Mammals_and_Zoo_BI_2 Flashcards
(131 cards)
1
Q
Q: Where do mammals fall in the taxonomy of organisms? How are mammals classified?
A
Mammalia is one of the five (actually >5 because multiple fish classes) classes in the Vertebrata subphylum.
Kingdom: Animalia; Phylum: Chordata; Subphylum: Vertebrata; Class: Mammalia.
There are three divergent lines (subdivisions) of mammals based on their reproductive strategy: the monotremes (which is its own order), marsupials (infraclass w/multiple orders), and placental mammals (infraclass w/multiple orders).
2
Q
Q: Five classes of vertebrates
A
Fish (actually multiple fish classes), amphibians, reptiles, birds, and mammals.
3
Q
Q: Mammal characteristics (and name some benefits of the characteristics)
A
-Endothermic, generate their own heat. By generating their own heat mammals are free from depending on the ambient temperature of their surroundings for warmth.
-Have hair at some point during their life cycle. Hair is unique to mammals. Provides insulation, concealment, signals to others, defensive functions, and a sense of the surroundings.
-Give birth to live young (except monotremes).
-Breathe air with lungs. Aquatic mammals come to the surface to breathe and replenish their oxygen.
-Dermal glands which include mammary glands in females. Mammary glands produce milk to feed their young until they can eat normal food. Thus, female mammals invest a great deal of energy caring for their offspring, which increases survival rate.
-Relatively larger brain to body size than reptiles and has many folds or convolutions; allows increased degree of muscle coordination, enabled stronger sense of smell, higher intelligence, better memory development, more complex emotions, capacity for emotional bonds.
4
Q
Q: Mnemonic for mammal characteristics
A
WHALE: Warm blooded, Hair or fur, Air to breathe, Live birth, Eats mom’s milk.
5
Q
Q: Describe early mammals; when did mammals emerge?
A
-Mammal ancestors were mammal-like reptiles that were around about the same time as the emergence of dinosaurs.
Early mammals:
-The earliest identifiable mammals were tiny, shrew-like mammals.
-Emerged during the late Triassic period about 200 million years ago.
-Probably nocturnal in order to avoid competition with the dominant carnivorous dinosaurs.
-Probably mostly ate insects and lived in the trees.
-Probably laid eggs.
-Superior sense of smell and hearing, backed up by a larger brain, facilitated entry into nocturnal niches with less exposure to dinosaur predation. The nocturnal lifestyle may have contributed greatly to the development of mammalian traits such as being endothermic and having hair.
6
Q
Q: Describe the important factors/events involved in the expansion of mammals
A
-After the extinction of the Dinosaurs, about 65.5 mya, the Cenozoic became the “Age of Mammals”
-Flowering plants and mammals underwent rapid diversification at this time and filled in open niches that were left vacant by the dinosaurs and marine reptiles
-Mammals took advantage of the new abundant food sources from the evolving flowering plants.
-Part of the successful strategy was the differentiated teeth (incisors, canines, molars), allowing them to adapt to a variety of diets and environments. (Fish, amphibians and reptiles, which all evolved prior to the mammals, had a single tooth morphology.)
7
Q
Q: One downside of being endothermic? What does that mean for Mammals?
A
Requires more calories. The caloric need of an endotherm is 4–5 times more than a similar size ectotherm.
Mammals spend the majority of their time in search of food.
An area of the brain (neocortex) probably evolved as a part of a set of adaptations related to temperature homeostasis; this area stores information about the structure of the environment so that the mammal can readily find food and other resources necessary for its survival.
8
Q
Q: Benefit of extended periods of parental care in mammals?
A
Improves survival rate of offspring. (vs. e.g., reptiles, amphibians, arthropods)
9
Q
Q: What is the oldest living group of mammals?
A
Monotremes (order: Monotremata)
10
Q
Q: Mammal fertilization
A
All three types of mammalian reproduction involve internal fertilization.
11
Q
Q: Benefit of nursing in primates unrelated to nutrition/consumption?
A
Helps in social bonding.
12
Q
Q: Mammal physical adaptations to maintain high body temperature in cooler climates
A
Dense fur and blubber
13
Q
Q: Mammal methods for maintaining optimal body temperatures (behaviors/actions/body changes, not relatively static physical structures like blubber)
A
Constriction or dilation of blood vessels, shivering or sweating, piloerection of the fur, panting, and behavioral changes such as body postures, licking the fur, huddling together.
Countercurrent heat exchange (details on separate card in bird section)
14
Q
Q: Homeothermic vs endothermic
A
Endothermic: capable of the internal generation of heat through metabolic means
Homeothermic: maintains a constant body temperature
Note: there are homeotherms that are not endothermic.
Mammals are both endothermic and homeothermic. Allows them to inhabit regions with extreme temps.
15
Q
Q: Differences between individuals of the same species that are found in cooler vs. warmer climates?
A
Individuals from cooler climates tend to be larger than individuals of the same species living in warmer climates.
Appendages, such as limbs, nose, tail and ears, tend to be shorter in the cooler climates as well.
Larger mammals have less heat loss than smaller mammals due to the fact that heat loss is proportional to surface area.
16
Q
Q: Mammal adaptations to hot/dry environments
A
-Changes in insulation, metabolic rate, and body size.
-Small mammals avoid extreme heat by adhering to definite periods of activity, and/or by occupying burrows during the heat of the day.
-Desert mammals produce dry feces to conserve water.
-Lighter fur reflects direct sunlight.
-Fur is also an excellent insulation against heat.
-Evaporative cooling from external body parts, e.g., Kangaroos lick their paws.
-Evaporative cooling from the respiratory tract is a major avenue of water loss but is also an important device for cooling.
