Chordates Part II Flashcards
aquatic mammals minimum body size
much larger than terrestrial
set by thermoregulatory demands of aquatic environment
larger mass animal bones
allometric growth
larger bones to support the weight, larger diameter, more robust
SA:V changes
as size increase, SA:V decreases
1unit cube = 6:1
2unit cube = 12:8 (1.5)
smaller ratio = lower rate of heat loss
sphere SA:V
SA = 4πr^2
V = (4/3)πr^3
smaller SA:V than cube of equal volume
minimize ratio for given volume
SA:V changes with shape
slender objects higher SA:V
ectotherms- lower MR, small, long, slender
consequences of size and shape variation
allometric relationships
eggs per female increase with body weight
influences survivorship and reproduction
evo devo
evolution and development
gene duplication
single genes
segment of chromosome
whole chromosome
whole genome
pseudogene
DNA sequences similar to normal genes but non-functional; as defunct relatives of functional genes
sub-functionalization
pairs of genes that originate from duplication, or paralogs, take on separate functions; ancestral gene-2 functions, new gene- 1 function
duplication events result in
pseudogenation
sub-functionalization
neo-functionalization
neofunctionalization
one gene copy, or paralog, takes on a totally new function after a gene duplication event; adaptive mutation process; one of the gene copies must mutate to develop a new function
functional divergence
genes, after gene duplication, shift in function from an ancestral function
gene duplications =
bursts of diversification
gene duplication, vertebrate evolution
3 episode widespread gene(ome) duplication
origin of verts, gnathostomes, teleosts
HOX clusters
4 in vertebrates
7-8 in teleost
snake venom toxins
co-opted from pancreatic origin
expanded by gene duplication
evolved under positive selection- neo-functionalization
Coqui development
no tadpole stage
rearrangment of development program
tail resorbed before hatching
adult characters (limbs) develop directly
frog with no direct development
tail growth before limb growth- gas exchange surface
classic neo-Darwinian 3-stage view of origin of species
mutation- new variant
selection- altered frequency/fixation (‘new population’)
reproductive isolation- new species
altered 4-stage evolved view of origin of species
mutation– new gene
re-programming- new ontogeny/individual
selection– new population
reproductive isolation– new species
re-programming
developmental/embryonic/ontogenic reprogramming or repatterning
mechanisms of developmental reprogramming
changes in developmental programs at various stages of life heterotopy heterochrony heterometry heterotypy
heterotopy
∆ location of gene expression
heterochrony
∆ timing of ≥2 processes relative to each other
- onset, offset, rate of process
- must be allometric
heterometry
∆ amount of gene product
heterotypy
∆ kind of gene product
transformation grid
1 species = reference
reference points relocated in derived species to reconstruct transformed grid
heterochronic change
∆ rate of development to maturity
∆ time to maturity
∆ time of onset of development
alone or combined, same or different times
classic neotony
axolotl- retains larval features (gills, fins)
neotony
paedomorphosis, retention of ontogenetic features into adulthood
heterochronic process graphs
∆ timing of development
a- ancestral, d- descendant, k- rate of shape development, a- rate of onset of growth, ß- age when offset shape is attained
paedomorphosis- development is truncated
deceleration
hyomorphosis
postdisplacement
paedomorphosis, deceleration
neotony
(-k): smaller slope, lower shape change in same time of development
paedomorphosis, hypomorphosis
(negative offset, progenesis)
same slope, shorter time period = smaller change in shape
paedomorphosis, postdisplacement
(positive onset)
onset of growth is later, offset is same, smaller change in shape
peramorphosis- development is extended
acceleration
hypermorphosis
predisplacement
peramorphosis, acceleration
(+k), steeper slope, faster change in shape over same time period, larger change in shape overall
peramorphosis, hypermorphosis
(positive offset)
start time same, end time later, longer period of development = greater change in shape
peramorphosis, predisplacement
(negative onset)
start time is earlier, end time is same, longer period of development = greater change in shape
shorter development time to maturity
miniaturization
either ∆ time to maturity or ∆ time of onset
∆ time to maturity
progenesis
∆ rate of development to maturity
neoteny
facultative paedomorphosis
environmentally induced polymorphism, results in coexistence of mature, gilled, fully aquatic paedomorphic adults and transformed, terrestrial, metamorphic adults in same population
really phenotypic plasticity
peramorphosis
individuals of a species mature past adulthood and take on hitherto unseen traits. It is the reverse of paedomorphosis
paedotypy
‘paedomorphosis’ but within a population- sometimes the organisms exhibit the change sometimes they do not
paedomorphosis in relation to paedotypy
comparison between species
descendents exhibit the change, ancestors do not
local heterochrony
changes in specific parts of body (animals are mosaics of different characters)
local terms- paedotypic somatic develop., per atypic gonadal develop.
