phylum chordata subphylum vertebrata a survey of diversity bio 122: zoology part 3 mammals
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PHYLUM CHORDATASUBPHYLUM VERTEBRATAA SURVEY OF DIVERSITY
BIO 122: ZoologyPart 3
Mammals
CLASS MAMMALIA
Mammals Dermal covering of hair on most internal fertilization & development 4-chambered heart
CLASS MAMMALIA
Additional characteristics: integument with sweat, scent & mammary
glands diphyodont teeth (milk & permanent) movable eyelids & fleshy ears endothermic (heat from own metabolism) homeothermic
(maintain body temperature = warm blooded)
CLASS MAMMALIA
Dermal coverings (all have a hair or it's derivative):
Pelage (fur)a) dense & short hair - for insulation (can be shed)b) coarse longer hair - for protection & coloration
Vibrissae (whiskers) - sensory hairs Nails, claws & hooves - very dense on
appendage tips
CLASS MAMMALIA
Variation of appendages: tetrapods terrestrial - 4 legs aquatic with modified to fins bats with webbings on front appendages –
wings 2 legs & 2 arms - can walk erect
CLASS MAMMALIA
Reproductive patterns: 3 Infraclasses Monotremes
duck-billed platypus & echidnaegg-laying, hatch early & feed off mothers milk
Marsupials kangaroo, opossumshort development in uterus, birth, long lactation
Placentals cat, dog, humanlong development in uterus, birth, short lactation
INFRACLASS ORNITHODELPHIA
Monotremes – egg-laying mammals embryos develop for 10-12 day in uterus leathery shell is secretes around embryo eggs hatch in 10-14 days young obtain milk from mother, but no
nipples are presentInclude:
duck-billed platypus, echidnas (spiny anteater)
INFRACLASS ORNITHODELPHIA
Duck-billed platypus (l), Echidna (r)
INFRACLASS METATHERIAINFRACLASS METATHERIA
Marsupials – pouched mammals the developing embryos do not implant in
the uterus cause development of shallow depressions
in uterine wall absorb nutrients through a vascularized
yolk sac gestation (time in uterus) is short followed by a prolonged
development in a sac where they lactate for a long time
INFRACLASS METATHERIAINFRACLASS METATHERIA
Marsupials: Numerous animals in this group, including four orders.
opossums (80+ species) – Americas marsupial mice – Australia & Tasmania bandicoots – Australia & Tasmania koalas, wallabies, kangaroos –
Australia to East Indies
Tasmanian devil (l) & numbat (r)
Bandicoot …
Koala …
Sugar glider …
Wallaby (l) & Kangaroo (r)
Wallaby is smaller
Red Kangaroo …
INFRACLASS EUTHERIA
Placentals - viviparous mammals embryos do implant in uterus for a
prolonged period a placenta develops for embryo
attachment in the uterus gestation time varies (from 21 days in
rabbits to 22 months in elephants)
INFRACLASS EUTHERIA
The Placentals have been divided into a number of Orders based on:
1. Skull and snout shape2. Dental formula
(incisors, canines, premolars and molars)3. Limbs (size & shape)4. Number digits on appendages5. Claws, nails on appendages
ORDERS OF PLACENTALS
Shrews and moles small body elongate snout limbs pentadactyl teeth primitive (not very complex)
Shrews and moles …
Shrews – long tail, visible ears, small feet Moles – short tail, obscure ears, large front
feet
ORDERS OF PLACENTALS
Bats Wings with limb bones greatly elongated claws on only first two digits of front limbs hind legs pentadactyl use of echolocation
Bats …
Evening bat
Bats …
Rafinesque’s Bat (l) Eastern Red Bat (r)
ORDERS OF PLACENTALS
Primates (lemurs, monkeys & humans) enlarged cerebral hemispheres limbs with ball & socket articulation pentadactyl digits
(opposable thumb)
Primates …
Spider monkey
ORDERS OF PLACENTALS
Edentates (anteaters, armadillos & sloths) At least some front claws enlarged
(for digging or hanging) teeth reduced (peg-like)
or absent
Nine-banded armadillo
Yes, road kill
Three-toed sloth …
ORDERS OF PLACENTALS
Rabbits & hares tail short or vestigial ears medium to large 4 upper incisors
(front teeth for biting)
Rabbits …
Cottontail (l) & swamp rabbit (r) - notice ear size
ORDERS OF PLACENTALS
Rodents (mice, rats, beavers, squirrels) 2 upper incisors which permanently grow canine teeth missing
Mice and rats …
Beaver …
Squirrels …
ORDERS OF PLACENTALS
Carnivores (dogs, wolves, fox, bears, raccoons)
at least four clawed toes on each foot incisors small, canines large
Gray wolf …
Red fox …
Brown bear …
Cheetah …
Tigers …
Raccoon …
ORDERS OF PLACENTALS
Elephants long trunk (proboscis) ears very large long incisors (tusks)
ORDERS OF PLACENTALS
Perissodactyls (horses, zebras, rhinoceros) foot ending on third digit (hooves) odd-toed mammals head elongate ears moderate & tubular
Horses …
Burchell’s (Plains) Zebra …
Rhinoceros …
ORDERS OF PLACENTALS
Artiodacytls (cows, goats, deer, hippos) Hooves (commonly 2) even-toed mammals upper incisors reduced
Cows & goats …
Whitetail deer …
Hippopotamus …
26-JUN-2005
Joey Cha
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ORDERS OF PLACENTALS
Dolphins, porpoises & whales aquatic with fins (hind appendages
lacking) skin essentially lacking hair external ears lacking blowhole
Dolphin …
Porpoises lack distinct beak
Humpback whale …
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