-Larger animals save water by allowing their body temperatures to rise before it is necessary to pant to cool off thus reducing water loss. E.g., scimitar-horned oryx.
-The scimitar-horned oryx has specialized kidneys that prevent excess loss of water by producing very concentrated urine. Able to live in the desert without water for extended periods of time.
17
Q
Q: The most important characteristic in mammal identification?
A
Its teeth.
18
Q
Q: What is a secondary palate? Benefits?
A
Anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates.
Allows mammals to breathe while nursing or chewing food.
Provides a surface on which the tongue can manipulate food, facilitating chewing.
19
Q
Q: Describe mammal teeth (generally; specifics are a separate question)
A
All mammals have teeth except for monotremes, anteaters, and certain whales.
Mammals are heterodonts (means having multiple kinds of teeth; unlike homodonts like reptiles and fish).
Different kinds of teeth perform different functions such as chewing, crushing, cracking, gnawing, grooming, digging, defending and communicating.
The kind of teeth (shape, size and number) reflect their diet and lifestyle.
In mammals, teeth in upper jaw match up with lower jaw, which aids chewing, esp. in helping to break down plant material. (Reptile teeth do not match up, many species swallow food whole.)
20
Q
Q: Heterodont
A
Animal having different kinds of teeth; for example, most mammal teeth are differentiated into incisors, canines and molars.
21
Q
Q: Name one key way to differentiate mammal species
A
Comparing teeth shape and quantity
22
Q
Q: Which kinds of teeth do most mammals have? Describe their location and function.
A
Incisors: in the front (anterior) of the mouth and used for food gathering. They are designed for biting, cutting, gnawing, stripping.
Canines: positioned at the front of the mouth between incisors and first molars. They are sharp for piercing and are designed for grabbing, piercing, and tearing. Predators use their canines to kill their prey.
Molars and premolars (also known as cheek teeth): in the sides/back of the mouth, vary in shape or size depending on their function. Premolars are used for grinding, crushing, slicing, and shearing, whereas molars are designed to grind and crush vegetation.
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Q
Q: How does a skull reveal information about animal feeding behavior?
A
Skulls provide a framework for the muscles an animal needs for chewing and biting.
In this way, the shape of the skull reveals information about the chewing and biting behavior.
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Q
Q: Describe some specific aspects of a skull that reveal information about animal jaw function, distinguishing predator/prey
A
Skulls provide attachment sites for muscles that enable biting and chewing.
Animals that need stronger biting muscles will develop larger bony attachment ridges for these muscles, such as the sagittal crest along the top of the skull and the zygomatic arches (cheek bones) on the sides.
Predators that tackle large prey often develop a sagittal crest, since it provides attachment space for muscle, which is used to snap the jaws shut (e.g., dog/wolf).
Sagittal crests are often larger in males than in females, because they are associated with larger body size.
Herbivorous animals that do a lot of chewing to help break down the cellulose, have a larger muscle attachment sight on the lower jawbone (e.g., cow). If this attachment area is small, chewing is not a necessity such as in a cat or dog.
25
Q: Which animals have hair/fur?
Mammals are the only animals that have hair or fur, and all mammals have it. It's one of their defining characteristics.
26
Q: What is a pelt?
A mammal's skin and fur.
27
Q: Name some functions of mammal skin
Primary function is defense against injury.
Barrier to protect the animal's soft inner structures and maintain the internal environment by retaining body fluids.
Prevent moisture loss.
Keep germs out.
The skin may be extremely tough and durable.
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Q: Types/functions of fur:
The fur (pelage) is made up of two layers of hair:
-1. dense and soft undercoat/underfur - traps a layer of air, providing insulation (thermoregulation is most important function of hair)
-2. long, coarse hairs form outer coat - protection against wear, can be fluffed up to improve insulation or as defensive/aggressive behavior to make mammal appear larger, provides coloration
Other functions:
-May also provide insulation against heat (camel, kangaroo or lion). Paler fur reflects the sun's rays.
-Coloration for camouflage, signals/communication (warnings, mating display)
--Sometimes this coloring is disruptive by patterns of stripes or colors that stand out from the basic background fur color. These patterns allow the animal to blend in with the background mixture of sunlight and vegetation. Body shapes and outlines are not as readily distinguished when animals have disruptive coloration patterns.
-Sensory function: nerve endings are wrapped around the follicle and are sensitive to a hair's movement. Mammals use this sense to detect direct physical contact and to gauge wind or water currents.
-Rarely: offensive protection
29
Q: Pelage
Fur or pelt
30
Q: What is hair/fur made of?
Hair/fur is dead and made of keratin.
31
Q: Example animal structures made of keratin
hair/fur
whiskers
beaks
horns and/or horn sheath
scales
plates
feathers
fingernails/claws
hooves
baleen in whales
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Q: Are antlers made of keratin?
No. Bone.
33
Q: Do hairs grow and/or stay attached forever?
Most hair is shed periodically in a molt, which is essential to survival.
34
Q: What general lifestyle factor may have contributed to some key characteristics developing in early mammals? Which characteristics?
The nocturnal lifestyle of early mammals may have contributed to the development of endothermy and hair.
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Q: Difference between mammals and, e.g., reptiles, in the attachment of the head to the neck.
In mammals, the occipital condyle (condyle = ball of ball-and-socket joint) has two points of contact to the first neck or cervical vertebrate.
The reptilian skull is attached to the spine by a single point of contact.
36
Q: How do mammal teeth develop/change/get replaced as the animal grows? How does this occur to other toothed vertebrates?
Mammals have two sets of teeth
-First emerges soon after birth (often called 'milk teeth')
-Acquire a larger set as an adult (both size and count increase to fill larger jawbones)
-Some exceptions in mammals. Elephants, kangaroos, and manatees have teeth that are continuously replaced. In some marsupials, only a subset of the teeth are replaced by "adult" teeth (from 3rd premolar back).