why exhibit paedomorphosis
often determined by environment
saves energy of metamorphosis
early maturity
early reproductive output
amniote heart development
earlier development in all amniotes, not originally for endothermy, may be due to nature of egg– yolk movement, gas exchange
Tarsier
largest eye:body mass of all mammals
smaller than diapsids at initial devel.- allometric heterochrony
diapsid
(“two arches”) amniote tetrapods that developed two holes (temporal fenestra) in each side of their skulls
bird heterochrony
birds are miniature dinosaurs- pedomorphosis?
front limb:back limb larger in birds
birds have longer front limb relative to back limb
positive allometry of front limb
skull shape consistent w/ juvenile dino.
bird relaxed selection of front limbs
allowed them to ‘experiment’ with limb length- feeding?
led to wing development- exaptation
bird skulls
suggest pedomorphosis
retain juvenile shape overall and in bill, unlike dinosaur, alligator
bird mosaicism
peramorphic- bill, front limbs
paedomorphic- skull, back limb
ratites
ostrich, paedomorphic wing, skull; peramorphic hind limb, more robust skull
mosaic
mosaic animals
can’t say an animal is paedomorphic, must be more specific
giant anteater
very long snout, peramorphosis, allometric growth
bovid, kudu
very elaborate horns with large skull size
peramorphosis, allometric growth
peramorphosis in certopsian dinosaurs
bigger animal = larger differentiation from juvenile form
Hawaiin honeycreepers
peramorphosis in none, one, or both bills
human paedomorphosis
paedomorphic apes?
retention of younger developmental stages of apes
differential heterochrony between sexes
sexual dimorphism
blue boxfish: adult female is paedo. compared w/ male in body shape and color pattern
male anglerfish
salamander heterochrony
ovoviparous, viviparous
feeding much earlier in viviparous form
vivipary
development of the embryo inside the body of the mother
live birth
oviparous
animals that lay eggs, with little or no other development within the mother
ovoviparous
develop within eggs that remain within the mother’s body up until they hatch or are about to hatch
developmental trajectory
gradual, slow ontogeny or steps may be condensed for quicker ontogeny into fewer steps, then if one step is skipped you see bigger changes
salamander foot
B. occidentalis toes stop growing early, growth curve levels off, toes never project far out of pad— webbed foot, suction cup
timing of migration of neural crest cells
alters features, skin color
salamander- white = delayed crest cell migration- no color developed
color derivatives of neural crest cells
iridophores (blue?)
