Animal adaptations Flashcards
Marine fish adaptation to osmolarity
100 mosmol/L, conserve water, get rid of excess salts
Freshwater fish adaptations to osmolarity
1-10 mosmol/L, conserve salts, gets rid of excess water
Stenohaline animals
only survive in relatively constant conditions, narrow range of salinity, either marine or freshwater
Euryhaline freshwater animals. Short and long term
Can survive in a wide range of salinity
Short term – estuarine and intertidal
Long term – diadromous (travel between saltwater and freshwater)
Euryhaline anadromous animals
migrating up rivers from the sea to spawn
Euryhaline catadromous anaimals
migrating down rivers from sea to spawn
What is an osmoconformer
internal osmolarity matches external environment
Example of an osmoconformer
hagfish (not many others), they produce a hydrogel (fastest and most dilute) these fibers are strong and flexible.
What is an elasmobranchii
skeleton made of cartilage rather than bone
Characteristics of elasmobranchii
cartilaginous skeleton, 5-7 gill openings on each side, rigid dorsal fins, spiracles to aid in breathing, placoid scales, upper jaw is not fused to their skull
What phylum do elasmobranchii belong to
chordata
What compound do marine elasmobranchs use
trimethylamine oxide (TMAO)
What is ureotelic
the animal excrete urea e.g., marine elasmobranchs
What issue with marine elasmobranchs is there
water diffuses by osmosis from the sea (they have a higher solute concentration). They use salt and urea out of their gills - problem as gradient decreases
Marine elasmobranchs adaptations
reabsorb/retain solutes (e.g., urea), serum osmolarity greater than sea water (hyperosmotic), water gained is excreted by the kidneys, no need to drink
What happens to euryhaline species as salinity decreases
Less TMAO and urea is produced and reabsorbed, more urine, more Na and Cl uptake and reabsorption (gills and kidney)
What is an ammonotelic animal
excrete ammonia as their main form of nitrogenous waste, don’t convert to urea
Features of freshwater elasmobranchs
ammonotelic, dilute urine, cannot make and retain urea and TMAO
What happens as salinity increases to fresh water elasmobranchs
urea production and retention increases. Decreased urea excretion. Increases Na+ and Cl-. Decreases ammonia excretion
What does osmolarity regulation in elasmobranchs require and why
ATP to power Na/K pump
NaCl regulation in rectal gland
K+ channel pumps out (high conc outside the cell). Na/K/2Cl pumped in together. High sodium conc wants to move in but can only enter through that channel carrying K and Cl with it. Raises Cl concentration in cell, move it from the blood to the gut. Gets rid of excess salt
Marine elasmobranch gill movement of ions
- Power comes from Na/K pump
- Na/ urea antiporter driven by high Na concentration
- Na wants to move in and can only do it through antiporter
- When Na moves in it has to exchange with a urea out of the cell
- Membrane changes to conserve urea, so it does not enter the sea water
How is the marine elasmobranch gill membrane adapted
has increased cholesterol and sphingolipids in membrane so it is closely packed and stable to resist urea passing through the membrane
Marine elasmobranch kidney
Counter current multiplier mechanism. 90-95% urea reabsorbed. Probably facilitated diffusion. Urea Na pump. Collecting ducts. Powered by effect on counter current multiplier
How do euryhaline species differ in the kidney
have changes in number of urea pump - more pumps for high salinity
What are the 3 endocrine regulation systems
natriuretic peptide system, arginine vasotocin, renin angiotensin system
Features of the natriuretic peptide system
Increase urine production. Stimulate salt secretion from rectal gland. Inhibit drinking and relax blood vessels
Features of an arginine vasotocin system
increase in plasma osmolarity, reduces urine production
Features of a renin angiotensin system
antagonistic to NP, reduces urine flow, increases drinking, constricts blood vessels
Metabolic costs of endocrine regulation system
ATP required to produce urea. Dietary protein is required. System relies on adequate dietary protein
Characteristics of teleosts
fully moveable maxilla and premaxilla
Teleosts phylum
chordate
Freshwater osmolarity system features
NaCl enters through gills. Avoids losing slat to fresh water. Produces high volume of dilute urine. Conserves salt, avoids water
Marine osmolarity system features
Keep body at lower osmolarity than sea water. Drink water. Actively secrete NaCl. Produce low urine volumes. Reabsorb water from urine. Conserve water and excrete salt
Gill chloride cells in sea water animals
- Power comes from NKA
- Na powers NKCC (Na in carries 2 Cl and 1 K with it)
- Cl conc gets higher than the sea water (leaves through CFTR)
- Na leaves through gap inbetween
5.Needs a lot of ATP - Accessory cells that aid function are present
Gill chloride cells in fresh water animals
- Want salt into their body
- Power still coming from Na/K pump
- If you can get the Na low enough it will move in through a pump/channel
- NKCC, Na moves in so Cl can come in (NaCl into the cell)
- Na into blood, to bring NaCl in
- Na concentration low enough into the cell
Euryhaline - intertidal/eastuarine