In all other toothed vertebrates, e.g., reptiles, teeth just keep coming, no matter how many are lost there is always another one ready to take its place.
37
Q: Are there any mammals without teeth? How do they consume food?
Yes, pangolins, monotremes, anteaters, and some whales.
Pangolins and anteaters have long sticky tongues for capturing ants and other insects.
Anteater tongue is long and sticky, and covered with spines. Flicks its tongue deep inside an ant colony, and the ants inside are glued to the sticky surface. It then grinds the ants against hard growths inside its mouth. Have also been known to swallow rocks to crush the ants in their tough stomach.
38
Q: Which kinds of mammals have the most diversity in how their feet contact the ground?
Mammals that run
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Q: Three basic types of foot-ground contact
Plantigrade- heel and toes both touch the ground (e.g., squirrels, rabbits, bears, raccoons, humans)
Digitigrade- heel is off the ground and only the toes touch (e.g., cats, dogs, wolves, birds). Tend to move more quickly and quietly.
Unguligrade- walking is on the tip of the digit, hoof, or nail (usually exhibited by hoofed animals, e.g., horses and cattle)
40
Q: What adaptation gave mammals a distinct endurance advantage over reptiles? How has this affected mammals?
Four-chambered heart.
Allows for much longer endurance to feed the oxygen demand of the tissues.
Mammals were able to actively hunt down prey or elude predators.
41
Q: Characteristics of mammal skin
Two layers
Packed with glands that serve multiple functions (e.g., sebaceous, mammary, sweat; details on separate cards)
42
Q: Sebaceous glands
Located at hair follicles.
Secrete the oily, waxy substance that lubricates and waterproofs the skin and hair.
Protect the body against germs. Secretions prevent the growth of bacteria.
Secrete scents or chemicals to help mammals communicate. (Pheromone details on separate card.)
Responsible for the acne that one has during puberty.
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Q: Discuss how mammals use scent for communication.
Scent glands of certain mammals secrete an often oily material of distinctive odor.
Scent plays a major role in many species including marking territory, cohesion of the group, communicating sexual fertility, and attracting mates.
Scent sources: Urine, feces, glandular marking.
Tree marking and rubbing are practiced by the deer family and the cattle, sheep, goats, and antelope family.
Some mammals have Flehmen response which employs VMO/Jacobson's organ (details on separate card).
44
Q: Pheromone
A secreted or excreted chemical factor that triggers a social response in members of the same species. (example uses on separate card)
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Q: Uses of mammal pheromones
Secreted by the sebaceous glands.
Trigger a social response in members of the same species.
Released in response to stress, alarm, danger, and sexual fertility.
You can observe ungulates and felids using their Jacobson's organ (vomeronasal organ, or VMO) to pick up pheromones. (details on separate card)
46
Q: Flehman response
Behavior whereby an animal curls back its upper lips exposing its front teeth, inhales with the nostrils usually closed and then often holds this position for several seconds. The behavior facilitates the transfer of pheromones and other scents into the vomeronasal organ (VMO or Jacobson organ) located above the roof of the mouth via a duct which exits just behind the front teeth of the animal. This is seen in ungulates and felids.
47
Q: Sweat glands-- What do they do? Who has them? Benefits?
Produce a liquid that evaporates off the skin to aid in temperature control.
Maintaining constant body temperature allows an organism to function effectively in a broad range of environmental conditions.
Only mammals sweat, but not all mammals have the same number of sweat glands.
Canids (dogs) posses very few sweat glands and cool primarily by panting.
A few mammals lack sweat glands (hippos, rinos, pigs, whales, dolphins, porpoises). Hippo spends most of its time in water, which helps regulate body temperature. Rhinos and pigs frequently roll in mud to cover their skin in order to cool themselves and protect from insects and parasites. Marine mammals depend on surrounding water to regulate temperature.
48
Q: Which animals have the sharpest hearing? Discuss.
Thanks to the middle ear and its three bones, mammals have the sharpest hearing on Earth and the greatest diversity of listening styles.
Bats and dolphins can detect ultrasonic pressure waves.
Elephants and humpback whales that can hear infrasound.
Also excellent at detecting very quiet sounds.
Excellent hearing helped early mammals which were probably nocturnal. Even today most mammals prefer to come out after dark.
49
Q: Evolution of the bones involved in mammal hearing
During mammalian evolution, the single middle ear bone of the reptile was combined with one lower jaw bone ('articular') and one upper reptilian jaw bone ('quadrate') forming the three mammalian middle ear bones.
Reptiles have one middle ear bone, while the upper and lower jaws contain several bones not found in mammals.
Improved hearing occurred in parallel with the evolving jaw and dentition in mammals.
50
Q: Name some factors that allow mammals to adapt to and thrive in diverse environments/niches (nearly every ecosystem on Earth)
-Endothermic (don't have to rely on environment to regulate temp; can inhabit regions with extreme temps and remain active in cold)
-Heterodonts (different kinds of teeth help adapt to different food sources)
-Fur allows for environmental adaptation (help keep warm, help keep cool, camouflage, protection)
51
Q: Hibernation
A state of inactivity and metabolic depression in endotherms. Hibernation is characterized by low body temperature, slow breathing and heart rate, and low metabolic rate.
Often occurs during cold periods when food becomes scarce.
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Q: True hibernation vs. torpor
Hibernation:
- a period of dormancy or inactivity occurring in cold seasons
- metabolic processes are greatly slowed as well as heart-rate, breathing
- body temperature may drop
- sleep to unrousable deepness
- used to conserve energy and cope with food shortages that occur in the winter
- during hibernation, stored body fat is used up at a relatively slow rate.
