Zoology Lab 8
Claws
Composed of an unguis above and subunguis below, claws are typically sharp and curved downward. Claws are typically immobile but most felids have developed muscles that retract the claws when not in use. Claws function in traction and stability in running mammals, protection, excavation, climbing, and holding/killing prey.
*Order Carnivora -
Dog-like forms, Bears, Racoons, Weasels, Skunks, Seals, Sealions and Walruses (160 spp.) Cat-like forms, Civets, Mongooses, Meerkats and Hyenas (~130 spp.) Look for - Large canine teeth - sectorial cheek teeth (carnassial pair in some) - large sagittal crest on top of skull - long sharp claws.
Order Sirenia -
Dugong and Manatees (4 spp.) One of two fully aquatic orders of mammals. Sirenians are coastal dwelling herbivores. Look for - heavy skull with no incisors or canines - tip of upper and lower jaws are laterally compressed into a flange for attachment of muscular lips - orbits nearly closed - large nasal opening.
Order Macroscelidea
Elephant shrews (19spp.) Fast running insectivores of Southern Africa, elephant shrews are neither elephant nor shrew but are more closely related to the former. Look for - Long proboscis-like snout - large vibrissae and eyes - long legs and hind feet - long tails lacking fur.
Order Proboscidea
Elephants (3 spp.) Large terrestrial mammals with elongate trunks and paired tusks. Look for - Large skull with prominent nasal opening - upper incisors modified as pair of tusks - lack canines - lower jaw tip flanged for attachment of large lip muscles.
Order Dermoptera -
Flying Lemurs or Colugos (2 spp.) Gliding herbivores of tropical Asia. Look for - patagium of skin between neck/forelimb/hindlimb and tail - eyes face forward - long thin limbs - lower incisors form a tooth-comb for grooming.
*Order Eulipotyphla
Hedgehogs, Moles and Shrews (~480 spp.) Small to medium ground dwelling insectivores, omnivores and carnivores. Look for - pointed snout - moles with educed extremities and very robust claws - hedgehogs with spines - shrews mouse-like but with pointy noses.
Order Hyracoidea -
Hyraxes (7spp.) Stout-bodied herbivores that inhabit rocky areas of Africa and the Middle East. Look for - stout-bodied - feet with thick pads - hoof-like claws - numerous vibrissae along entire body - small rounded ears - reduced tail.
Order Diprotodontia
Koala, Wombats and Kangaroos (~30 spp.) The largest and most commonly known marsupial Order, diprotodontids are restricted to Australia, New Zealand and New Guinea. Most are herbivores, though some are omnivorous and some extinct members were carnivorous. Look for - two incisors of the lower jaw are procumbent (project forward) - presence of diastema - lack canine teeth - relatively small braincase - dorsal edge of the zygomatic arch (cheekbone) nearly as high as the top of the braincase.
Mustela nivalis -
Least weasel Look for - elongate body - small weasel - tail fairly short (not bushy) - fur countershaded or cryptic in winter
*Order Primates -
Lemurs, Monkeys, Apes and Humans (~450 spp.) Mostly arboreal, primates are distributed worldwide and include herbivores, insectivores and carnivores. Look for - Eyes facing forward - rostrum reduced in monkeys, apes and humans - brow ridge above the eyes - cranium large and domed - claws replaced by nails - most with opposable thumbs.
Prototheria
Mammals that reproduce by egg-laying, then nurse young from nipples. The Australian platypus and echidna are the only living monotremes.
Lontra canadensis
Northern river otter Look for - smooth shiny pelage - elongate body and neck - reduced external ears - thick muscular tail - numerous vibrissae around mouth.
Ossicones
Not true horns, giraffe horns are permanent, unbranched bony processes of the skull covered by skin
*Order Perrisodactyla
Odd-toed ungulates - Horses, Rhinos and Tapirs (17 spp.) Perrisodactyls bear their weight primarily on the third toe. Look for - upper incisors present - diastema in upper and lower jaws - elongate head shape - lower jaw with deep (dorsoventrally tall) mandible.
Order Didelphimorphia
Opossums (~110 spp.) One of only two marsupial orders present in the Western hemisphere and the only one to reside within North America. Most Opossums are semi arboreal omnivores and possess both a prehensile tail and an opposable digit on their hind feet to aid in climbing. Look for - plantigrade feet - marsupium - fur lacks guard hairs - tail long and scaled - long snout -prominent saggital crest (middle of dorsal cranial surface).