both types of chloride cell systems. Kidneys only play significant role in low salinity
Euryhaline - diadromous
hormone mediated, drive adaptations
What can gill chloride cells do
can change morphology of cells and stimulate cell types to adapt them to fresh water or sea water
Affects of adrenaline stress response
increases gill permeability. Increases osmotic challenge
What steps can be taken to reduce impact as part of the stress response
adjust environment to tend toward isomotic conditions, dilute seatwer, add solute to freshwater
Marine mammal water losses
cutaneous, respiration, milk, urine, fecaes
Marine mammal sources of water
from food (can be hypotonic or isotonic with seawater), from seawater, metabolic water.
What do marine mammals not contain
extra-renal salt excreting organs
How can water loss be minimised
reniculate kidney rather than lobulate. Interconnected small kidneys, increases surface area of medulla
How do otriids (sea lions) maintain water balance during lactation
continue feeding, hypotonic prey
How do true seals maintain water balance during lactation
fasting, milk composition changes, reduce water, increase lipid
What other adaptations can reduce water loss
reduce respiratory losses (nasal turbinates, apnea). Reduced/absent sweat glands in some species
What is a poikilotherm
animal whose internal temperature varies considerably
What is a homeotherm
thermoregulation maintains a stable internal body temperature
What is an endotherm
has to use energy to keep warm in a cold environment, in a hot environment needs to use energy to keep cool.
What is an ectotherm
as the ambient temperature rises so does the body temperature, higher temperature a higher metabolic rate
Define adaptation
The evolutionary adjustment of morphology and physiology to changing environmental conditions.
What does natural selection do
adjusts the frequency of genes that code for traits affecting fitness
What is acclimatization
Based on the range of physiological responses present in an organism
What does phenotype plasticity do
gives rise to short-term changes in response to environmental disturbance
What are the 3 basic responses to changes in the environment
avoid, conform and regulate
how can an animal avoid changes in its environment
it may avoid environmental problems e.g., by migrating, or moving to unstressed micro-habitats
how can an animal conform to changes in its environment
it may change its internal state so that it is more similar to the imposed external state e.g., by hibernating or entering torpor
How may an animal regulate to respond to changes in the environment
the animal tries to maintain its internal environment (homeostasis) irrespective of external conditions. This usually requires the use of metabolic energy and/or external resources such as food and water
What us the thermoneutral zone
where the basal metabolic rate is constant
Adaptations to temperatures below the melting point (MP) of the body fluids in ectotherms
- Anhydrobiosis/cryptobiosis - e.g., cysts and eggs
- Virification
- Freeze tolerance – FT
- Freeze avoidance – FA (I.e., freeze intolerance)
Function of posterior hypothalamus
heat production and conservation centre
Function of anterior hypothalamus
heat loss centre
What do peripheral sensors on the skin do
sense temperature - gives us conscious stimulation resulting in behaviour change (e.g., putting on a coat)
Is internal or peripheral senses more important
internal sensing
Relationship between anterior and posterior hypothalamus
both sense blood temperature, when one is stimulated the other is inhibited
Responses to temperature change
Metabolic rate (thyroid). Behavioral e,g., avoidance, eating, huddling. Vasoconstriction/vasodilation. Shunts. Sweating. Arrector pili muscle
Different types of induced thermogenesis
exercise, diet, shivering and non-shivering
Non-shivering thermeogenesis
Heat generation WITHOUT shivering. Futile cycling. Brown adipose tissue: multinocular, fat droplets spread out throughtout the cell. Lots of mitochondria. Pinky/brown - lots of blood vessels
What activates uncoupling protein 1 and what does that uncouple
sympathetic nervous system (noradranline) activates UCP1 which uncouples oxidative phosphorylation
What powers the electron transporter chain
Lipids - beta oxidation
Describe the CAMP cascade
- Triglyceride release of fatty acids which is transported into the matrix of mitochondria- oxidises fats
- Produces electron carriers – NADH and FADH2
- Go to UCP1 to generate heat
- Fatty acids to generate heat instead of ATP
- Increases production of UCP1 – more they are stimulated the better they are at producing heat
Describe oxidative phosphorylation
Proton gradient flows through ATP synthase to generate ATP. However different path taken – go through UCP1. Porton potential is dissipated – turning into heat
What does brown adipose tissue respond to(BAT)
temperature and diet
Diet reduced recruitment in mice
BAT recruiting diet -> increased voluntary food intake -> increased obesity -> chronic BAT stimulation -> BAT recruitment ->
Repeated single meals -> (increased glucose, insulin, CCK, enterostatin) -> repeated BAT stimulation
Where is more BAT found
younger people, women, skinnier people
Brown adipose tissue (BAT) is…
hard to detect in diabetes, cold responsive, inducible?