- found in many rodents, some bats, some insectivores
Torpor:
- a deep sleep, lighter than hibernation
- awaken more quickly than with hibernation; frequently wake and even move around outside
- heart rate, breathing, metabolic rate, and body temperature, although reduced, are significantly higher from a true hibernator
- E.g., during hibernation, ground squirrel's body temperature drops to near freezing, but bears reduce their body temperatures by only ~10 degrees.
- appears to be *involuntary*, unlike hibernation
- allows them to respond to needs of young which they deliver during this period
53
Q: Term for prolonged torpor or dormancy of an animal during a hot or dry period
Estivation
54
Q: Do reptiles hibernate?
Brumation- the hibernation-like state that cold-blooded animals utilize during very cold weather.
Physiological changes which are independent of body temperature occur.
55
Q: Besides hibernation/torpor, how else do mammals deal with cold seasons and seasonal resource scarcity?
Migration
56
Q: Examples of mammal migration
Caribou herds travel south for the winter and back north for the summer.
Gray whales migrate up to 12,500 miles/year to find krill, plankton, or shrimp.
The Great Migration of Africa occurs each year; over a million wildebeest along with gazelle and zebra move towards better grazing areas and water supplies.
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Q: How many mammal species does the IUCN Red List consider as being at some risk of extinction?
About 1000 species, roughly 25% of all known mammals.
58
Q: Compare the collective biomass of domesticated vs. non-domesticated land mammals.
Domesticated mammals constitute the vast majority of the biomass of land mammals and dramatically affect human's ecological footprint.
Some estimate that the biomass of domesticated mammals may be 30x that of wild land mammals.
59
Q: What is a keystone species? Give examples.
-A species which has a disproportionately large effect on its natural environment relative to its abundance.
-Plays a unique or critical role in the way an ecosystem functions and whose removal would result in dramatic, cascading changes to the ecosystem, even ecosystem collapse
-Often a keystone species is a top predator.
-Many mammals have become keystone species
-Example: Wolf. By regulating large ungulate populations, wolves enable many other species of plants and animals to flourish. They keep the ungulate populations healthier, prevent them from becoming too abundant, and prevent overgrazing. In this regard, wolves initiate a domino effect -- "touching" songbirds, beaver, fish, and butterflies.
-Example: Bees
60
Q: Which groups of animals are the nonplacental mammals?
Monotremes and marsupials.
Monotremes: order within Mammal class.
Marsupials: infraclass within Mammal class with multiple orders.
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Q: Where are most of the nonplacental mammals? Why?
Isolated from the placental mammals, Australia became home to the majority of nonplacental mammals. Marsupials of Australia came to occupy many of the ecological niches placental animals occupy elsewhere in the world.
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Q: Monotremes
The oldest living group (order) of mammals. Considered the most primitive of mammals.
Lay eggs. Only mammals not to give live birth.
Mother has no nipples. Instead monotremes secrete milk through mammary gland openings in the skin and the baby laps it off the mother's hair on her abdomen.
All found in Australia or New Guinea.
There are only two surviving families, the platypus (family: Ornithorhynchidae) and 4 species of echidna (spiny anteaters) (family: Tachyglossidae).
Leg bears a spur in ankle region. Spur is not functional in echidnas, but contains a powerful venom in the male platypus.
Means "single opening" in Greek, referring to the single duct for urination, defecation, and reproduction (egg-laying).
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Q: Egg care/development in monotremes
In echidnas, the egg is carried in a pouch on the female's belly (about 10 days) until the young hatches, at which point the barely-developed young must find a mammary gland and latch onto it for nourishment.
In the platypus, the female retires to a burrow in the bank of a river or pond. Lays eggs and incubates them for about 10 days. Babies are not fully formed when they hatch; they lack hair, claws, and a sense of sight.
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Q: Besides egg-laying, is there any reptile-like characteristic that monotremes retained?
Reptile-like gait, with legs on the sides of, rather than underneath, their bodies as in other mammals.
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Q: Marsupials
Infraclass within the mammalia class.
Lack a true placenta. Female develops a kind of yolk sac in her womb, which delivers nutrients to the embryo.
Double reproductive tract and give (live) birth to a relatively undeveloped, immature embryo after a short gestation.
Embryo comes out blind, hairless, and w/ undeveloped hind legs, but limbs formed enough to pull itself through the mother's fur up from the vagina to the pouch, where it finds a nipple and attaches itself where it develops further for several weeks/months.
Baby (joey) does most of its development attached to a teat, which in most cases is in a pouch.
66
Q: How big is a marsupial embryo when it makes the journey to the nipple?
The size of a jellybean
67
Q: Name mammals that occupy similar ecological niches as the kangaroo, Tasmanian devil, and koala, but are found outside of Australia and, as such, don't compete with the marsupials.
Kangaroo: Deer and antelope are larger grazing animals.
Tasmanian devil: Wolverine.
Koala: Sloths.
68
Q: Term for infant marsupial
Joey
69
Q: When is a Joey able to exit the pouch? Does it ever go back?
Joey becomes able to regulate their body temperature at about the same time weaning occurs, which is when the joey will begin to come out of the pouch.
Joeys will continue to use the pouch to sleep or for safety even after exploring outside.
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Q: Embryonic diapause
Period of arrested (paused) development of an embryo at the stage of blastocyst (70- to 100-cell stage).
Allows emergence of young to coincide with desirable conditions (e.g., available teat after previous joey weaned).
Female can mate shortly after giving birth, fertilized embryo develops into blastocyst, then becomes dormant until the previous joey is done nursing, at which point it resumes development (33 days to emerge at that point).
