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

Virginia opossum …

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 …