xanthophores (yellow)
erythrophores (orange)
melanocyte (black)
organ system
set of organs interacting to carry out major body functions
organ
body structure that integrates different tissues and carries out a specific function
vertebrate support/locomotion organ systems
skeleto-muscular system
vertebrate metabolism organ systems
respiratory system
digestive system
excretory system
vertebrae transport organ system
circulatory system
vertebrate reproduction organ system
reproductive system
vertebrate integration organ system
neuro-endocrine system (nervous system, endocrine glands)
vertebrate support and interaction organ
skin
homeostasis
maintaining stability, negative feedback
homeostasis feedback
environment ∆– physiological ∆– ∆ detected by neural receptors– info. sent along sensory pathway– integrator cells receive info. – info. sent along motor pathway– compensatory changes made by effector(s)– conditions returned to desirable levels
temperature regulation feedback
∆ detected by skin, hypothalamus– info. sent along afferent (sensory) pathway– neutrons receive sensory info. (brain)– info. sent along efferent (motor) pathway– actions
overall feedback model
increase/decrease– receptor (sensor)– integrator– effector(s)
nervous system main organs
brain, spinal cord, peripheral nerves, sensory orans, coordinates homeostasis
nervous systems present
in all metazoans except sponges
endocrine system organs
pituitary, thyroid, adrenal, pancreas, hormone-secreting glands
muscular system organs
skeletal, cardiac, smooth muscle- thermoregulation
skeletal system organs
bones, tendons, ligaments, cartilage
integumentary system organs
skin, sweat glands, hair, nails; skin largest organ, multiple functions
circulatory system organs
heart, blood vessels, blood; interacts w/ everything
lymphatic system
lymph nodes, lymph ducts, spleen, thymus
respiratory system organs
lungs, diaphragm, trachea, airways
digestive system organs
pharynx, esophagus, stomach, intestines, liver, pancreas, rectum, anus
excretory system organs
kidneys, bladder, ureter, urethra
reproductive system organs
ovaries, oviducts, uterus, vagina, mammary glands, testes, sperm ducts, accessory glands, penis
vertebrate coelom cavities
most have 2; pericardial (surrounding heart), pleura-peritoneal
mammals also have 2 pleural cavities (lungs)
coelom organs
organs are connected to cavity to be held in place
some organs outside of cavity (kidneys)
useless parts
vestigial, ‘hold overs’, ancestry
some human vestigial parts
third eyelid, darwin’s point, wisdom teeth, erector pili, body hair, coccyx, neck rib, thirteenth rib, fifth toe, paranasal sinuses, vomeronasal organ, fellowmen reflex, extrinsic ear muscles, subclavius muscle, palmaris muscle, plantaris muscle, pyramidalis muscle, appendix, male nipples, male uterus
third eyelid
Nictitating membrane- protects eye and sweep out debris, snow blindness, in birds, fish, amphibians, reptiles, tiny fold in inner corner of human eye
Darwin’s point
small, folded point of skin at top of ear in modern humans, remnant of larger shape to focus distant sound
wisdom teeth
early humans chewed lots of plants- another row of molars useful, only ~5% of population has a healthy set of 3rd molars
erector pili
smooth muscle fibres allow animals (mammals) to puff up fur to insulate or intimidate
- humans- goosebumps
- dogs/cats- fur standing up
body hair
brows- keep sweat out of eyes
male facial hair- sexual selection
most human body hair has no function
coccyx
fused vertebrae all that is left of tail
tail lost before humans began walking upright
neck rib
set of cervical ribs, leftovers from age of reptiles?, appear in <1% of population, cause nerve/artery problems, also associated w/ childhood cancer?
thirteenth rib
8% of adults have 13, most of us have 12
left over from chimps, gorillas?
fifth toe
mainly for balance in humans, grasping clinging to branches in apes
paranasal sinuses
nasal sinuses of ancestors may have been lined w/ odour receptors– heightened smell, aid survival
now- troublesome mucus-lined cavities, moistens air we breathe, makes head lighter
vomeronasal organ (VNO)
tiny pit on each side of nasal septum filled w/ nonfunctioning chemoreceptors
maybe once a pheromone detecting ability?
flehmen reflex
exposes VNO just behind front teeth (like horses)
expose to air, where pheromones are expected to be present
extrinsic ear muscles
trio of muscles, made it possible for pre hominids to move ears independently of heads
we still have them– ppl can wiggle ears
subclavius muscle
under shoulder from 1st rib to collarbone, useful for walking on all four
people have 0-2
palmaris muscle
long, narrow, runs from elbow to wrist, missing in 11% of humans, may have been for hanging, climbing
used for reconstructive surgery
plantaris
often mistaken for a nerve
useful for primate grasping with feet
not present in 9% of humans
pyramidalis
tiny, triangular, pouch like muscle, attached to pubic bone- from pouched marsupials?
