Chapter 2: Mammalian Characteristics Flashcards
(101 cards)
1
Q
Why are mammalian characteristics important to species?
A
- Promote endothermy
- Increase efficiency of reproduction/securing food
- Increase intelligence and sensory ability
- Extended parental care for demanding foraging patterns & complex social behaviours
2
Q
What is a endotherm?
A
An organism that maintains its body temperature, largely by heat released from internal bodily functions
3
Q
What is ectoderm?
A
An organism that primarily on its ambient environment to regulate body temperature
4
Q
What reptilian group were mammals from?
A
Therapsida - an order of Synapsid
5
Q
How did Therapsids dominate and allow their descendants to survive through the Triassic, Jurassic and Cretaceous periods?
A
- Perhaps through their ability to move and think more quickly
- They also had highly specialised dentition, which could utilise certain foods more efficiently than other reptiles
6
Q
What are the changes to the Theraspid skeleton through evolution?
A
Simplification - thus advanced therapsid skeleton resembles monotremes, though some were less laterally splayed than those today
- Skull & lower jawbones were reduced in number compared to primitive reptiles
- simplified limbs & limb girdle
- reduce massiveness
7
Q
What is the order of monotremes?
A
Monotremata
8
Q
What paleontologic evidence showed that animals had crossed the mammalian-reptilian boundaries?
A
The dentary/squamosal jaw articulation
9
Q
According to Else & Hulbert, how are the capacity for energy production and standard metabolic rate differ in reptiles and mammals?
A
Mammals have a 3-6 hold greater capacity for energy production than reptiles, and a standard metabolic rate some 8 times higher
10
Q
What is a gland that is only found in mammals?
A
mammary gland
11
Q
What is the purpose of mammary glands?
A
provide nourishment for young during postnatal period of rapid growth
12
Q
What is the prominent part on the surface of the skin of the mammary glands?
A
teat/nipple
13
Q
What do oestrogen and progesterone stimulate during pregnancy?
A
Oestrogen = stimulate lactiferous ducts Progesterone = formation of milk glands
14
Q
What does prolactin do during pregnancy?
A
stimulate milk production
15
Q
How does lactation positive feedback happen?
A
Baby suckles - stimulates all nerves on the areola to release prolactin (milk secretion) and oxytocin (muscle contraction)
16
Q
What does cow milk contain?
A
85% water
remaining dry weight: 20% protein, 20% fat, 60% sugars (largely lactose), vitamins & salts
17
Q
How much more fats and proteins do seal’s milk contain compared to cows?
A
12x more fat & 5x more proteins
18
Q
Why are lactation and suckling important in many mammals?
A
Strengthen mother-young social bonds
Training for future complex social behaviour patterns & complex foraging
19
Q
How does suckling differ in monotremes?
A
Lack teat/nipples - instead young sucks from a tuft of hair on mammary areas
20
Q
How are whales, dolphins, and porpoises adapted for nursing?
A
contain muscles that force milk into mouths of the young (lack lips for sucking)
21
Q
How many nipples do mouse opossums have?
A
19
22
Q
Where do the eccrine glands of some insectivores, rodents, and carnivores locate?
A
on the feet/venter
23
Q
What is the body temperature of adult chickens?
A
between 40.6°C and 41.7°C.
24
Q
How do chickens regulate body temperature?
A
Panting & evaporative cooling from the surface of their lungs and air sacs
25
What are scent glands and musk glands for?
marking territories, communication, protection
26
How to spot a musk gland?
marked by a dark hair patch on animals
27
What is skin made of?
Keratin
28
What are the 3 morphological regions in hair?
1. Cuticle = outer layer with a scale-like pattern
2. Cortex = middle layer highly packed with cells
3. Medulla = central core with cuboidal cells
29
What is a cuticle?
Translucent outer layer of the hair shaft consists of scales that cover the shaft
Cuticular scales always point from the proximal/root to the distal/tip end
30
What are the 3 basic scale patterns that make up the cuticle?
1. Coronal (eg Bat hair)
2. Spinous (eg Mink)
3. Imbricate (eg Human)
31
What is a medulla?
A central core of soft, thin core of transparent cells and air spaces
32
What is the general difference between human and animal hair medulla?
Human hairs - generally amorphous in appearance
| Animal hairs - very regular and well defined
33
What are the 3 types of medulla?
