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Organisms 2 > Lecture 21 > Flashcards

Lecture 21 Flashcards

1
Q

General Characteristics of Mammals (7)

A
  • Body covered with hair
  • Great variety of integumentary glands
  • Endothermic
  • Dioecious
  • Highly developed olfactory sense (smell)
  • Highly developed brain
  • Most viviparous – placental

• Notable exception: monotremes are oviparous (next lecture)

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2
Q

From Sea to Land

A

Amniotes are adapted to land

Aquatic mammals May depend partly or entirely on aquatic environment

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3
Q

Mammals

3 groups:

A 
• Monotremes: egg-laying mammals
       e.g. platypus
• Marsupials: pouched mammals
      e.g. kangaroo, koala, opossums
 • Placental mammals 
      e.g. everything else
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4
Q

Integumentary System

A
  • Integumentary system:
  • Role in protection
  • Comprised of skin and appendages
  • (e.g. hair, scales, feathers, nails, horns, antlers…)
  • Integumentary system distinguishes mammals as a group
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5
Q

Hair uses

A

• All mammals have hair, and all animals with hair are mammals

     Diverse uses for hair
 • Concealment
• Behavioral signaling
• Waterproofing
• Buoyancy
• Thermal insulation
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6
Q

two kinds of hair

A

• Underhair is soft and dense (for insulation)
• Guard hair is longer and coarse (protection
and coloration)

In aquatic mammals
• underhair is extremely dense and does not get wet
•Guard hair gets wet and forms a protective layer over the underhair

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7
Q

What is hair made of?

A
  • Dead epidermal cells containing keratin

* Keratin is a fibrous structural protein

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8
Q

What is keratin?

A

• Fibrous structural protein
• Very tough material
• Only found in chordates
• Hair, horns, nails, claws, hooves, scales (reptiles, not fish), shells,
feathers, beaks, quills
• Analagous function to chitin (produced by invertebrates)

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9
Q

What is chitin?

A
  • Nitrogenous polysaccaride
  • Very tough material
  • Found in arthropods, molluscs, annelids
    • Setae of annelids
    • Arthropod exoskeleton
    • Mollusc radula
    • Cephalopod internal shell (e.g. squid beak)
  • Fish scales
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10
Q

Shedding in mammals

A

Most mammals have two annual molts – spring and fall
• Summer coats are thinner than winter coats
• Can be different colour (e.g. white winter coat, brown summer coat)

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11
Q

Examples of modified hairs

A
  • Porcupine quills

* Vibrissae (whiskers) on the snouts of mammals

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12
Q

Horns

A
  • True horns have two parts
  • interior bone
  • sheath of keratin
  • Found in members of family Bovidae

NOT SHED NOT BRANCHED

used for social interactions, competition

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13
Q

Antlers

A
  • Composed of solid bone (no keratin)
  • Family Cervidae (moose, deer, caribou)
  • Generally, only males produce antlers
  • caribou are an exception
  • Shed
  • Grown in the spring and shed after the breeding season
  • Branched
  • Used for social interactions, competition for females
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14
Q

Glands

A
  • Great variety of integumentary glands
  • Four classes (all associated with the epidermis)
    • Sweat
    • Scent
    • Sebaceous
    • Mammary

What is a gland?
An organ or group of cells that secretes a substance that is used or excreted by the body

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15
Q

Sweat Glands

A

• Occur over much of the body surface in most mammals

Eccrine glands

  • evaporates on skin and causes cooling
  • water based
  • hairless regions in most mammals

Apocrine glands

  • milky fluid that dries and forms a film
  • Acts in thermoregulation in some mammals and as a pheromone in others
  • near puberty regions for humans (armpit breasts groin etc)
  • open into hair follicle
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16
Q

Scent glands

A
  • Occur in nearly all mammals
  • Used for
  • Communication, Marking territory, Warning, Defense
  • Most mustelids (skunks, minks, weasels) have scent glands that open by ducts to the anus
  • Most odoriferous of all glands
17
Q