>20% of humans don’t have
appendix
narrow, muscular tube, attached to large intestine for digesting cellulose when humans ate more plant matter, produces some white blood cells
>300,000 Americans/yr get it removed
male nipples
lactiferous ducts from well before testosterone causes sex differentiation in fetus
men have mammary tissue that can be stimulated to produce milk
male uterus
remnant of undeveloped female reproductive organ
hangs off male prostate gland
integument skin
injury, microbial, predator protection regulation of water regulation of Tb social interactions excretion/elimination of waste respiratory gas exchange muscle attachment sensory wrapping- shape and support
integument water regulation
water can pass both ways but amount that can pass varies in different animals- amphibians drink through skin
integument Tb regulation
hair, feathers, blood supply in skin, coloring
integument social interactions
color, size of feathers, chemical attractants from glands
skin characteristics
heaviest organ in body
most functions
remarkable repair functions
interface w/ environment, serious damage = serious problems
integument made up of
dermis and epidermis
dermis
lower layer
thick, protective functions
consists of layers
dermis made up of
stratum spongiosum stratum compactum hypodermis exoskeleton dermal plates/scales bone dentin(e), enamel chromatophores
stratum spongiosum
most of blood vessels that feed other layers of skin
stratum compactum
more compact layer below spongiosum
hypodermis
covering of muscles, fat deposits, muscles that allow skin to move relative to rest of body
dermis characteristics
collagenous and elastic fibres, fibroblasts, bones, scales, nerve fibres, blood vessels, smooth muscle, mesodermal
exoskeleton
reptiles, turtles, crocodiles
enamel
hydroxyapatite
less fibrous, harder (than bone or dentin)
fossil agnathans
ostracoderms
elaborate bony armour
derivatives of primitive dermal bone
lamellar bone
spongy bone
dentin
enamel
denticle
dentin + enamel
placoid shark scale
lamellar bone + dentin + enamel
kinds of bone
dermal/membane bone
endochondral bone
dermal bone
formed in membranes
intramembranous ossification
exoskeleton, dematocranium
endochondral bone
formed in cartilage
endochondral ossification
endoskeleton
chromatophores
dermis produced color, stellate, cells and pigment granules within move around
melanophores
liphophores
iridophores
stellate
neurons with several dendrites radiating from the cell body giving them a star shape
melanophores
contain melanin (dark pigment)
excess melanin
melanistic = black
lack of melanin
albinistic - very conspicuous, low survival
liphophores
contain corotanoids
xanthophores (yellow), erythrophores (red)
fossil dermis findings
skin pigments in extinct animals, convergence of melanism
ToF-SIMS to detect melanin
time-of-flight secondary mass spectrometry
composition & spatial distribution of surface molecules, including comparisons w/ spectra of melanin
SEM to detect melanin
scanning electron microscopy
presence of ovoid bodies consistent w/ melanophores
EDX to detect melanin
energy-dispersive x-ray microanlysis
carbon associated w/ skin and not adjacent sediment
evidence of melanism in 3 extinct animals
3 marine reptiles, each lineage secondarily aquatic
Ichtyopterygia, Mosasauroidea (Squamata), Eosphargis (Testudines, turtle?)
melanin function
thermoregulations- especially in turtle?
crypsis- ichthyosaur lacks countershading (deep diving habit, background matching in low light)
iridophores
contain crystal plates made of guanine- reflect light, influence perceived color
cyanophore
blue pigment, very rare, only known in a few species of fish
color changing
position of chromatophore
∆ distribution of pigment granules w/i chromatophore
seasonal moult
shifts in relative position of chromatophores
chromatophores- ameoboid
ex. if yellow pigments move onto of black pigments
distribution of pigment granules within chromatophore
densely packed or dispersed- density of color
seasonal moult
of plumage (birds) or pelage (mammals) color in epidermal structures can be 'dropped'
chameleons color changing
interactions- agressive, courting
antipredator response
dominant individual use color as social signal
sexual dichromatism
sexual dimorphism
greater in breeding season than rest of year- spend energy to enhance breeding color
seasonal color change
camouflage, varies geographically, may be shown some places and not others, background matching, moult btw color change
seasonal color change examples
Arctic Hare (Lepus arcticus) Rock Ptarmigan (Lagopus muta)
ontogenetic color change
color change through life, younger animals generally more vulnerable
ontogenetic change examples
mule deer- baby spotted, camouflage when laying down
Racer- snake, adults plain blue/grey, blotches on young
structural color