May result in having three young in different stages of development dependent on the mother at one time. Female kangaroo/wallaby/wallaroo can have three offspring in three different stages of development- the blastocyst, the joey in the pouch, and a partially weaned offspring (referred to as young-at-foot). The female produces different milk for the joey and the young at foot (the latter is richer).
Embryonic diapause is found in some Kangaroos, wallaroos, wallabies, and many other mammals.
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Q: Threats to marsupials
Most of Australia's wildlife is endemic (found nowhere else in world)
Australia is the country with the highest *mammal* extinction rate.
According to IUCN Red List in 2016, Australia is in the top five for extinction of animal and plant species, and the top 10 for endangered and threatened species.
Marsupials evolved in Australia without the competition from placental mammals.
Placental mammals were introduced by settlers (dingos, feral cats, rabbits) and have had a negative impact on native species and the environment due to predation, competition, etc.
Expanding human settlement and agriculture have altered the habitat of some marsupials and some species are endangered by the loss of habitat. Grazing sheep have altered or eradicated certain habitats resulting in the decline of numerous small marsupials, while allowing the large kangaroos to expand their range.
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Q: Examples of specific effects of specific human-introduced species in Australia
Competition with dingos is thought to have eliminated the Tasmanian wolf from the Australian mainland.
Rabbits overgraze leading to erosion and loss of plant diversity. They also compete with native animals for food and shelter. Has been devastating
73
Q: Are koalas endangered?
Koalas are considered threatened ('vulnerable') on the IUCN Red List.
Certain populations are endangered (changed in 2021).
Koalas are protected.
74
Q: Placental mammals (overview, general characteristics)
Infraclass within the mammalia class.
Have a placenta, which facilitates exchange of nutrients and wastes between the blood of the mother and that of the fetus.
Young develop within the mother's womb; placenta provides oxygen/nutrients.
Longer gestation period than the marsupials.
All bear live young.
Varying amounts of parental care depending on the species.
Requires a greater maternal investment of time and energy than non-placental, but results in benefits to the infant. Babies are protected inside the mother for a longer period, allowing for more complex development
Placental reproductive system is considered more advanced than that of monotremes and marsupials.
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Q: General benefits and downside to placental mammals' live-birth method as compared to, e.g., egg-laying or marsupials.
Embryos at lower risk to temperature change, desiccation, oxygen deprivation.
When born, placental mammals are much more developed than marsupials due to longer gestation.
Downside: Extra costs to parent. E.g., physical toll.
76
Q: Are newborn placental mammals precocial or altricial?
The amount of time it takes placental mammals to fend for themselves varies widely between species.
-Most primates, all hoofstock, marine mammals are born precocial. Can move around on their own shortly after birth. Camouflage colors and cryptic behaviors to avoid predation while trailing their parents and nursing until thay are capable of feeding on their own. Hoofstock need to be able to quickly get up and move with the protection of the herd.
-Most rodents, many carnivores, and bats are born altricial. Blind, sometimes hairless, weak-limbed young that must be cared for.
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Q: How does the human gestation period compare to other primates and the rest of the animal kingdom?
Humans have a relatively long gestation period compared to the rest of the animal kingdom and are born underdeveloped compared with other primates.
78
Q: Name some orders of placental mammals.
(these categories seem to be frequently changing with new scientific discoveries, but looks like there are about 20 orders of placental mammals)
Rodents - Rodentia
Bats - Chiroptera
Primates - Primates
"Carnivores" - Carnivora
Even-toed ungulates - Artiodactyla
Odd-toed ungulates - Perissodactyla
Whales, dolphins, porpoises - *Cetacea; *considered by some to be infraorder within Artiodactyla
Rabbits, hares, pikas - Lagomorpha
Golden moles, otter shrews, tenrecs - Afrosoricida
Hedgehogs, gymnures, solenodons, desmans, moles, shrew-like moles, true shrews - Eulipotyphla
Armadillos - Cingulata
Treeshrews - Scandentia
Elephant shrews - Macroscelidea
Anteaters and sloths - Pilosa
Elephants - Proboscidea
Aardvarks - Tubulidentata
Hyraxes - Hyracoidea
Dugongs and Manatees - Sirenia
Colugos - Dermoptera
Pangolins - Pholidota
79
Q: Anteaters and sloths - order Pilosa (general overview)
Pilosa means "hairy".
Anteaters lack teeth. Sloths lack incisors and canines and thus appear to be toothless.
Mainly solitary.
Found in Central and South American.
Highly specialized.
Vertebrae/pelvis adaptions provide high stability to the pelvic region for burrowing/digging: Extra articulations between the vertebrae of the lumbar region. Pelvis connects with more of spine than in other mammals.
Large, curved claws and powerful forelimbs. The sloth evolved these for climbing.
80
Q: One key benefit of a sloth's upside down lifestyle
Avoids the energy needed for balance when moving along the tree branches.
81
Q: Which group of mammals has the most species?
Rodents. 40% of all mammal species.
82
Q: Rodents - order Rodentia (general overview)
Large, sharp, chisel-shaped incisors (2 upper, 2 lower) that grow continually and have to be worn down by gnawing.
Most are small animals with robust bodies, short limbs, and long tails.
Mainly herbivores, but some species will eat invertebrates.
Extremely adaptable and occupy a variety of niches.
High reproductive rate. Allows them to keep populations stable.
Order of mammals with most species - 40% of all mammal species.
83
Q: Are rats and mice herbivores, omnivores, or carnivores?
Rats and mice are considered omnivores.
84
Q: Rabbits, Hares, Pikas - order Lagomorpha (general overview)
All are herbivorous.
Elongated ear pinnae for improved hearing.
Rear legs adapted for jumping.