Sebaceous glands

A

• Usually associated with hair follicles
• Secreted cells expel a greasy mixture called sebum into
hair follicle
• Keeps skin and hair pliable and glossy
• Most mammals have sebaceous glands covering entire body
• In humans they are mostly located on scalp and face

18
Q

Mammary glands

A
  • Produce milk for young (i.e. lactation) • Occur on all female mammals
  • Rudimentary form on male mammals
  • In most mammals, milk is secreted from mammary glands via nipples
  • Monotremes lack nipples
  • milk is secreted onto the fur of the mother’s belly where the young lap it up
19
Q

Food and Feeding for mammals

A

Mammals exploit a wide variety of food sources
• Four basic trophic categories • Insectivores
• Carnivores
• Omnivores
• Herbivores
• But many subcategories
• (these four categories don’t adequately describe all mammalian feeding habits)
Trophic = relating to nutrition

20
Q

Insectivorous Mammals

A

• Feed on insects and other small invertebrates
• Usually small
• Intestinal tract tends to be short
• eat little fibrous vegetal matter (which
requires prolonged fermentation)
• Teeth with pointed cusps for piercing exoskeleton
• Exception: Anteater - has no teeth, uses tongue

21
Q

Herbivorous Mammals

A

Feed on grasses and other vegetation
• Two main groups
• Browsers and grazers :
hooved mammals(e.g.deer, horses, cattle)
Gnawers: many rodents
• Canines are absent or reduced in size
• Molars and premolars are adapted for grinding

  • Rodents (e.g. beavers) have chisel-sharp incisors
  • Grow throughout life and must be worn away through use
22
Q

Adaptations for fibrous diet for herbivorous mammals

A

No vertebrates synthesize cellulose-splitting enzymes .:

  • anaerobic bacteria and unicellular eukaryotes produce cellulases in the gut
  • These enzymes can break down cellulose via fermentation

• Herbivores generally have long digestive tracts and need to eat
a large quantity of food to survive

23
Q

Ruminants

A

• Herbivore Mammals with a large four-chambered stomach
• E.g.cattle,goats,deer,giraffes
• Grass passes down the esophagus to
the rumen
• Digested by microorganisms in rumen
• Ruminant returns cud to its mouth, and ‘re-chews’ it
• Returns to the rumen where it undergoes a second round of fermentation
• Then carries on through “true stomach” (abomasum) where normal digestion occurs

24
Q

Carnivorous Mammals

A

Mainly feed on vertebrates, molluscs, crustaceans

• Shearing and piercing teeth, and powerful claws
• Digestive tract is shorter – meat is more easily
digested
• Feed in discrete meals
• More leisure time, but also more active
• Can survive for a long time without food

25
Q

Omnivorous Mammals

A

• Use plants and animals for food
• e.g. pigs, raccoons, many rodents, bears,
most primates
• Versatile dentition for a varied diet
• Even some carnivores often will eat fruits, berries, grasses
• Opportunistic
• categories are not always completely clear

26
Q

Territory

A
  • Many mammals have territories
  • areas from which individuals of the same species are excluded
  • Mammals mark boundaries of their territories with secretions from scent glands, and with feces or urine
  • Territories vary greatly in size depending on size of animal and its feeding habits
  • Advantages of a territory
  • Interruption-free mating
  • Reduce competition for food (particularly when raising young)
  • Reduce overcrowding
27
Q

Three Main Branches of living mammals

A

• Subclass: Prototheria (Monotremes) • Oviparous mammals
Duck-billed platypus and echidna (that’s it!)

• Subclass: Metatheria (Marsupials)
American opossums Koala, wombats, possums, wallabies and kangaroos

• Infraclass: Eutheria (Placental Mammals)
Many groups!

Organisms 2 (23 decks)

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