Function of 2,4-dinitrophenol
crosses the inner mitochondrial membrane and carries H+, Uncouples oxidative phosphorylation. Proton motive force dissipates. Increased O2 and NADH consumption
Dinitrophenol side effects
weight loss
What is dinitrophenol used in
herbicides, fungicides and explosives manufacture
What animals have fins
all jawed fishes (except eels) have pectoral and pelvic fins, aquatic vertebrates
sTRUCTURES IN WHICH FINS OCCUR SINGLY
DORSAL, ANAL AND CAUDAL
Ways in which fins occur in pairs
pectoral and pelvic fins. Paired fins are the phylogenetic source of the tetrapod limbs
Function of fins
- Stability - Fins projecting from streamlined body. Prevent: pitch, roll and yaw
- Braking action - Paired fins
- Steering - Control direction of movement (‘rudders’)
What a modern fishes fins composed of
basal pterygiophores, radial pterygiophores and dermal fin rays
basal pterygiophores (proximal)
3 large elements that articulate the fin to the pelvic or pectoral girdle
Radial pterygiophores (middle)
smaller more distal elements
Dermal fin rays (distal)
slender rods, keratinized in elasmobranchs, ossified or chondrified in bony fishes
Different types of paired fins
- Ray fins – very flexible with thin base (Actinopterygii)
- Fin-fold fins – very broad based (chondrichthyes)
- Lobed fins – fleshy muscular lobe at base – makes them more flexible (sarcoptergii)
Lobe-finned fish class
sarcopterygii
What are representitives of lobe finned fish
coelacanth and six species of lung fish
Sarcopterygian fish fins
have a central appendage in their fins containing many bones and muscles. The fins are very flexible and potentially useful for supporting the body on land
How are the fins connected to the girdles
by a continuous chain of bones that are homologous to tetrapod limbs
What are the 2 groups sarcopterygian fishes are divided into
crossopterygians (the coelacanths) and dipnoi (the lungfishes)
How is forward propulsion in fish achieved
by lateral flexion of vertebrae caused by axial musculature
What does the forward propulsion of fish create
lateral undulations - tails sweeps side to side exerting a forward and lateral force against the resistance of water
What does the forward force do to fish movement
propels fish forward
What does the lateral force produced do fish movement
makes the body of the fish move sideways but this is minimised by the fact that the body is large and its inertia is more difficult to overcome
How do lateral undulations of fish help movement on to land
Lateral undulations and peg like fins act as pivots around which the body could rotate. “bottom-walking” of today’s lungfish use fins as pivot points about which buoyant body moves
Lateral undulations in water
Propulsion through lateral undulations; Horizontally held fins -> LIFT . Vertically held fins -> THRUST
Lateral undulations on land
Same lateral undulations place fins as pivot points; body rotates around pivot; limbs not as strong as tetrapods (not carrying body weight, no real locomotory function)
What is the function of limbs
locomotion, tool (e.g., mole, cat)
Evolution of limbs
Generally accepted that early tetrapod limbs developed from lobe-finned crossopterygians (coelacanths)
what is the best known fossil from the transition from lobe-fins to tetrapods
acanthostega then tiktaalik
Why is tiktaalik a better fossil to show this evolution
More primitive lobe-fins had shoulder bones that only allowed them to paddle back and forth in the water. Tiktaalik could support itself, bending its wrists to lay its hand-like bones flat on the water bottom. Its powerful ribs and spine gave it more support, and with its eyes stuck right on top of its head, it could look at prey (or predators) swimming overhead
What does tetrapod in Greek mean
four footed
