Endothermy/ectothermy

Question 1

Poikilothermy

Answer 1

Organisms that allow their internal temperature to fluctuate substantially

Question 2

Homeothermy

Answer 2

Organisms that stay at the same temperature all the time

Question 3

Most mammals can be considered to be ___________/____________

Answer 3

Endothermic homeotherms

Question 4

Many marine and terrestrial invertebrates are ______/______

Answer 4

Ectothermic poikilotherns

Question 5

What type of organisms are rare? Example?

Answer 5

Endothermic poikilotherms

Naked mole rats

Question 6

Eurytherms

Answer 6

Can tolerate enormous range of temperatures, 20-30 degrees around normal

Question 7

Stenotherms

Answer 7

Animals are intolerant of large temperature fluctuations

Eg Antarctic animals

Question 8

Homeoviscous adaptation

Answer 8

Changing proportions of saturated/unsaturated fat composition of membranes in response to changes in temperature

Question 9

Kleptothermy

Answer 9

Huddling to share heat

Question 10

Mesothermy

Answer 10

An intermediate between ectothermy and endothermy

Currently thought to be used in dinosaurs which then led to endothermic birds

Question 11

Uncoupling protein used in brown adipose tissue is?

Answer 11

Thermogenin

Question 12

3 means by which heat is lost/gained

Answer 12

Conduction, convection, radiation (and evaporation)

Eg. Radiation from sun, conduction from heated rocks or volcanic vents

Question 13

How does colour influence heat gain in pigeons?

Answer 13

Low wind speeds: black gain more than white

High: black tends to lose more heat

Question 14

Thermal stability of water:

Answer 14

Aquatic organisms subject to colder, more stable temperatures

Size of marine environment buffers extreme heat increase and limited at lower end at water freezes (-1.8 for saltwater)

Greater range of temps in fresh water as tend to be shallower

Question 15

Ectoderm cooling:

Answer 15

Tend to be passive and can be described by and exponential time constant

Hearing is usually slightly faster than this as there is an active component: pumping blood towards skin

Eg. Iguana basks in sun and pumps blood

Question 16

Heat loss in water is due to:

In air due to:

Answer 16

Convection

Conduction

Question 17

Relationship between heat loss and surface area in water:

Air:

Answer 17

Linear

Curved: smaller animals are more likely to lose heat through convection and larger through conduction

Question 18

Draco and Anolis lizards

Answer 18

Draco and anolis (forest): thermoconformers

Anolis (sun) tend to have slightly higher than ambient body temperatures so must regulate temp in some way

Question 19

The marine iguana is a:

Answer 19

Ectothermic homeotherm

Spend most of their time basking

Cool down when in water- limbs colder than body

Limits foraging time

Have to have small surface area to volume ratio so don’t cool down too quickly

Question 20

Many ectotherms undergo daily cycles

Answer 20

That roughly follow the cycles of ambient temperature

Eg. Monitor lizard: long periods of stable temperature, cools down at night but heat up towards morning. Fluctuation in ambient temperature which is lower than body temp means temp is regulated

Question 21

Ectotherms sometimes move positions to adjust temp to preferred level eg

Answer 21

Desert iguana in lab preferred temperature set up

Question 22

Behavioural fever

Answer 22

Deliberately move into hot temperatures to induce fever

Question 23

Monkey tree frog

Answer 23

Epidermal wax melts above 38 degrees so they can stabilise their temp using mucous glands

Wax prevents water loss but when it melts at high temp allow evaporative cooling

But lose lots of water and can’t always cool- often die in il nino

Wax distasteful to predators

Question 24

Zone of resistance

Answer 24

Area in which animal can survive very high temperatures for short periods of time

Question 25

Enzyme activity

Answer 25

Can be adapted to temp Homologous proteins vary in enzymatic activity at diff temps but the same when in animals normal temperature

Question 26

Can express different _________ of enzymes eg _______________ On long timescales, may be expressed both temp isoforms at intermediate temp

Answer 26

Isoforms Acetylcholinesterase Don't always express more active "winter" isoform due to symmorphosis, too much energy, waste products may be toxic

Question 27

Artic, sub arctic or northern temperate ____________(fish) use:

Answer 27

``` Teleost Glycoproteins or polypeptide antifreezes to suppress growth of crystals in tissues effective at low concentrations typically v potent Operate in small temp range Other fish supercool body fluids ```

Question 28

Brown adipose tissue contains

Answer 28

Many mitochondria for uncoupling to produce substantial heat increase

Question 29

Some animals keep their temperature _______ when ________ but let it _________ for the rest of the year. Some small __________ and ________ let their temperature __________ in the night but ________ in the day

Answer 29

``` Constant Mating Fluctuate Mammals Birds Drop Regulate ```

Question 30

How is endothermy characterised?