physical properties of body colouring
especially dramatic in birds
feathers refract light in various ways- differences in angle we look at it
blue amphibians
rare, usually not due to pigment, light is scattered by iridophores
chromatophore layers
filtering layer (xanthophore), scattering layer (iridophore), absorbing layer (melanophore) short λ (blue-green) largely absorbed by filter. med λ (yellow-green) pass through filter.- scattered by scattering layer- back through filter long λ (red-orange) - pass through filtering and scattering, absorbed by absorbing layer
parts of epidermis
stratum corneum
stratum germinativum
derivatives
stratum corneum
outer layer, shed old cells in flakes or one piece
stratum germinativum
below corneum, source of new cells which move up to outer layer
epidermis derivatives
various function glands keratinized structures (nails, claws, hooves, scales/scutes, hair, feathers, horns, antlers, foot pads, beaks)
glands
are IN dermis
BUT epidermal in origin
hair
dips down into dermis BUT epidermal derivative
keratin/lipids
barriers to water loss and UV
amounts of keratin are variable among taxa
mucus glands
moisture, gas exchange, cooling
granular glands
produce defence toxins
epidermal glands
mucous, poison, scent, sweat, sebaeous, mammary, uropygial
sebaceous gland
base of hair, lubricant for skin
uropygial glands
base of tail in birds, preening feathers, produces oil
mammarly glands
nipple- many ducts
teat- single duct
fish scales
bony scales, dermal, permanent, not shed, only lost through injury, persist throughout life, new growth every year
reptile scale
horny scales, epidermal, shed, called scutes
claw, beak, horn structure
central bony core, covered by vascularized dermis, outer epithelial layer
hair
keratonous, not modified scales, novel, grow from bone throughout life, multiple kinds (fine coat, second coat (guard hairs) grow through to provide protection)
feathers
down- close to body, small feathers, insulation
body contour feathers- grow through
flight feathers- moulted periodically and replaced, occur in tracks along body
skin as a sensory organ
touch receptors, transmitting pain, temperature, itch, touch information to CNS
important interface between body and environment
skin receptors
nociceptors, pruriceptors, thermoreceptors, mechanoreceptor, hair/glabrous skin, lips/tongue/cheeks, mystical pads, tactile foraging
nociceptors
pain
pruriceptor
itch
hair/glabrous skin reception
glabbrous/nebrous skin- free of hair (palms, soles)
discriminative touch- clearly distinguish differences in objects, descriminate more clearly
lips/tongue/inner cheeks reception
localization and movement of food
mystacial pads, vibrissae
snout of animals, long whiskers
vibrotactility, navigation, spatial orientation in dark
extend sensitivity beyond skin surface
tactile foraging
snout of star nose mole
elaborate w/ tentacles extremely sensitive to touch, finds way around and food
fish sounds
> 700 known vocal species
fish sounds
simple vs complex
same frequency, varying frequency/amplitude (moans, growls, peals)
how do fish make sounds
stridulation
air passage
drumming
stridulation (fish sounds)
rubbing/scraping together fins, bones, teeth
air passage (fish sounds)
little understood, internal movement of air, escape of air through mouth, gills, anus (farts), FRT- frequently repetitive ticks
waveform
amplitude vs. times
spectrogram
frequency (kHz) vs. time (s)
types of FRTs
3 types- FRT1, FRT2, FRT4
~2-8kHz, ~50-60dB, differ in amplitude
drumming (fish sounds)
‘sonic’ muscles pushing/pulling on internal air/swim bladder
males have longer muscles than females
why/when fish are vocal
spawning, courtship, agression, territorial, distress, predator/prey behaviour
cod drumming muscles
larger in males
larger at spawning time
correlated with fertilization potential
haddock courtship behaviour
pulse repetition rate changes at each stage of courtship- increases in frequency
studying fish sounds
passive acoustics
technology
passive acoustics
simply listening to sounds w/ hydrophones
non-invasive, non-visual (light not needed), continuous remote monitoring, provides detailed behaviour info
technology (fish sounds)
AULS
ROVs
Autonomous glider
AULS
autonomous underwater listening stations
ROVs
remotely operated vehicle
autonomous glider
buoyancy-drive AUV
moves through water independently, no engine, moves via density changes
ecological uses of fish sounds
locate vocal fishes
determine when fish are vocal
study of underwater noise effects
examine fish interactions
locating vocal fishes
identify essential fish habitat (EFH)
locate spawning habitats
exploration of the seas
census of marine life
determining when fish are vocal- season and time of day
spawning behaviour
predator/prey interaction
foraging
territorial defense
studying underwater noise effects