*Order Lagomorpha
Rabbits, Hares and Pikas (~100) Small to medium herbivores with large ears and ever-growing incisors. Look for - Area in front of orbit with lace-like bone and numerous fenestrations - double upper incisors (two small and peg-like just behind large ever-growing pair) - rabbits and hares with large long ears, short tail and large hind limbs/feet - Pikas with large rounded ears - reduced tail - lack saltatory adaptations of rabbits/hares
*Order Rodentia
Rodents - Mice, rats, Gerbils, Voles, Lemmings, Beaver, Muskrat, Squirrels, Porcupines, Capybara and Guinea Pigs.(~2450 spp.) The largest mammalian Order and third largest vertebrate Order. Rodents are mostly small bodied herbivores though omnivory is common. Look for - ever-growing incisors of the upper and lower jaw - large diastema - lack canines - broad flattened area in front of orbit for jaw muscle attachment - tails often lack fur.
Order Pilosa -
Sloths and Anteaters (9 spp.) Mostly arboreal placentals of tropical central and South America. Look for - Xenarthrous processes (extra processes of lumbar vertebrae create intervertebral contact - Anteater with elongate toothless snout - Sloth with short snout and simplified /reduced teeth - both with elongate claws of the fore feet.
Order Scandentia -
Tree shrews (~20 SPP.) Arboreal omnivores with pointed snouts restricted to Southeast Asia. Look for - pointed snout - large round ears - somewhat plumose tail (not as plumose as red squirrel tail) - counter shaded pelage.
True Horns -
Unbranched and permanent, true horns are composed of a bony process with a keratinized covering or sheath. Horns may be present on both sexes or only in males. Because they are permanent, true horns may display seasonal growth rings.
Family Mustelidae
Weasels, badgers, otters, wolverine
Order Cetacea -
Whales (~63 spp.) One of two fully aquatic mammalian Orders. Two major radiations of whales exist; the Mysticeti (Baleen whales) and the Odontoceti (Toothed whales). Look for - homodonty or tooth loss - baleen replacing teeth in some - reduction in zygopophyses - loss of hind limb - front limb modified into flipper.
Gulo gulo
Wolverine Look for - relatively large - body not as elongate - limbs longer than other weasels - bushy tail - back lighter color with darker legs.
Disruptive
like so many striped schooling fishes, herding mammals like zebras employ dramatic patterns of contrasting colours in order to impede predators from defining the outline of one individual against the backdrop of the entire herd.
Seasonal colouration
many mammals undergo seasonal molts whereby coat colour is changed in order to blend in better with a changing environment.
Sebaceous glands
produce oily substances released into hair follicles. Oils condition the hair and help maintain properties of the pelage like water resistance.
Under hair
shorter and lacking in stiffness, under hairs are wavy and more numerous than guard hairs. Under hair functions as insulation.
Pelage
the entire covering of hair is called the Pelage). Another example of keratinized epidermis along with claws, nails and hooves, hair holds great functional significance for mammals as an insulating layer supporting their endothermic metabolism.
Camouflage
the juveniles of many mammals bear a striped or spotted coat which blends well with dappled sunlight under forest canopies. Many forest predators use this same pattern to conceal themselves from potential prey.
Guard hair
the outer covering of the coat is made up of longer, straight stiffer hairs with a smooth appearance. Guard hairs protect the skin from water and sunlight and may be raised as part of a treat display
Scutes
the plate-like scutes of armadillos are composed of a keratinous scaly covering on top of an interlocking series of dermal bones. Armadillos are the only extant mammals to possess dermal bones within the ski
Mammary glands
- A defining characteristic of mammals, mammary glands are likely modified sweat glands.
Hooves
- A large robust unguis encircles the entire digit and subunguis. Restricted to ungulates, hooves provide a highly durable interface with the substrate and enable ungulates to travel great distances at speed.
Order Tubulidentata
- Aardvarks (1 sp.) Medium bodied insectivores of Africa, the aardvark shares many features with anteaters relating to their specialized diet of ants and termites. Look for - reduced dentition of simple peg-like teeth - long snout - reduced pelage - large rabbit-like ears - pig-like snout - large claws - thick tail.
