integument & locomotion

integument structure and function

• interface between a mammal and its external environment

• protect cells and tissues from environment

• conserve water

• conserve heat (insulation) or dump it

• communication

• secondary sexual character

integument structure/function: skin - 3 layers

1.) epidermis: outer layer of dead keratinized cells that prevents desiccation of underlying skin

2.) dermis: contains connective tissue, blood vessels, nerves, and integumentary muscle

3.) subcutanenous layer (hypodermis): loose connective and adipose (fat) tissues, some of which serve as insulation or energy reserves

sebaceous glands

• derived form epidermis

• associated with hair follicles

• secrete an oil product called sebum that keep hair shaft moist and waterproof

• lanolin cream is from sheep sebaceous glands

eccrine glands

• lie deep in dermis layer; not associated with hairs

• produce sweat that helps cool through evaporation

• all over the body in primates; hairless areas in non-primates

apocrine glands

• derived from epidermis

• produce viscous fluids that act as chemical signals (pheromones)

• in primates: restricted to armpits, anogenitcal region, nipples; in nonprimates: all over body

scent glands

• modified sebaceous or apocrine glands

• used as pheromones (chemical signals used for communication)

• used to deter predators, mark territories, or mark sites for spatial orientation

mammary glands

• functional only in females but dayak fruit bat (Dyacopterus spadiceus) is exception

• ducts extend through elevated nipple or teat

• number and location and glands vary

mammary glands in prototherians

• simple aggregations of glandular tissue along abdominal wall

• have neither nipples nor teats

• milk secreted into depressions and licked off fur by young

which glands produce chemicals signals?

apocrine

arrector pili

a tiny smooth muscle at the base of each hair within the dermis; cause hairs to stand erect when muscles contract

hair classifications (7)

1.) angora - grows continuously to produce long shafts which may or may not be shed (like in horses)

2.) definitive hairs - grows to a fixed length and then falls out (like in dog coat)

3.) vibrissae - long, stiff hairs that function as tactile receptors and exhibit definitive growth (whiskers)

4.) guard hairs - longer, often course, which complement underfur (short, fine, and dense)

5.) spines - stiff and enlarged guard hairs (like in porcupines)

6.) bristles - form long hairs often for visual signals (like in lion’s mane)

7.) wool - long, soft, and usually curly

functions of hair (5)

• insulation - dense underfu; piloerection

• protection from UV, abrasions, etc.

• sensory - sense immediate surroundings, like through vibrissae or whiskers

• communication - interact with immediate surroundings

• secondary sexual character - supporting male/male competition and female choice

crypsis

color of animal matches that of the substrate; (basically camouflage?)

hair pigment (or lack of)

• pheomelanin - shades of red or yellow

• eumelanin - shades of black or brown

  • albinism - when melanin production is blocked

  • leucism - loss of pigmentation (but does not affect eyes)

  • melanism - opposiite of albinism, much darker color

kerantinized structures on digits (3)

• claws: most primitive form; consist of unguis (hard exterior) and subunguis (softer ventral surface); used for climbing, digging, fighting, defending

• nails: covers only the dorsal surface of phalanx; gripping and object manipulation

• hooves: ungulates; U or V shaped ungis; forms sole of foot

true horns

• found only in bovids

• inner core of dermal bone

• covered by a keratinized sheath

• grow continuously throughout life

• remain unbranched and never shed

pronghorn

• found in Antilocapridae

• keratinized sheath shed annually; bony core persists

• two branched horns

• sexual dimorphism (smaller in female)

antlers

• found in cervids

• branched head ornaments made entirely of bone

• covered by layer of velvet (highly vascularized skin)

ossicones

• ossified cartilage

• extension over the parietals

• covered in skin and fur

hair horn

• no bony core or keratinized sheath

• found in family rhinocerotidae

adaptive significance of hood ornaments

• male-to-male competition

• female choice (size of antlers shows male quality)

• defense

four functional requirements

1.) support and stability even through the feet make only intermittent contact with the substrate

2.) propulsion to move the body forward

3.) maneuverability

4.) endurance

foot positions (4)

• plantigrade: foot posture in humans, bears, opossum; all or most of the palms and soles are in contact with substrate

• digitigrade: foot posture in dogs, cats; elevated metacarpals and metatarsals to acute angle (only on phalanges)

• unguligrade: ungulates foot position; only tips of phalanges (horses)

• graviportal: columnar legs in heavy species (e.g., elephants)

name posture and associated gaits

plantigrade - walking (ambulatory) and scurrying (scampering); e.g. squirrels

name posture and associated gates

digitigrade (dog) and unguligrade (deer) - running (cursorial)

saltatorial locomotion

jumping and richocheting - jumping uses all four limbs; richocheting is done bipedally

adaptations for saltatorial locomotion

• long hindlimbs

• fused metatarsals called cannon bone

• tibia and fibula fused into tibiofibula

• heavy and elongated tail

• long elastic tendons for storing jumping energy

• lumbar vertebrae robust; cervical vertebrae often fused

adaptations for climbing locomotion

• long limbs with slender bones

• very long forelimbs and enlarged feet

• opposable pollex or hallux

• long and deeply curved claws

• prehensile tail

scratch diggers

• soil is loosened with foreclaws and flung to rear with hind or forefeet

• developed claws and long olecranon process

chisel tooth diggers

• huge, gnawing incisors

• powerful jaw and neck muscles used to dislodge soil

rotation thrust diggers

• “swimming” motion of broad, shovel-shaped forefeet

• short, powerful forelimbs

adaptations for digging and burrowing

• tubular, heavy body shape with reduced neck

• reduced or lost eyes and pinna

• limbs short, thick, powerful

• curved digging claws (in scratch diggers)

• broad, shovel-like claws

• tailed reduced or nearly absent

• very procumbent upper and lower incisors (in chisel tooth diggers)

what are the main types of diggers

chisel, scratch, and rotation

adaptations for flying

• gliding (glissant) and flying (volant)

• patagium-extensions of skin from wrist to ankles

adaptations for swimmers

• dense fur for insulation and buoyancy

• elongated body

• ear and nostril openings reduced

• tail modified

• webbed phalanges

• bristles on lateral surface or plantar surface