Like rodents, have gnawing, chisel-shaped incisors that grow throughout their life, but rabbits have TWO pairs of upper incisors (two smaller, peg teeth behind the outer upper incisors).
Found almost worldwide.
High reproductive rates. Up to 6 litters of 12 young annually. Probably most young per year of any mammal. Induced ovulators. (Similar to rats. Tenrec can have >30 per litter but only 2 litters per year.)
Extremely adaptable. Opportunistic feeders. Occupy a variety of niches: arboreal, terrestrial, fossorial (burrowing), and semi aquatic.
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Q: Induced ovulator
Species where the act of breeding causes female's ovaries to release eggs.
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Q: What might an observation of a rabbit's ears tell you about its habitat?
Species in warmer climates have longer ears for heat evaporation while those in cooler climates have reduced ears to help maintain their body temperatures.
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Q: Ungulates (general overview)
Hoofed animals, most walk on tips of toes (unguligrade).
Comprise vast majority of world's large herbivores.
Vast majority are large herbivores. Grazers and browsers.
Eyes on the side of the head; prey animals.
Precocial young.
Classified in two Orders: Perrisodactyla and Artiodactyla
The Order/Infraorder Cetacea (whales and dolphins) is sometimes merged with the Artiodactyla forming new Order Cetartiodactyla. Whales evolved with the Artiodactyla with the hippo being their closest relative. Some sources consider Cetacea an infraorder within Artiodactyla.
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Q: Difference between grazers and browsers.
Grazer: type of feeding where an animal eats the grass on the ground.
Browser: type of feeding where an animal eats the vegetation on bushes and trees.
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Q: Examples of ungulate grazers and browsers.
Grazers: zebras, horses
Browsers: black rhino, hippo
Grazer and Browser: Greater one-horned or Indian rhino
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Q: Differences between molars of grazers vs. browsers.
Molars of grazers are large and flattened, with a series of ridges to help grind up the plant material.
Browser molars are also large and flattened but tend to be identified by a series of peaks and valleys to help crush and grind the more fibrous plant material.
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Q: One key way that multiple herbivorous ungulates reduce competition while coexisting? Example?
Resource partitioning.
Rely on different parts of the plant(s)---occupy separate niches.
E.g., zebras like the course, older tips of the grass. Wildebeest preferred the more tender center part of the grass blade.
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Q: How are ungulates classified? When did these groups share a common ancestor and how did they develop from there?
Two different Mammalian Orders based on the number of toes.
The two Orders (Perrissodactyla/odd-toed and Artiodactyla/even-toed) diverged from a common hoofed ancestor 60 million years ago.
Odd: Middle toe is larger and the weight bearing runs through the middle digit (digit III). First to evolve and were the dominant large herbivores at first.
Even: Third and fourth digits remain large and bear weight. As grasses evolved, Artiodactyla were better able to adapt to coarse, low-nutrition diets, (through rumination) and soon rose to prominence over the Perissodactyls. Have come into their prime only in recent times, surpassing the odd-toed ungulates in numbers.
(In both groups, the degree to which non-weight bearing toes remain varies. E.g., horses have one toe and only tiny vestigial remnants of two on either side.)
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Q: Examples of odd- and even-toed ungulates.
Odd: Rhinos, horses, zebras, donkeys, tapirs. Native to Africa, Asia, and Americas.
Even: Hippos, sheep, goats, camels, pigs, peccaries, cows, bison, buffalo, deer, pronghorns, giraffes, antelope, camels, llamas, guanacos, alpacas, vicunas, greater kudu, eastern mountain bongo.
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Q: Odd-toed Ungulates - Order Perissodactyla (general overview)
Simple stomachs; hindgut fermenters.
Unguligrade gait (walk/run on toes, which have developed hooves).
Usually a single offspring.
First to evolve among the Ungulates.
(see ungulates overview card for characteristics common to odd & even toed ungulates)
(separate card for toe distinction)
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Q: Cellulose
An organic compound that forms the main component of the cell walls of plants; it gives wood its remarkable strength.
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Q: Since mammals lack the enzymes needed to break down cellulose, how do they do it?
Mammals can only access a small portion of the nutrients in vegetation by themselves. They are aided in cellulose digestion by microorganisms residing in the digestive system, either in the stomach (foregut fermentation) or in the intestines (hindgut fermentation). Rumination is a process using foregut fermentation. (details on separate cards)
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Q: What are ruminants? Benefits of rumination? Contrast with hindgut fermentation
Ruminants have a four-chambered stomach with specialized microbes to help break down the cellulose before the nutrients get absorbed in the intestines.
Ruminants start by summarily chewing the food. They then regurgitate it later to chew it properly for a longer time.
A form of foregut fermentation. (There are foregut fermenters that are not true ruminants.)
Food is already broken down when it reaches the intestines; absorption of nutrients can occur along entire intestines.
Benefit: Can consume a large quantity of food and later process the plant material (in safety) to extract maximum amount of energy.
Benefit: Can consume foods that other animals wouldn't be able to digest or retrieve nutrients from.
Hindgut fermentation:
Hindgut fermenters (which have single-chambered stomach) usually have longer intestines, and microbes are in the intestinal tract, or in the cecum. (koalas have a 7' cecum for digestion)
Since the microorganisms are located mostly in the cecum of the large intestine, the animal doesn't have the full length of the intestines for absorption of the extracted nutrients. To make up for this inefficiency, these species must eat larger quantities of food.
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Q: Where are most nutrients absorbed in mammal digestion? Is this different in ruminants?
Small intestine absorbs most nutrients in mammals, including in ruminants.
In ruminants, food is already broken down when it reaches the intestines; absorption of nutrients can occur along the entire length of intestines. In hindgut fermenters (not ruminants), since the microorganisms are located mostly in the cecum of the large intestine, the animal doesn't have the full length of the intestines for absorption of the extracted nutrients.
