8.1.2.2 - Animal Adaptations

Question 1

Types of adpatations

Answer 1

Adaptation:

• A variation that helps an organism to survive in a particular environment.

Physiological:

• Regulate a function within an organism
  Usually related to functioning of biochemical reactions in cells, e.g. production of venom, metabolic rate, countercurrent heat exchange in veins and arteries,

Structural adaptations:

• Connected to the morphology/phsyical features of an organism
• e.g. beak length, body shape, fur insulation

Behavioural:

• Ways that an animal acts or behaves, e.g. nocturnal behaviour

Question 2

Temperatures of life

Answer 2

• Range at which organisms can be active lies between 0-45C
• If cells cool below 0C they are at risk of ice crystals forming in them
• Above 45C, proteins become denatured so many organisms die past this
• Thermoacidophiles can exist in temperatures up to 110C

Question 3

Endotherm

Answer 3

Animals that can maintain constant body temperature, e.g. mammals and humans

• Use heat produced from metabolism to maintain body temp

Question 4

Ectotherms

Answer 4

Animals that cannot maintain a constant body temeprature

• Temperature changes as ambient temeprature changes
• E.g. reptiles, fish, amphibians, invertebrates

Question 5

Ectotherm example: water-holding frog

Answer 5

• An Australian species of burrowing frogs that live in arid conditions
• Have external fertilisation so must have water in which to mate and produce tadpoles
• Live in temporary pools. As these pools begin to dry up, the frogs burrow down into the soil to escape the heat of the sun, and form cocoons around themselves made from dead skin and mucus secreted from the skin
• This coccon is impermeable to water, so the frog loses little water to its surroundings
• When water from new rains soak down to the frog, the break out of their coccons and make their way back to the surface to feed and mate

Question 6

Ectotherm example: blue-tongue lizard

Answer 6

In summer:

• Avoid high temperature by seeking shelter under rocks and in leaf litter
• Bask on a rock in the morning to increase their body temperature
• Body temperature is maintained between 30-35C

In winter:

• Become inactive during cold weather

Question 7

Endotherm example: red kangaroo

Answer 7

• Occupies central and central western Australia, where summer temepratures are very high and winter temperatures can drop below freezing
• When external temperature is high, they get rid of heat produced by metabolic processes by carrying out evaporative cooling - sweating, or panting
• Lick forearms after jumping, so that when the saliva evaporates, heat also does
• At rest they lose heat by panting. Increased blood flow in vessels supplying these membranes allows a great deal of heat to be lost by evaporation

Water balance:

• Avoid lying in direct sunlight in the middle of the day
• Drink around every 5 days, as rainfall is scarce
• Urine is highly concentrated, as the kidneys reabosrb a great deal of water
• Urinate infrequently during hot times
• Water is also efficiently reabsorbed by the large intestine, resulting in little water loss in faeces
• Only moves in the middle of the day if there is necessity, but otherwise its activity is greatly reduced in the middle of the day

Question 8

Endotherm example: platypus

Answer 8

• Lives in tropical areas in north QLD and cold areas in Tasmania, NSW tablelands, and Victoria
• Poorly adapted to hot conditions when they are out of their burrows or water, and quickly die of heat stress in environment where the external temperature is above their internal temperature

Adaptations

• Tail fat: fat stored in the tail acts as an energy source for body metabolism, which increases to regulate body temperature in winter
• Fur: dense fur traps a layer of air, insulating heat
• Webbed front feet: large surfaces of the webs provide propulsion in water, but there is restricted blood supply here to conserve heat
• Counter-current heat exchange system: veins and arteries flow in opposite direction to exchange heat in the muscles of the pelvic area, reducing heat loss near the rear feet. This is because arteries blood is hot, and blood in feet veins is cold because the feet are in cold water.
• Effect of this countercurrent heat exchange system is that blood flowing back into the core of the body is warm