Answer 30

Temperature at which metabolic rate is stable and temperatures where it increases dramatically

Question 31

Describe the characteristic j-shaped curve of endothermy

Answer 31

Preferred temperature (thermoneutral zone): flat line as metabolic rate is stable Above/below: metabolic rate increases to allow work to maintain temperature Upper critical limit: above thermoneutral zone Lower critical limit: below thermoneutal zone- slope of this is the animals conductance Arctic species has large thermoneutral zones and shallow slopes as low conductance (due to fat/fur)

Question 32

Thermal adaptations

Answer 32

``` Modify behaviour Vascoconstrict/dilate Shivering/non-shivering thermogenesis Swear Uncoupling protein ```

Question 33

Insects

Answer 33

Can shiver by uncoupling flight muscles and wings

Question 34

Birds

Answer 34

Contract feathers to trap more air and reduce conductance

Question 35

Why do marine mammals invest more in blubber?

Answer 35

Fur would reduce hydrodynamic shape

Question 36

Evaporative cooling

Answer 36

Cost of substantial water loss when panting/sweating

Question 37

Gula flutter

Answer 37

Rapid movements of buccal area whilst increasing blood flow to improve evaporative cooling Birds can also pant

Question 38

Dromedary

Answer 38

Dehydrated: stares a lot of ambient heat, loses more water through evaporation but not enough to combat extreme heat Hydrated: huge amounts of evaporation offset heat gain from environment, body temp fluctuates less

Question 39

Kangaroo rat

Answer 39

Temporal countercurrent exchanger in nose Reclaims water in exhaled air but cooling the air with fresh, inhaled air Condenses on nasal wall

Question 40

Directing blood

Answer 40

Shunts and countercurrent exchange Eg. Penguins have a counter current exchange system in which cold blood coming up from the feet is warmed by fresh blood moving into the feet. Stop heat loss from feet in contact with ice Carotid rete in dogs: counter current exchange so hot blood doesn't go into brain

Question 41

Diurnal cycles

Answer 41

Willow tit: turns off metabolic heat at night to save energy, rises in anticipation of morning

Question 42

Short term heat evasion:

Answer 42

Hiding (jerboa) Wallowing (hippos) Kleptothermy (mountain goats/sheep, penguins, bees)

Question 43

Opah

Answer 43

Moon/teleost fish First truly endothermic fish (tuna can generate heat but only when contracting muscles) Has large heart, large amount of muscle and blood through whole body- not expected for its cold environment Heat from constant/quick flapping of pectoral fin Elaborate insulated rete allows the blood to be warmed by flapping- blood leaving hills warmed, out is cooled Full arch surrounded by white adipose tissue Countercurrent Don't need to come to surface for warmth or to gulp (completely separate swim bladder) Operates at deep, cold waters with high nutrient content

Question 44

Evolution

Answer 44

Thermogenesis may have evolved to maintain temp during incubation/development to maximise growth (not crocs- sex determination) Ancestrally, all tetrapods ectothermic and birds and mammals evolved endothermy, lepidosaurs (reptiles that didn't lead to birds) didn't Probs evolved to lower temp before increasing it

Question 45

Facultative endothermy

Answer 45

Indian pythons Females wrap body around eggs when incubating and contract trunk muscles to shiver Only when incubating Not true endothermy

Question 46

Tegu lizards

Answer 46

Elevate body temp during reproductive season (October) Still fluctuates with daily fluctuations and in temp of burrow but always slightly higher body temp Thermogenesis correlates with heart rate suggested metabolic rate causes elevated body temp but also changes to conductance Heterothermy, mesothermy and poikilothermy

Question 47

Californian ground squirrel

Answer 47

Pumps blood to tail to signal to rattlesnakes they have been seen