing tail.
Cervical vertebrae fused.
Ligament shock absorbers.
Extremely rapid acceleration and rapid changes in direction.

29
Q

Describe cursorial locomotion.

A

This is running.
Can increase speed with stride rate or stride length.
To increase stride length:
- Elongated distal limb bones.
- Change foot posture to reduce contact with ground.
- Reduced clavicle allowing scapula to pivot and rotate as part of limb.
- Increase dorso-ventral flexion of spine.
To increase stride rate:
- Increase number of joints. Decrease inertia of limb distally.
- Concentration of muscles to proximal locations.

30
Q

Describe scansorial locomotion.

A 
This is climbing.
Large climbers seem to be more careful when compared to small ones. 
Friction pads on hands, feet and digits.
Claws for digging into substrate.
Prehensile tail and opposable digits.
Suction cups.
Stiffened trunks for vertical support.
Elongated forelimbs.
31
Q

Describe gliding locomotion.

A

Skin webbing between limbs.
Reduced drag.
Tail/rudder/balance.
Help control fall.

32
Q

Describe the difference between semi-aquatic and aquatic animals.

A

Semi-aquatic animals have long bodies and limbs with some webbing. Aquatic animals have flippers for thrust and propulsion and fused cervical vertebrae.

33
Q

Describe digging locomotion.

A

Limbs for power over speed.
Rodents use incisors to dig.
Moles dig by rotating forelimbs to earth instead of retracting them.

34
Q

What does plantigrade mean?

A

Foot flat on ground. e.g. human.

35
Q

What does digitigrade mean?

A

Walk on toes. e.g. cat.

36
Q

What does unguligrade mean?

A

Walk on tiptoes e.g. horses.

37
Q

How is temperature monitored in mammals?

A

Receptors in hypothalamus monitor core blood temperature when it passes through the brain.
Skin receptors monitor external temperature.

38
Q

What mechanisms are in the heat-conversion centre?

A

Vasoconstriction.
Shivering.
Hair-raising.
Increased metabolism.

39
Q

What mechanisms are in the heat-loss centre?

A

Vasodilation.
Sweating.
Hair-lowering.
Decreased metabolism.

40
Q

What is blubber?

A

A complex tissue that consists of collagen and adipocytes. Plays an important role in lactation and buoyancy as well as thermoregulation.

41
Q

Name behavioural ways of controlling body temperature.

A 
Basking.
Ball-like posture.
Nesting.
Huddling.
Piloerection.
Maximise exposure of skin.
Sweating.
Anti-piloerection.
Panting.
Activity levels.
42
Q

What is brown fat and what does it have to do with mammalian thermoregulation?

A

A highly specialised tissue with a high metabolic capacity. Brown due to high mitochondrial density. Derived from skeletal muscle.

43
Q

What does fever do to us?

A 
Increased phagocytic activity.
Increased antibody production.
Decreased virus replication.
Increased metabolism.
Decreased blood pressure.
Reduced activity.
Reduced social contact.
44
Q

What is adaptive hypothermia?

A 
Decreased heart rate.
Vasoconstriction.
Decreased breathing rate.
Suppression of shivering.
Decreased oxygen consumption.
Decreased body temperature.
45
Q

What is deep adaptive hypothermia also known as?

A

Hibernation.

46
Q

What is shallow adaptive hypothermia also known as?

A

Torpor.

47
Q

How much of the mammal population is at risk of dying out due to environmental changes?

A

1/3.

Diversity of Life 2 (16 decks)

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