Introduction to
Mammal Diversity
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Numbers of Species of Living Organisms
1,000,000
900,000
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
Fungi
72,000
Algae
40,000
?
Amphibians
4,200
Reptiles
6,300
Flowering Plants
270,000
Birds
9,000
Insects
950,000
Mammals
4,000
Mammal Numbers
Depending on which source you
consult:
• Total number of mammal species
currently identified is between
4,000 and 5,500
• 26 to 29 orders of mammals
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Number of Species in Mammal Orders
2500
2000
1500
1000
500
0
?
Notes on mammal evolution
• Modern mammals evolved from a group of
reptile-like animals 200 million years ago
during the Jurassic period
• When mammals arose, the earth was all
one continent, the climate was warmer,
dinosaurs were the dominant animals
• First true mammals were small, shrew-like
and nocturnal with a well-developed
sense of smell (195 million years ago)
• Following the Cretaceous-Tertiary
extinction 65 million years ago, mammals
diversified into many forms we see today
Mammal Taxonomy
•
•
•
•
Kingdom
Phylum
Subphylum
Class
•
•
•
•
Animalia
Chordata
Vertebrata
Mammalia
Monotremes Marsupials Placental Mammals
Source: “MSWIII”
Wilson, D. E., and D. M. Reeder (eds). 2005. Mammal Species of
the World. Johns Hopkins University Press, 2,142 pp. (Available
from Johns Hopkins University Press, 1-800-537-5487 or
(410) 516-6900 http://www.press.jhu.edu/.)
Three Major Groups of Mammals
Differences in embryonic development:
Monotreme: Young hatch from leathery eggs that are
similar to reptile eggs. The mammary glands have
separate openings (no nipple) and the young lap milk
from tufts of fur rather than suckling as in marsupials and
placental mammals.
Marsupial: Short gestation, no placenta in majority of
species, young born early in development, young attach
to nipple (often in pouch) to suckle and complete
development.
Placental Mammal: Longer gestation, young are
nourished prior to birth via the placenta attached to the
uterus wall. Live birth; young suckle.
Orders of Mammals
• Monotremes (5)
 Marsupials—seven
orders (331)
• Pangolins (8)
 Armadillos (21)
• Anteaters, sloths,
tamanduas (10)
• Rabbits, hares (93)
• Rodents (2,277)
• Elephant shrews
(15)
 Primates (376)
• Tree shrews (20)
• Colugos (2)
• Bats (1,116)
• Otter shrews, golden
moles, tenrecs (51)
• Hedgehogs, moonrats,
gymnures (24)
• Shrews, moles (428)
 Carnivores (287)
 Even-toed ungulates
(240)
• Whales, dolphins,
porpoises (84)
• Aardvark (1)
 Odd-toed ungulates (17)
• Hyraxes (4)
• Manatees, dugongs (5)
 Elephants (3)
Mammal Physical Characteristics
Defining characteristics:
1. Hair/fur
2. Production of milk by
modified sweat glands,
called mammary glands
3. Middle ear consists of
chain of three bones;
lower jaw is a single
bone
Mountain goat
Illustration from Occupational and Health Safety Administration
www.osha.gov
Other Physical Characteristics
of Mammals
•
•
•
•
•
•
•
•
Ectothermic (warm-blooded)
Toes end in nails, claws, or hooves
Seven vertebrae in neck
Different types of teeth: incisors, canines,
premolars, molars (number and shape
vary); teeth replaced only once
Nearly all bear live young (egg-laying
mammals are the exception)
Four-chambered heart (two ventricles,
two auricles)
Red blood cells lack nuclei (greater
capacity to carry oxygen
Larger, more complex and differentiated
brain
Mammal Reproduction
• Milk is a rich and concentrated food
source—allows for rapid growth and
maintaining body temperature
• Many mammals live in pairs during
the mating season; few mammals
form permanent pairs
Sumatran tigers
• Fertilization is internal
• Embryo derives nourishment directly
from mother (except in monotremes)
via the placenta
• Mother provides extended care to
young
Gestation
• Short in marsupials, longer in placental
mammals
• Length of gestation ranges – usually
shorter for smaller mammals and
longer for larger mammals
• Length also depends on degree of
development of newborns
• Delayed implantation results in very
long gestation (marsupials, bats,
shrews, rodents, armadillos, bears,
weasels)
Koala
Mammal Social Behavior
Different types of social groups have
evolved depending on food availability,
terrain and predators
• Solitary societies – ♀ + ♀ ♂