What are the 4 classes of tetrapod
amphibians, reptiles, mammals and birds
What is the similarity between tetrapods
tetrapod limbs have same basic plan despite superficial differences (e.g., legs, wings, flippers)
Describe early tetrapods
evolved from lobe-finned fishes. Short limbs. First segment almost horizontal. Second segment perpendicular to first (vertically down). Toes tended to point laterally
Early amphibian terrestrial locomotion
to lift and plant foot è then tetrapod vertebral column rotates about the pivot point (still used by lizards and turtles)
What new factor did lifting a limb bring
axial torque of vertebral column
What movement can a primitive gait cause
trot - simultaneous placement of diagonally opposite feet on the ground
How is extra stability gained
Buoyancy (in water)
»Tail on ground
»Belly walking (ventral surface remains in contact with ground)
Tripodal – placing tail on ground produces triangle of support:- increased stability
Lateral sequence gait also increases stability -> C of G always within triangle of support formed by 3 legs
How can locomotion be insufficient
sprawled posture (in reptiles and urodeles) is inefficient energy expenditure. Overarm swing with each step, body weight supported by adductor muscles, limbs therefore drawn under body
How has an animal been adapted for bipedalism to improve efficiency of locomotion
front legs modified, hind limbs lengthened and strengthened, knees rotated anteriorly to a position essentially beneath body
What is bipedalism
where a tetrapod moves by means of its to rear/lower limbs
How has an animal been adapted for four-footed gait to improve efficiency of locomotion
knees rotated anteriorly. Elbow rotated posteriorly and brought closer to body
What is a four footed gait
each foot hits the ground independently
What are the advantages of changed limb posture
1.Body weight now supported by rigid bones è decreased energy expenditure
2. Increased efficiency of limb swing è limb movement in sagittal plane - easy pendulum swing beneath body
3. Change in flexion of vertebral column from lateral flexion to vertical flexion (and extension) è increase in stride length = Quadrupedal gait!
Modes of terrestrial locomotion
Cursorial, Fossorial, Saltatorial (ricochetal), Arboreal (life in trees), Brachiation, Locomotion without limbs, Unique modes of terrestrial locomotion
Cursorial examples
Fast running e.g., antelope, horse, cheetah, some lizards, Carnivores
Fossorial examples
Digging e.g., moles, rabbits, sand snake, some rodents
Saltatorial examples
hopping e.g., kangaroo, frog, hare
Arboreal (includes both scansorial and brachiation) examples
Scansorial (climbing with claws) e.g., squirrel, nuthatch. Brachiation - (hand grips branch and body swings beneath) e.g., monkeys, chimpanzees
Locomotion without limbs examples
snake - Lateral undulation / serpentine, Rectilinear, Concertina, Sidewinder
Fossorial adaptations of digging/burrowing
- Body contour (fusiform body)
- Reduction of tail
- Loss of eyes
- Disappearance of ears or pinnae
- Digging mechanisms
Fore limbs - burrowing movements
Short and stout, Long claws suitable for loosening the earth. Foot serves to drive the creature ahead and to resist the backward thrust received from the hands.
Lateral undulation - locomotion without limbs
Most common. Large dorsal muscles are activated sequentially along the body (Unilaterally)
Rectilinear - locomotion without limbs
Straight line movement. Large snakes such as large vipers, boas, and pythons. The belly scales are alternately lifted slightly from the ground and pulled forward, and then pulled downward and backward.
Concertina - locomotion without limbs
Alternately pulling up the body into bends and then straightening out the body forward from the bends.