Countershading
- Secondarily aquatic mammals employ counter shading in the same manner as fishes and birds. It should be noted however that many terrestrial mammals are also countershaded.
Pronghorns
- Similar in structure to true horns, pronghorns differ in that the keratinized sheath is branched and shed annually. Both male and female pronghorns have horns.
Rhinoceras horn
- The only extant non-artiodactyl example of head ornamentation. Rhino horns are unbranched, permanent and composed of keratin with no bony core. Recent research has determined that deposits of calcium and melanin in the core of the horn provide greater resistance to wear near the centre. This leads to differential wear of the outer horn creating the distinctive shape and sharp point characteristic of rhino horns.
Order Monotremata
- egg laying mammals Platypus and Echidnas (5 spp.) All extant monotremes are toothless as adults and feed on invertebrates they locate using electro-receptors in their leathery bills. Look for - toothless and elongate jaw - Platypus with dorsoventrally flattened bill and tail - echidnas with long tubular jaw and reduced tail - platypus with shiny smooth pelage - echidna fur modified into protective spines - males with venomous spur on hind foot.
Spines/Quills
- independent evolution of spines or quills can be seen in monotremes, insectivores and rodents. Spines and quills vary considerably in shape, length root depth, but all are modified forms of hair
Scales
- known only in the pangolins, scales are large overlapping keratinous outgrowths of the skin. Pangolin scales are robust protection against predators.
Nails -
- present only in primates, nails consist of a broad flattened unguis with a greatly reduced subunguis present only at the tip. Unlike claws, nails are restricted to the upper surface of the digits and free up the tips of fingers which are highly innervated as tactile receptors.
Taxidea taxus -
American badger Look for - body wide and held close to the ground - contrasting facial markings - short tail.
Martes americana -
American marten Look for - elongate body - relatively large ears - face paler than body - bushy tail.
Antlers -
Antlers vary in shape but all are highly branched and composed of bone with no keratinized sheath. Antlers are shed annually and covered with highly vascularized skin (velvet) during the re-growth phase. Typically only seen in males, the caribou are the only species where both sexes have antlers.
Order Cingulata -
Armadillos (18 spp.) Armoured, ground dwelling insectivores, armadillos are the only extant mammals that possess osteoderms. Look for - distinctive carapace formed by osteoderms covered by thin scales - narrow snout with reduced peg-like teeth - robust spade-shaped claws.
*Order Chiroptera -
Bats (~1200 spp.) Flying mammals distributed worldwide. Bats include Frugivores (fruit eaters) insectivores and blood feeders. Look for - Distinctive wing skeleton formed by elongation of fingers - thin leathery patagium forms between digits - reduced hind limbs - large ears.
*Order Artiodactyla
Even-toed ungulates - Pigs, Hippos, Camels, Deer, Giraffe, Antelopes and Cattle (~280 spp.) Named for bearing their body weight on the third and fourth toes, artiodactyls are primarily herbivorous and are distributed worldwide. Many members of the clade possess head ornamentation. Look for - most with complete post orbital bar (orbit separated from temporal fenestra) - most with large diastema - many with head ornamentation in the form of antlers, pronghorns, true horns and ossicones - reduced upper incisors - Sexual dimorphism is common in artiodactyls.
Order Pholidota -
Pangolins (8 spp.) Restricted to Southeast Asia and Africa, pangolins are also called scaly anteaters. Look for - Body entirely covered in epidermal scales - toothless elongate snout - large claws for digging - arboreal forms with prehensile tails.
What are eutherians commonly referred to as?
Placental mammal - though a placenta is present for part of the development of marsupial mammals as well.
Order Afrosoricida
Tenrecs and Golden Moles (~40 spp.) The golden mole (we have no tenrec material) is convergent with true moles in having a suite of adaptations related to their fossorial lifestyle. Look for - smooth shiny pelage - reduced eyes and ears - large broad claws - short limbs - short tail.
Sweat Glands
aid in thermoregulation through transpiration of water from the skin surface
Vibrissae
also known as whiskers, vibrissae are long stiff hairs with highly innervated bases and serve a tactile sensory function. They are arranged in clusters typically located near the nose/mouth, eyes and legs.
Metatherians
are commonly referred to as marsupials, so named for the presence of a pouch (marsupium) used to house offspring during development outside the womb.
Order Perissodactyla
odd-toed ungulates: horses, rhinos, tapirs