Question 9

Endotherm evaporative cooling examples

Behavioural

Answer 9

• Panting: hot air flows over the water surfaces in the mouth, causing water from the mouth and tongues to be evaporated
• Gular fluttering: rapid vibration of the throat muscles in birds, equivalent to panting in dogs
• Drenching parts of the body in water: some animals cool down by rolling in water, as the water will absorb heat and evaporate off their body. E.g. African elephants spray themselves with water, and turkey vultures urinate or their legs so that when the urine evaporates off their legs, they will lose body heat

Question 10

Endotherm thermoregulation surface area to volume ratio examples

Behavioural

Answer 10

High SA:V ratio allows for more heat to be evaporated off more quickly. This is usually done by birds

• Flamingoes stand on one leg to reduce the amount of skin that is exposed to the sun, reducing the amount of heat absorbed
• Birds like the double-crested cormorant spread their wings out when standing still → surface area increased, so more heat can be lost to the environment
• Huddling together: penguins huddle together to decrease their SA:V ratio, helping to conserve heat

Effect of environment on the overall shape and proportions of organisms:

• As smaller bodies usually have a higher SA:V and larger bodies typically have lower SA:V, smaller animals tend to be found in hotter climates and larger ones in colder climates. For example, smaller koalas are typically found in northern Australia, like at the top of QLD, and larger koalas inhabit the south of Australia, around the bottom of NSW or VIC. Polar bears also have large body shapes, which creates a lower SA:V and allows it to conserve heat better in the cold environment
• Ear shape: heat can be evaporated off blood through the ears, so larger ear shapes are advantageous in hotter climates. For this reason, animals with larger ears are typically found in regions that have higher temperatures, e.g. jackrabbits in western USA and Mexico. Inversely, organisms living in cooler areas have smaller ears that don’t stick out as much, e.g. polar bears have small ears.

Question 11

Thermoregulation in walruses

Answer 11

They live in Arctic and sub-Arctic regions
* Control of blood flow. Blood flow is restricted to their extremities and blood flow to the organs and muscles is increased, helping to generate heat and maintain a stable internal temperature
* Heat loss in water is 27 times faster than in air. When it is too warm, walruses stay in water.
* Blubber is an energy conserve that can take up to a third of their body mass. It acts as a layer of insulation that can maintain their core temperature.
* Hauling out - they leave the water and rest on ice or land to regulate their body temperature, resting in the sun or shade.

Question 12

Endotherm thermoregulation structural adaptations

Answer 12

• Fur feathers, and hair can trap air against the skin, insulating the body against heat loss due to the convection of air flow. E.g musk ox have extremely long hair. Birds can fluff up their feathers to increase the insulation
• Seasonal coats: some animals produce thicker coats in winter, and thinner coats in summer to regulate the degree of heat loss. E.g. stoats have a distinctive brown-white coat in summer, and a white coat in winter
• Blubber: a layer of fat under the skin surface. This is much more effective at retaining heat than fur coats in cold water. E.g. sperm whales have 15-30cm of blubber under their skin

Question 13

Torpor

Answer 13

• A physiological adaptation to reduce body temperature
• Similar to hibernation in that the breathing rate, heart rate, body temperature, and metabolic rate of the organism is lowered as it sleeps
• However, unlike hibernation in that the organism does not enter a prolonged period of sleep. Torpor usually occurs over a short period of time, such as overnight or for a few days
• Torpor is used by 43% of Australian mammals, usually small ones, to survive cold periods, e.g. echidnas and kookaburras

Question 14

Thermoregulation example: penguins rete mirabile

Endotherm

Answer 14

Overview

• Penguins’ wings have large surface area, causing them to lose heat to the environment quickly. This is especially true when the penguin is swimming in cold water

Adaptation

• Penguins’ blood vessels form a rete mirabile (wonderful net in Latin) of arteries and veins that allows for countercurrent heat exchange
• In the wings, arteries are split into a network (plexus) of multiple parallel branches. Each artery is closely associated with at least 2 veins, allowing blood from the arteries to warm the cold blood in the veins
• Although this causes blood in the arteries in the wings to lose heat, blood returning from the wingtips to the heart are warmed
• This can result in a temperature difference of up to 30C between blood in the wingtips and in the core body