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Q: Ruminant examples
Deer, giraffe, antelope, sheep, goats, buffalo, and cattle.
Camels, guanacos, alpacas (ruminate but have three-chambered stomach).
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Q: What development in Earth's history was a key factor in the evolution of rumination?
From the Miocene onwards, grasses covered the plains and provided a new food source.
Rumination provided a faster, more efficient method of extracting greater nutrition from low quality vegetation.
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Q: Major factor contributing to the diversity and success of even-toed ungulates?
Diversity of even-toed ungulates and their success as ruminants is attributed to their highly efficient digestive system.
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Q: Connection between rumination and climate change.
Humans are responsible for the existence for large numbers of domesticated ruminants.
Carbon dioxide and methane gas are byproducts of foregut fermentation.
Increased levels of these gasses (due to humans raising large numbers of ruminants) trap heat in the lower levels of the atmosphere resulting in global warming.
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Q: Difference between odd-toed and even-toed ungulate digestion?
Odd-toed ungulates: Simple stomachs. Hindgut fermenters - digest grasses and plant cellulose in intestines; microorganisms that help break down cellulose are housed after the stomach in the intestines. This process is inefficient. Bulk feeders; they ingest large quantities of low-nutrient food.
Even-toed ungulates: Mainly ruminants with four-chambered stomach and foregut fermentation by microbes. Some ruminants have 3 chambers. A few even-toed ungulates are not ruminants.
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Q: Even-toed Ungulates - Order Artiodactyla (general overview)
Distributed worldwide.
Mainly ruminants, with four chambered stomach and foregut fermentation by microbes. (Some ruminants have 3 chambers.)
1-2 precocial offspring, except pigs which have litters
Scents are important in communication.
Most are herd or group animals.
(see ungulates overview card for characteristics common to odd & even toed ungulates)
(separate card for toe distinction)
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Q: Name some even-toed ungulates that are NOT ruminants.
Pig and peccary have two-chambered stomachs and are not ruminants.
Hippos have three-chambered stomach and are non ruminants.
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Q: What species of rhino do we have at the SF Zoo?
Black rhino and greater one-horned rhino
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Q: Order Carnivora (general overview)
Mainly meat-eaters (carnivores), but some omnivores and a few herbivores.
Adaptations for pursuing and consuming prey.
Distinguishing features: long canines and carnassial teeth (jaw/teeth details on cards in biofact skulls section).
Most have acute vision with forward facing eyes, well developed sense of smell, and acute hearing.
Carnivorans have simple stomachs and undeveloped ceca as meat is easy to digest.
Reproductive strategies include delayed implantation and induced ovulation.
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Q: Where did the name for the order carnivora come from?
Not all species in carnivora eat meat.
Name comes from their carnivorous ancestry. The first carnivoran was a carnivore.
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Q: Which carnivores have less developed/shorter carnassial teeth?
The length of the carnassials is determined by the size of the animal, how much its diet is carnivorous, and the size of the chunks of meat it can swallow.
In bears and pinnipeds (seals, sea lions, and walruses ), carnassial teeth are not well developed.
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Q: How do species in carnivora compensate for the reduced field of view of forward-facing eyes?
Mobile eyes and mobile necks.
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Q: Do carnivoran species tend to live in groups or alone? Name two reproductive adaptations to this lifestyle.
Carnivoran species tend to lead solitary lives.
They may not come across a mate frequently. Delayed implantation allows these species to time birthing and/or weaning when food is most abundant. Embryo does not immediately implant in uterus. Maintained in state of dormancy.
Induced ovulation is when the females release an egg during or shortly after copulation. Allows females to be receptive to a mate when they cross paths.
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Q: Delayed implantation. Animal examples.
Embryo does not immediately implant in uterus. Maintained in state of dormancy.
Allows species that lead solitary lives and may not come across a mate frequently to time birthing and/or weaning when food is most abundant.
Bears usually mate when first come out of dens in spring. Egg will only implant if mother has found sufficient food before she dens up. Times emergence from den with weaning of cubs when food resources are plentiful.
Seals come ashore to give birth and molt. Delayed implantation may serve to enable seals to combine birth and mating into a single period and avoid potentially dangerous period spent ashore.
Rodents also exhibit delayed implantation.
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Q: Induced ovulation
Females release an egg during or shortly after copulation. Allows females to be receptive to a mate when they cross paths.
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Q: Two suborders of carnivora - describe the split. How are they distinguished?
Caniformia and Feliformia
Carnivora order split (early) into dog-like and cat-like forms about 50 MYA.
Split began with a change in dentition; the cat-like forms became more highly specialized predators.
Differentiated based on the structure of their ear bones and cranial features.
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Q: Suborder Caniformia (general overview)
Dog-like forms within order carnivora. One of two suborders.
Includes canines, bears, raccoons, mustelids, and pinnipeds. (full list on separate card)
Long snout. Use sense of smell to hunt and to avoid predators.
Large canines.
Teeth for crushing, all-purpose omnivore teeth. Maintained flat grinding molars of their herbivore ancestry.
Non-retractable claws.
Long legs.
Many hunt in packs and are social animals, giving them an advantage over larger prey.
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Q: List the families in Suborder Caniformia.
Canidae (dogs, wolves, jackals, foxes).
Ursidae (bears, giant panda).
Procyonidae (raccoons, coatimundi).
Ailuridae (red panda).
Mustelidae (otter, wolverine, weasels and badgers).
Mephitidae (skunks - Note: formerly of Mustelidae Family).
Pinnipedia clade w/three families:
Phocidae (earless seals, true seals),
Otariidae (eared seals, sealions),
Odobenidae (walrus).