• Polygynous group (harem) –
♂+ ♀ ♀ ♀ ♀
• Permanent groups with complex
structure (marsupials, ungulates,
elephants, primates and some
carnivores)
– dominant pair
– matrilineal
Zebra and wildebeest
Mammal Locomotion
•
•
•
•
•
•
•
Walking/running
Jumping
Digging/burrowing
Climbing
Gliding
Flying
Swimming
Snow leopard
Hippos
Siamangs
Mammal Senses
More than half of all mammals are
nocturnal:
• all of the approx. 1,116 species of
bats
• 80% of marsupials
• 60% of carnivores
• 40% of rodents
• 20% of primates
Grey-headed fruit bats
Primary Mammal Senses
• Olfactory/Smell – chemical
stimulation of odors in the air
detected by smell membranes
in the nose
• Hearing - middle ear structure
amplifies mechanical energy
from air, which then passes
through the fluid of the cochlea
and is transferred as nerve
impulses to the brain
• Sight – more important for
diurnal mammals (full color
vision only in primates);
stereoscopic vision (both eyes
facing forward) in carnivores
and in primates
More on a few
groups of
mammals…
Monotreme Characteristics
• Egg-laying mammals
• Waste/reproductive
openings are a single
duct (cloaca)
• Lack teeth as adults
• Found only
in Australia
and
New Guinea
Duck-billed platypus
Long-beaked
echidna
Monotremes
•Five species:
–Duck-billed
platypus
–Long-beaked
echidna (3 species)
–Short-beaked
echidna
Duck-billed platypus
Long-beaked echidna
Marsupial Characteristics
• Fenestrated palate—large gaps in roof of mouth
• Brain—smaller and more simple than placental
mammals
• Teeth
–Number of incisors in upper
jaw different from number
in the lower jaw; in
placental mammals, the
number is equal
–Number of molars and premolars different in
marsupials than in
placentals
Tasmanian devil
Marsupials
• Found in North and South
America, but primarily in
Australasia (Australia, New
Guinea, nearby islands)
• Opossums (North and South
America)
• Marsupial moles, carnivorous
marsupials (Tasmanian devil,
numbats, etc.)
• Bandicoots and bilbies
• Koala, possums, gliders,
wombats, kangaroos, wallabies
Opossum
Wallaroo
Rodent Characteristics
• Found all over the world except
Antarctica, New Zealand and
some oceanic islands
• Wide diversity of diets and
habitats
• Teeth are specialized for
gnawing
– upper and lower incisors separated
from molars by a gap (no canines)
– incisors grow continuously
– enamel on front surface of incisors
but not on back = wears to a chisel
Douglas squirrel
Major Groups of
Rodents
Porcupine
• Springhaas
• Beaver, kangaroo
rats, gophers and
relatives
• Porcupines, guinea
pigs, capybaras and
relatives
• Mice, rats, gerbils
and relatives
• Squirrels and
relatives
Beaver
Bat Characteristics
• Found throughout the world, except in
polar regions
• Only mammal with true wings and
flight
• Two major ecological groups:
– Megachiroptera: eat fruit/nectar/pollen, in
Old World tropics, use vision (and thus
larger eyes)
– Microchiroptera: eat insects (or other
carnivorous diet), broadly distributed
around the world, use echolocation (and
thus larger ears)
Ungulate
Characteristics
(hoofed mammals)
• Large, barrel-shaped bodies
• Sideways-facing eyes
• Adaptations of teeth:
–reduced canines
–molars designed for crushing
plant material
• Thick skin usually covered in
hair, not fur
• Adaptations of feet:
–hooves made of keratin
–unguligrade: walk on tiptoes
–number of toes reduced to
one or three (odd-toed
ungulates) or two or four
(even-toed ungulates)
Japanese serow
in Woodland Park Zoo
Goat
Malayan
in Woodland
tapir
Park
in Woodland
Zoo
Park Zoo
Major Groups of Ungulates
• Order Even-toed Ungulates
– Pigs, peccaries, hippos
– Camels and llamas
– Ruminants (deer, giraffe, antelope,
gazelles, goats, cattle, sheep, buffalo)
• Order Whales, Dolphins, Porpoises
– New evidence that whales/ dolphins/
porpoises closely related to Even-toed
Ungulates (most closely to hippos)
• Order Odd-toed Ungulates
– Horses, tapirs, rhinos
Elephants - Physical characteristics
• Largest terrestrial animal: average height 11
ft at shoulder and average weight 5 tons
(male African savanna elephant)
• Second tallest terrestrial animal (after giraffe)
• Trunk (fused
African savanna elephant and Asian elephant
nose and
in Woodland Park Zoo
upper lip)
• Tusks (modified
upper incisors)
• Mammary glands
located between
front legs
• Large ears
What’s a Carnivore?