1. Fragmentary/trace
2. Discontinuous/broken
3. Continuous
34
What is a cortex?
Composed of elongated and fusiform (spindle-shaped) cells - also contain cortical fusi, pigment granules, and/or large ovoid bodies
35
What are hair pigment granules?
Small, dark, solid structures that are granular in appearance and smaller than cortical fusi - vary in colour, size, and distribution in a single hair
36
Where are pigment granules distributed in humans and animals?
Humans - pigment granules are commonly distributed toward the cuticle (except in red-haired individuals)
Animal - pigment granules are commonly distributed toward the medulla
37
What is the function of pelage?
Insulation
NB: dissipation and absorption of heat from the environment are retarded by pelage
38
What do animals that live in extremely cold water have for insulation?
Hair and cutaneous bubbler
39
Why do elephants, hippopotami, and rhinoceroses have sparse hair?
They live in warm areas
| Have thick skin and a large surface-area-to-volume ratio that retains body heat
40
What happens during periodic moulting in animals?
Old hairs are lost and are replaced by new ones
NB: Summer pelage is usually shorter & less insulating than winter pelage
NB: In continuous snow-cover areas, summer pelage is brown and winter pelage is white
41
How does habitat affect the colouration of animals?
Nocturnal, dark substrates (eg dark forest soils) = dark coloured
Diurnal, light substrates (Eg light soils) = light coloured
42
Why are animals universally darker at the back & sides and lighter on the underside?
The form of the animal becomes obscured to some extent and the animal becomes less conspicuous
43
What is an ungulate?
A hoofed animal
44
How do some facial markings in mammals obviate bold pattern of the eye?
By superimposing a more dominant and disruptive pattern
45
How do some facial markings in mammals such as viscacha & tent-building bats help with survival?
Obviate bold patterns of the eye by superimposing a more dominant and disruptive pattern
Allow animals to go unnoticed/cause predators to be indecisive with their attack
46
What do zebra patterns do?
Create optical illusion and increase the apparent size of zebras
47
What is the scientific name of the Plain viscacha?
Lagostomus maximus
48
What family does viscacha belong to?
Chinchillidae
49
What is the scientific name of tent-building bats?
Uroderma bilobatum
50
What family does Uroderma bilobatum belong to?
Phyllstomidae
51
What is the scientific name for pronghorn antelope?
Antilocapra americana
52
What family does Antilocapra americana belong to?
Antilocapridae
53
What are the functions fat serves?
1. energy storage
2. source of heat and water
3. thermal insulation
54
Where do desert dwellers and mammals of temperate areas store their fat?
localised fat storage in the tail/inguinal/abdominal areas
55
Where do aquatic mammals store their fat?
subcutaneous layer
56
What circulatory system has mammals adapted to?
double circulatory system
57
What is the range of heart rate for non-hibernating mammals?
Under 20 hr/min in seals to over 1300 hr/min in shrews
58
What are Microchiroptera and Megachiropetra?
microbats and megabats
59
What are the 3 families in Microchiroptera?
Phyllostomidae (new world leaf-nosed bat), Vespertilionidae (evening bat), and Mormoopidae (moustached bat)
60
Give an example of a Vespertilionidae.
Eptesicus fuscus
61
How does a big brown bat alter their heart rates rapidly?
Originally 400 hr/min; increase to about 1000 when it takes flight within 1 s & returns to normal after flight
62
What are the shapes of erythrocytes in mammals and why?
Biconcave disks - increase O2 carrying capacity
63
What is Artiodactyla?
Even-toed ungulate
64
What are the different types of uteri (stippled) found in placental mammals?
1. Duplex uterus
2. Bipartite uterus
3. Bicornuate uterus
4. Simplex uterus
65
What species contain a simplex uterus?
Primates, Chiroptera, and the order Edentata
66
What is the family of Edentata?
Xenarthra
67
What are animals related to Xenarthra?
31 living species including anteaters, tree sloths, and armadillos
Extinct xenarthrans include glyptodonts, pampatheres aquatic sloth, and ground sloths
68
What species contain a bicornuate uterus?
Order Insectivora, some members of Chiroptera & primates, orders of Pholidota, Carnivora, Proboscidea, Sirenia, Perissodactyla, Artiodactyla
69
What's the difference between pangolins and armadillos?