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Q: List some SF zoo caniforms.
Red panda, black & grizzly bear, North American river otter, wolverine, and gray fox.
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Q: Are there any truly carnivorous bears?
Yes. Only the polar bear.
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Q: Canidae Family - Dogs (general overview)
Order: Carnivora; Suborder: Caniformia; Family: Canidae
More omnivorous than many carnivores. Eat invertebrates, plant matter, carrion, and prey they kill.
Use good sense of smell to avoid predators and find prey.
Adapted more for endurance than speed (relative to felids), catch prey by pursuit over long distances in relatively open terrain.
Grab for nape of neck and tackle prey to the ground.
Wider field of vision than felids.
Moderate body size due to pack-hunting.
Group/social structure based on mated pair and offspring. (generally the larger species)
Hunting in packs allows canids to capture species much larger than themselves.
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Q: In general, who has a better sense of smell, dogs or cats?
Dogs can smell at least 4x better than cats based on the number of olfactory receptors.
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Q: Suborder Feliformia (general overview)
Cat-like forms within order carnivora. One of two suborders.
Shortened snout compared to caniforms.
Fewer teeth, larger canines, more specialized carnassials compared to caniforms.
Gap behind the canine so that the teeth can sink all the way to their gums.
Retractable claws (exception: Cheetah)
Tend to be more carnivorous.
Generally ambush hunters.
More are digitigrades (many caniforms are plantigrade).
Many are arboreal or semi-arboreal.
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Q: List families within Feliformia.
Felidae (cats, tiger, lion).
Viverridae (civets & genets).
Herpestidae (meerkats, mongooses, fossa).
Hyaenidae (hyenas).
Eupleridae (fossa, other Madagascar carnivores).
Nandiniidae (African palm civet; single species).
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Q: List some SF zoo species in suborder Feliformia.
Meerkat, jaguar, snow leopard, ocelot, African lion, and a fossa.
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Q: Felidae Family (general overview)
Highly specialized predators w/adaptations for pursuing and consuming prey. (details on separate card)
Most have acute vision with forward facing eyes, well developed smell (for close range examination; not as good as dogs, bears), acute hearing.
Nocturnal predators. Also crepuscular. Often hunt at early dawn.
Tapetum lucidum for night vision (details on separate card).
Wider peripheral vision than dogs. Better vision at close range. Largest eyes of the Carnivorans.
Obligate carnivores. Short digestive tract.
Tongues are rough due to small bumps (papillae).
Grouped into "big" and "small" cats.
Group affiliation based on mother and daughters.
[many more details in feline section]
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Q: Describe feline adaptations for pursuing & consuming prey.
Eyes:
-Eye sockets face forward. Gives better depth perception to pursue prey. Eyes are set wide allowing a wider field of vision than that of humans.
-Eye sockets large in relation to skull may suggest an animal is nocturnal (as in cats). Larger eyes = better vision in dim light.
-Reflective layer behind retina called a tapetum lucidum (Latin for "shining layer"), which improves night vision. Layer reflects the light back through the retina causing the characteristic "eye shine".
Mouth:
-Sharp teeth (details on separate card in feline section)
-Felines typically possess a shortened snout/jaw giving them a powerful bite force to restrain their prey.
Paws:
-Large paws: good for climbing and gripping; act as shock absorbers when jumping; spread out weight to help them walk more quietly when stalking prey; can act like snowshoes as in snow leopards.
-Retractable, sharp claws to bring down prey. Retractable claws prevent wear while walking; keep them sharp. (Note: cheetahs do not have retractable claws.)
Other:
-Camouflage.
-Very flexible spine (more thoracic and lumbar vertebrae than humans) allows greater agility when chasing down prey.
-Able to rotate and bring the soles of their front paws together.
-Tail is important for balancing the weight of the body especially when they are pursuing prey.
-Thick whiskers that allow them to feel things that they may not see.
[duplicate card: mammal, feline sections]
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Q: When do cats hunt?
Nocturnal predators. Also crepuscular. Often hunt at early dawn.
[duplicate card: mammal, feline sections]
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Q: How are cat species broadly divided into groups?
Big and small cats; the differentiation is the hyoid bone, which connects the tongue to the roof of the mouth.
Note: "Big cats" are typically larger than "small cats" but this0. cannot be used to differentiate. The puma or mountain lion, despite its size, is not typically classified among the "big cats", as it cannot roar, lacking the elastic hyoid of the genus Panthera, the large cats.
[duplicate card: mammal, feline sections]
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Q: Describe the hyoid bone in big cats vs. small cats
Hyoid bone connects the tongue to the roof of the mouth.
In big cats, the hyoid has an elastic segment, while that of small cats is hard all over.
The hyoid bone allows big cats to produce a roar and prevents them from purring in the same manner as small cats. (The exception is the snow leopard who is unable to roar but has a hyoid bone like the big cats.)
[duplicate card: mammal, feline sections]
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Q: Threats to mammals (general)
Habitat loss. (due to, e.g., human encroachment, climate change)
Being hunted for bushmeat, trophies, consumer products, traditional Chinese medicine, and to get rid of nuisance animals.
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Q: For each of these mammals, give its order and whether it ruminates: Black Rhino, E Mt Bongo, Baird’s Tapir, Grant’s Zebra, Pygmy Hippo.
Black Rhino: Perissodactyla, NONruminator
Eastern or Mt. Bongo: Artiodactyla, ruminator
Baird’s Tapir: Perissodactyla, NONruminator
Grant’s Zebra: Perissodactyla, NONruminator
Pygmy Hippo: Artiodactyla, have multi-chambered stomach (foregut fermentation) but NOT a ruminant.
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Q: Order Carnivora defining feature
Large canines and carnassial teeth