identify noise sources and levels
quantify temporal/spatial patterns in noise
quantify noise impact on fish behaviour
cusk-eel
found in Cape Cod by low tech passive acoustic methods, call in chorus just after sunset, tracks time of sunset through summer,
Haddock
using AULS 1000m deep, first in situ recordings in NA, recorded daily vocal activities- more vocal late in day, spawn mostly at night-
freshwater drum in hudson river
widely distributed highly vocal family, invasive, may spawn within canals that drain into Hudson
how did FW drum make it to hudson river
track acoustic path, with emphasis on spawning locations
found drum sounds in lake champlain canal, expected to spread dramatically and may alter rivers ecosystem
NEPTUNE canada subsea instruments
Hydrophones, seismometer, piezometer, bottom pressure recorder, gravimeter
piezometer
measure liquid pressure
gravimeter
measure local gravitational field
penetrometers
moisture, strength, harness of substrate
VENUS
Strait of Georgia, Saanich Inlet
UVic data archive, shore station, instrument platforms, nodes, autonomous vehicles, surface monitoring by BC ferries, satellites, gliders, profiling system
noisy ocean
peak listening is 1-10kHz (low frequency), lots of anthropogenic noise
fish hearing
fish have 2 inner ears, no middle or external ear, inner ear similar to other verts., sensory hair cells responsible for converting sound to electrical signal
potential effects on hearing
high intensity (transient)- fatigue, damage or kill sensory hair cells low intensity (shipping)- may have behavioural and physiological consequences
fish sensory cells
can be replace or repaired, unlike mammals
pile driving noise
direct mortality in surfperches
startle and alarm responses when exposed to air gun- rockfish, tighter school, school collapse, become motionless
behavioural effects of noise
distribution
fitness- reduced growth, reprod.
predator-prey interaction- interference
communication- range reduction, info loss
shipping noise
most extensive source of noise in ocean, especially along major shipping channels
reproductive consequences
physiological stress, restricting mate finding, keeping fish from preferred spawn sites
masking communicative sounds
impact ability of fish to communicate acoustically or use acoustic ‘soundscape’ to learn about envrionment
masking predator-prey relationships
affect ability to find prey or detect presence of predators
skeletomuscular system
vertebrate characteristic
internal, jointed skeleton (bone or cartilage)
works with muscular system
skeletomuscular functions
support of body movement via joints enclosure/protection of vital organs storage of minerals assistance in lung ventilation (amniotes)
skeletomuscular body support
ligaments, tendons, muscles
skeletomuscular mineral storage
Cap, P, Mg in bones
skeltomuscular lung ventilation
muscles connected to ribs
important connective tissues
cartilage bone ligaments tendons muscle
cartilage
matrix collagen chondroblasts chondrocytes lacuna(e)
chondrocytes
only cells found in healthy cartilage; produce and maintain cartilaginous matrix
chondroblasts
make cartilage matrix
lacuna(e)
hole in which cells grow
cartilage characteristics
more flexible than bone
most skeletons start w/ cartilage
offer support, bone growth
no blood vessels
types of cartilage
Hyaline
Fibrocartilage
Elastic
Hyaline cartilage
‘temporary’ cartilage during growth; most articulations, ribs, nose, larynx; least elastic; low collagen
Fibrocartilage
intervertebral disks, other joints (meniscus in knee); load bearing; show absorption; joint stabilization; able to resist pressure w/ minimum friction; moderately elastic; moderate collagen
Elastic cartilage
pinna, epiglottis, other parts of visceral skeleton; vibrational properties help emit/receive sound; most elastic; most collagen
knee minisci
important for knew function- load bearing, shock absorption, joint stabilization, joint lubrication, proprioception
proprioception
ability to sense stimuli arising within the body regarding position, motion, and equilibrium
bone properties
support and locomotion organic components mineral components mineral reserves dynamic
bone support and locomotion
balance between stiffness (hardness) and toughness (strength)
bone organic components
ex. collagen
toughness and elasticity
resistance to tensile loads
bone mineral components
ex. hydroxyapatite
stiffness, resistance to compressive loads
bone mineral reserves
Ca, P, Mg
bones, dynamic
modeling and remodelling
reabsorption and deposition
bone parts
osteoblast, osteocyte, osteoclast lacunae, canaliculi compact, spongy marrow woven, lamellar periosteum
osteoblasts
cells with single nuclei that synthesize bone
osteocytes
star-shaped cell, is the most commonly found cell in mature bone
osteoclasts