Armadillos: tough carapace all over the body & long sharp claws for digging
Pangolins: distinctive external armour of overlapping epidermal scales (only mammals with such armour that grows from their thick underlying skin)
70
What animals belong to the order Pholidota?
Pangolins (scaly anteaters)
71
What is the order of armadillos?
Cingulata
72
What is the order of pangolins?
Pholidota
73
What does eutherian mean?
Major division of mammals comprising placental mammals
74
What is Carnivora?
eutherian animals that have teeth adapted for flesh eating
75
What is the order of Proboscidea?
Order of afrotherian mammals containing Elephantidae and several extinct families
76
What is the order of Sirenia?
Sea-cows; an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters
77
What are the 2 distinct families of Sirenia?
1. Dugongidae (the dugong and the now extinct Steller's sea cow)
2. Trichechidae (manatees, namely the Amazonian manatee, West Indian manatee, and West African manatee)
78
What is the order of odd-toed ungulates?
Perissodactyla
79
What are the 3 families within Perissodactyla?
About 17 species
1. Equidae (horses, asses, and zebras)
2 Rhinocerotidae (rhinoceroses)
3. Tapiridae (tapirs)
80
What is the difference between weight-bearing toes of odd-toed & even-toed ungulates?
Perissodactyla reduced their weight-bearing toes to 3 (rhinoceroses and tapirs) or even 1 (horses, 3rd toe) of the 5 original toes - non-weight-bearing toes are either present/absent/vestigial/positioned posteriorly
Artiodactyla bear most of their weight equally on 2 of the 5 toes (3rd &4th)
81
What is the difference in cellulose digestion between Perissodactyla and Artiodactyla?
odd-toed ungulates digest plant cellulose in their intestines
even-toed ungulates digest through one/more stomach chambers (except Suina)
82
What is the suborder Suina?
Omnivorous, non-ruminant artiodactyl mammals that include the pigs and peccaries.
Includes family Suidae (pigs/swine) & Tayassuidae (tayassuids/peccaries)
83
What mammals have a bipartite uterus?
Order of Cetacea
84
What is the order of Cetacea?
Any member of an entirely aquatic group of mammals commonly known as whales, dolphins, and porpoises
85
What order are Cetacea originated from?
Artiodactyla
86
What is the current order of Cetacea?
Cetartiodactyla
87
What is the closest relative to Cetacea?
Hippopotamus
88
What animals have a duplex uterus?
Orders Lagomorpha, Rodentia, Tubulidentata, and Hydrocoidea
89
What is the order of Lagomorpha?
Contains 2 living families of Leporidae (hares and rabbits) and Ochotonidae (pikas)
109 extant species including 34 pikas, 42 rabbits, and 33 hare
90
What is the order of Rodentia?
Characterized by a single pair of continuously growing incisors in each of the upper and lower jaws (~40% mammals are rodents)
91
What are the structures of a rodent tooth system?
The front surface of the incisors is hard enamel, whereas the rear is softer dentine
Incisors never stop growing, so must continue to wear them down to prevent piercing of the skull
Contains a diastema between incisors & molars
92
What is the order of Tubulidentata?
Belongs to the family Orycteropodidae#
| The only surviving species is Aardvark (Orycteropus afer)
93
What is the order of Hyracoidea?
Dassies: small, thickset, herbivorous mammals
Hyraxes are well-furred, rotund animals with short tails; superficially similar to pikas and marmots, but are more closely related to elephants and sea cows.
94
What are the 5 extant species of hyraxes?
1. Rock hyrax (Procavia capensis)
2. Yellow-spotted rock hyrax (Heterohyrax brucei)
3. Western tree hyrax (Dendrohyrax dorsalis)
4. Southern tree hyrax (D. arboreus)
5. Eastern tree hyrax (D. validus)
95
What tissues does the male copulatory organ contain?
erectile tissues and surrounded by a sheath of skin (prepuce)
96
What is the bone within a penis called?
os penis/baculum
97
What is a celomic cavity?
A hollow-body cavity containing a fluid-filled cavity that envelopes internal organs
98
Where are testes stored in other vertebrates?
celomic cavity
99
Where are testes stored in eutherians?
scrotum
100
How is the overall size of mammal brains compared to other vertebrates?
larger due to enlarged cerebral hemispheres
101
What structure is greatly developed in higher mammals for most of their characteristics?
Neopallium