1. A member of the order Carnivora:
All stem from ancestors that
possessed four carnassial teeth:
sharp and bladelike upper premolars
and lower molars, used for cutting
meat and tendon
- Most modern Carnivora predators retained carnassials
- Carnassials in bears and raccoons became crushing teeth as
diets became more omnivorous
- Pinnipeds (aren’t always classified as members of the order
Carnivora) have reduced or absent carnassials
2. An animal that catches and consumes other animals
Non-Carnivora mammals, birds, reptiles, fish, etc
-
Orcas are mammals that eat a variety of aquatic prey
Raptors are birds that hunt and kill with their feet
Snakes are reptiles that use constriction or venom to kill their prey
Piranha ambush prey in rivers
General Carnivore Characteristics
• Extremely diverse group
-Smallest carnivore: least weasel at 1 to 2.5 oz (30 to 70 g)
Largest land carnivore: polar bear at 800 to 1400 lb (360 to 635
kg)
Largest aquatic carnivore: elephant seal, averages 5000 lb (2270
kg)
-Vary from mostly carnivorous diet (jaguars) to mostly herbivorous
diet (giant panda). Most will scavenge if given the opportunity.
-Some are solitary; others live in packs
• Acute senses: excellent vision, hearing and sense of smell
Carnivore Characteristics
continued
• Built for running: small, suspended collarbone allows for
long strides, fused wrist bones provide shock absorption
(and support for climbing and grappling)
- Some can run long distances, others are rapid sprinters that
use their speed to overcome their prey
• Territorial: use scentmarking to form territory boundaries
- All carnivores have special anal
glands that emit secretions, also
mark territory with urine
• Specialized reproductive
anatomy: males in all families,
except hyenas, have a penis
bone to prolong copulation
Order: Carnivora
Family members (common names)
Cats
Civets, genets
African palm civet
Mongooses
Fossa, Malagasy carnivores
Hyenas
Aardwolf
Dogs, foxes, wolves, coyote
Bears
Giant panda
Raccoons, coatis, kinkajou
Red panda
Weasels, badgers, otters, fishers, wolverines
Skunks
Eared seals, sea lions
Earless seals
Walrus
Primate
Characteristics
The following apply to
most primates:
• Opposable first digit
on hands and feet
• Social animals
• Arboreal part or all
of the time
• Color vision
• Omnivorous
DeBrazza’s guenons
Primate Characteristics
(continued)
• Forward facing eyes allows for stereoscopic
vision (ability to judge distance)
• Five digits on each limbs; usually with nails
• Longer gestation, reduced number of
offspring
• Increased complexity of brain
Drawings by Sue Cockrell
Apes
Prosimians
Primates
New World monkeys
Old World monkeys
Orders of Mammals in Washington
• Marsupials –
opossum (1)
• Rabbits, hares
(8)
• Rodents (51)
 Bats (16)
• Shrews, moles (12)
 Carnivores (25)
 Even-toed ungulates
(7)
• Whales, dolphins,
porpoises (26)
Pygmy rabbit
California sea lions
*Includes introduced species (9)
Source: Burke Museum,
http://www.washington.edu/burkemuseum/collections/mammalogy/ma
mwash/mamwash.html
Mammal Conservation
One in every four mammals faces a high
risk of extinction in the near future
(IUCN Species Survival Commission,
2004)
Factors leading to species declines:
1. Habitat destruction
2. Introduced species
3. Pollution
4. Over-exploitation
5. Global climate change
All these factors are related to human
population growth and consumption of
resources
Mammal Conservation
• Though not the largest group of
organisms, mammals represent a wide
diversity of adaptations and fill
important niches in ecosystems across
the planet
• Mammals can be “flagship species” for
conservation—people identify with and
care about cute, furry animals!
Endangered mammal photo galleries:
• http://www.iucnredlist.org/info/gallery2
006
• http://www.arkive.org/species/GES/ma
mmals/
Woodland Park Zoo—2011
Photo Credits:
Photos by Woodland Park Zoo staff:
All photos by K. Remine, M. White or J. Mears unless
otherwise noted.
All photos property of Woodland Park Zoo. All rights
reserved.
Other photos/illustrations:
All echidna photos courtesy of the Tree Kangaroo
Conservation Program
Primate characteristics illustration by Sue Cockrell
All rights reserved.
Mexican free-tail bats