type of bone cell that resorbs bone tissue. This function is critical in the maintenance and repair, and remodelling of bones
bone lacunae and canaliculi
small canals between cells, blood cells and transport materials
periosteum
protective sheath around bones that connects to blood vessels and other structures like tendons
osteon
fundamental functional unit of much compact bone; bundle of blood vessels and lacunae
two types of tissue that form bone
compact
spongy
compact bone
cortical; facilitates bone’s main functions: to support the whole body, protect organs, provide levers for movement, store/release calcium; forms the cortex (outer shell) of most bones
spongy bone
cancellous, trabecular bone; higher SA:mass; less dense; softer, weaker, more flexible; suitable for metabolic activity-exchanges Ca; typically found at ends of long bones- proximal to joints, within interior of vertebrae; highly vascular; frequently contains red bone marrow- hematopoiesis
marrow
flexible tissue in interior of bones, 2 types yellow: fat red: blood cells birth- all red adult- 1/2 red
hematopoiesis
production of blood cells
woven bone
no uniform structure; early development; eventually replaced by lamellar bone
lamellar bone
compact, spongy, vascular canals, osteons, ‘plywood’ structure
plywood structure
regular parallel alignment of collagen into sheets (lamellae), mechanically strong, much lower proportion of osteocytes to surrounding tissue
bone stiffness
trade-off with toughness
high T low S: collagen– wood– chitin– bone– tooth dentin– mollusk shell– tooth enamel– glass, concrete, rocks, pottery
strain
dimensionless, epsilon = ∆length/length
stress vs. strain plot
elastic region– yield point– plastic region- fracture point
elastic region (stress vs. strain)
increases with high slope
rubber band like
steeper slope = less elastic
plastic region (stress vs. strain)
much lower slope increasing
stays together but is deformed
fracture point (stress vs. strain)
material breaks
stress
sigma = F/A
tissue stiffness =
y / x (stress/strain)
>yield pt. - yield or failure
bone elasticity
- 007% of strain
- 003 normal strain
- 015 results in fracture
ossification involves
direct or indirect
heterotropic bones
membranous ossification
direct laying down of bone- dermal armour, dermatocranium, parts of visceral skeleton, clavicle, others
endochondral ossification
indirect, cartilage precursor- most of axial and appendicular skeleton
ossification
laying down new bone material by osteoblasts- bone tissue formation
Heterotopic bones
isolated bones formed outside skeleton proper
sesamoid bones
small bones associated w/ tendons, joints; Often form in response to strain; act like pulleys, prove smooth surface for tendons to slide over increasing muscular forces
long bone structure
epiphysis, metaphysis, diaphysis
epiphysis
rounded end of a long bone, at its joint with adjacent bone(s)
diaphysis
the long midsection of the long bone
curious heterotopic bones
baculum, baubellum
Os penis, os clitoridis
baculum
penis bone, penile bone or os penis; bone found in the penis of many placental mammals, absent in human, function unknown- lock and key? some have projections, trident
baubellum
os clitoridis – a bone in the clitoris
bird bones
light skeleton, not necessarily light bones, hollow bones- air filled, not marrow filled; very dense bones, especially cranial compared w/ other animals
pneumaticity
air spaces in bones
post cranial pneumaticity
only birds, dinosaurs, perhaps gas exchange system
bone density
proportional to bone stiffness and strength
dense bone
stiffer, stronger, heavier
bone density vs. shape graph
heavy-light density vs. less-more rigid shape
min. density and rigidity = low stiffness and strength
max density and rigidity = high stiff. and strength
isoclines of stiffness and strength
medullary bone
woven bone, female birds, formed seasonally, prior to and during egg-laying, Ca reservoir for building hard eggshell
3 kinds of eggshells
hard
flexible
soft
hard shell
self-contained, rigid, fossils
calcareous matter dominates; tortoise, bird, dino, croc, gecko
flexible shell
needs water, calcareous layer loose, some fossils; turtles
soft shell
needs water, organic matter dominates, no fossils, gecko, tuatara, lizard, snake
crocodilian egg laying
pre-ovulatory hpercalcemia (takes 40% of Ca to make eggshells), no medullary bone formed
medullary bone significance
underscores evolutionary link btw. bird and dino
similar reproductive bio
means of sex ID in dino
ligaments
hold bones together, provide support, connective tissue, typically collagen
patellar ligament
between patella and tibia
holds tibia and femur together
2 main skeleton classifications
endoskeleton, exoskeleton
OR cranial, postcranial
exoskeleton
within integument
keratinized exo. - epidermis
bony exo. - dermis
endoskeleton
deep, within body
bony endo.