Sidewinder - locomotion without limbs
Muscle activity during sidewinding is similar to that in lateral undulation except that some muscles are also active bilaterally in regions of trunk lifting
What is a stride
full cycle of running or walking animal
What is cursorial
running movement - mainly about speed
What causes an animal to travel faster
A faster rate of limb oscillation
Speed formula
length of stride x rate of stride
What is the relationship between length and rate of stride
antagonistic - enhancing one compromises the other
How can the length of stride be increased
lengthen the distal limb elements. Radia and tibia are usually longer than proximal segment. Light and slim (tendons rather than muscles)
What are the 3 types of foot posture and what do they favour
plantigrade (favors walking), digitigrade (favors running), unguligrade (favors running at high speed)
How does foot posture effect length of stride
it alters the length of the limb
What other adaptations can increase length of stride
highly mobile shoulders, absent or reduced clavicle, scapula more mobile/ oriented to the side - invcreases the distance through which the limbs move
What animals have lateral flexion
lizards and amphibians
What animals have vertical flexion
fast quadrupedal mamals
What do the back muscles do
flex the spine bring hindquaters under the body just before the hind legs reach the ground
What does an extended back do
Body longer when back extended – achieved when back feet on ground – increase in length added to stride length
What does an increase in back flexion and extension do
increase rotation of girdles -> increase swing of legs -> further back and further forward -> increases stride length
Why can a horse win over long distance against a cheetah
Loosely articulating vertebrae. Massive energy use to displace vertically – energy expenditure
How to increase rate of stride
larger/more efficient muscles. Shortening limb
What can increase efficiency of muscle movement
Lighten distal end of limb (decrease inertia that must be overcome) - reduced muscle mass, reduced digits
More easily and efficiently moved with less energy
Why is the site of insertion important
If muscle shortens by same length:
Proximal insertion – moving part swings through large distance
Distal insertion – moving part swings through small distance
How many digits do mammals have
1-5
What many digits do rodents, rabbits and carnivores have
walk on 4
What many digits do rhinos and tapirs have
3
What many digits do pigs, sheep and camels have
2
What many digits do horses have
primitive had 4, modern has 1
What are gaits
patterns of footfall, regularly repeated sequence. Most have a variety and select use based on speed, terrain, energy efficiency and need to maneuver
Examples of gaits
walk, amble, trot, pace, center, gallop, pronk and half bound
Walk
4 independent footfalls
3 point support
Footfall sequence: right hind, right front, left hind, left front; repeat
Amble
“sped-up walk
Transitional between a normal walk and a trot
What animals do when constrained to walking but when they want to move fast
What animals do when they are very large and can’t truly trot
Trot
two-beat gait, 2 point support
Right and left diagonals alternate in supporting weight, I.e., the right forelimb and left hind limb move in unison as do left forelimb and right hind
Usually in animals with broader body (e.g., horse) or lizards with splayed legs
Pace
The pace is a two-beat gait, 2 point support
The 2 lateral limbs are used alternately for weight support, I.e., the left forelimb and left hind limb move in unison, as do both right limbs
Long-legged animals (less interference between back and front leg)
Unstable in short-legged animals
e.g., camel, giraffe (horses)
Gallop
The fastest of all gaits. 4 beat gait
Generally have period of suspension when: legs gathered under animals (horse), legs stretched out fore and hind (deer), both (cheetah and pronghorn)
Horse derives momentum and speed mostly from its hind limbs
Cheetah derives momentum and speed mostly from its forelimbs
Gallop type is determined by the energetic cost
Equine transverse gallop, cheetah rotary gallop
Pronk
All 4 feet on ground simultaneously
Then period of suspension
Abruptly jars and decelerates the animal
Great 4 footed stability
Social display or defensive behavior
Human locomotion
Bipedal
Walk to run
Economy of effort above or below 5mph
Change gaits: energetic costs at a minimum
Upright posture: fundamentally unstable – 2 supports only, large part of body weight above centre of gravity
What are the 3 changes to achieve upright posture
1.Front of body lifted 30 degrees
2.Upper part of pelvis tilted back, rotating vertebral column another 30 degrees
3. Lumbar region of vertebral column curves the last 30 degrees -> upper body now upright
Symptoms of lordosis
arched lower back, lower back pai, pelvis tilts forward, weak buttock muscles, bottom sticking out, hard to stand uo straight, front of hips tight
Shape of spine/ vertebrae for humans with lower back problems/ disc problems
more similar to a chimpanzee