cartilagenous endo.
notochord
cranial skeleton
splanchnocranium
chondrocranium (cartilage)
dermatocranium
postranial skeleton
axial skeleton
appendicular skeleton
axial skeleton
vertebral column
notochord
appendicular skeleton
limbs
girdle
endoskeleton cartilage bone
vertebrae, ribs, limb bones
endoskeleton membrane bone
centra (teleost), sesamoid
exoskeleton dermal bone
skull roof, dentary, clavicle, gastrula, fish scales, osteoderm
gastralia
dermal bones found in ventral body wall of crocodilian/Sphenodon, between sternum and pelvis, do not articulate with vertebrae, support for abdomen, attachment sites for abdominal muscles
sphenodon
tuatara
main components of the skeleton
dermal
endoskeleton: somatic (axial, appendicular), visceral
median fin
median fin
one of the unpaired (i.e. dorsal, anal, and caudal) fins, restricted to fish, stability, propulsion
nuchal ligament
supports head, keeps it upright
degree of exoskeleton
greatly varies in all taxa
origin of vertebrate head skeleton
deep homology and co-option (exaptation)
spread of tissue through head (neural crest), not evolution of new skeletal tissue
axial skeleton
braincase, vertebral column, ribs
braincase
endochondral part of skull
vertebral column
backbone, tail, articulating vertebrae
first vertebra
atlas- allows up and down motion of head
atlas articulates with
occipital condyle(s) on back of braincase
second vertebra in amniotes
axis- allows rotary motion of head
parts of vertebra
centrum, neural arch and spine, zygapophyses (pre and post), diapophyses
occipital condyles
1 or 2 in tetrapods
undersurface protuberances of the occipital bone, articulates w/ superior facets of the atlas vertebra
centrum
main body of vertebra
neural arch
above centrum, spinal cord runs through
zygapophyses
projections of the vertebra that fit with adjacent vertebra; articulation, lateral/up/down motion, resist portion
diapophyses
the part of the transverse process of a thoracic vertebra that articulates with its corresponding rib
vertebrate lateral motion
many vert., including tetrapods, use lateral motion for locomotion, mammals- minimally
fish vertebral column
less flexible, without zygapophysis
dimetrodon
elaborate extension of neural spines, probably supported sail, evidence of vascularized tissue- thermoregulation, and/or social signalling
regionalizations of vertebral column
Trunk- Presacral, Cervical, Dorsal, Sacral
Caudal
Dorsal vertebra
thoracic, lumbar
frog vertebral column
very short, don’t bend well, highly reduced
mammal cervical vertebrae
7, typically do not have ribs
mammal ribs
thoracic vertebrae
mammal caudal vertebrae
tail, coccyx
urostyle
long bone-fused vertebrae at base of vertebral column, frogs and toads
bird vertebral column
stiff, lots of fusion, clavicle + inter clavicle = wishbone
wishbone
furcula, fusion of two clavicle bones
snake vertebral column
many vertebrae, large range of motion
autotomy
self amputation
