Lesson 14 Flashcards
are ectotherms usually just as warm as endotherms
yes
endothermy
- create body heat from within
- high metabolic heat production combined with insulation
- if you don’t insulate, what’s the point of heat production
- all chemical reactions produce heat and the less efficient they are the more heat they produce
- heat is always a product of metabolism
- the presence of insulatino is CRITICAL for being an encotherm
- why do we care how warm we are – many of our internal chemical reactions are temperature dependant
- faster chemical rxn can mean faster cognitive thinking/processing, digestion…
- out outside is changing also — not as much if aquatic
ectothermy
- animals do not have a high metabolic heat production and generally have little insulation
- use behavioral adjustmaents and some physiological adjustments
ex: the luzard will angle body in direction of direct sunlight
ANGLE is very important – the angle of the earth
– applies to the small animals as wekk - turning to get direct rays
- convection via air around it (heat rising)
- conduction via air and ground (touching)
- infred exchange with the sky and with rocks and other rocks around it
- animal can move between the sun and shade –> also orient differently
how does body temp affect behavior
– because it affects the speed of chemical reactions
– ex:
——- digestion
——- swimming speed
——- O2 consumption
some ectoderms can
- disperse pigment (melanin) from melanophores up into the process that darkens the skin –help the animal take up more heat – darkening skin
ectoderms and blood flow
- if you have blood very close to the skin – that blood is coming from the core of the body and the heat is being lost through the surface of your skin near your fingers
- what if you could turn off the blood flow to the areas with large amounts of surface area
WE DO IT – when our fingers go numb
lizards and their 3 factrors
- if warm on the inside and cold on the outside, then you might think that they should open up the blood vessels and dissipate heat
- even though the animal is warm, it doesn’t mean it’s warm enough
- have to reconsider its ideal temp
- should do the exact opposite
if the animal is warmer than it needs to be and the surrounding is colder,
you should open up blood vessels to cool down body temp
if body is warm, but not warm enough and the outside is cooler,
should not open up blood vessels and not allow for the more distal areas to get blood
when and whether an animal uses vasodilation, must consider 3 factors
- body temp
- ambient temp
- target temp
desert tortise
endangered – people have them as pets tho
- facing a lot of habitat loss, regular plant food supply has been lost from weeds that were not supposed to be there
- affected by dust and dirt – off road driving stirring up dirt, affecting respiratory
desert
potential for water loss exceeds water input
- lot of variation betwen temoerature and enviornment from day and night
in the mohobi desert
ground temp annually ranges from 0 to 50 degrees Celsius
- if you go 1 meter below the surface, you are only dealing with a 15 degree range
- therfoer lots of desert organisms live underground where the temperature fluctuations are greatly limited
- characterized by water scarcity - scarcirty of plants — scarcity of inscets
doubly labeled water technique
- quanify in animals metabolic activity – for weeks or months
—- energy expenditure when in the wild – no testing in the lab
^^ can answer with this techniuw
1st - appreciate the basic stoichiometry of metabolism
C6H12O6 + 6O2 –> 6H2O + 6CO2 - to do this water is made of isotopes of hydrogen and oxygen that are not normal
— The different water made with different isotopes are made in the lab and injected of a known volume of doubly labled water
—-What becomes of that water → over time there is a dissociated of the H and O ions – become spread throughout the whole body
—-Over time the injected water does get lost (gets metabolized) and gets excreted or evaporated, or breathed off
—-Eventually they leave the body —> O leaves through 2 routes, H leaves through 1 route – depending on how much metabolism has occurred the difference in the loss between H and O will change and can be computed
The degree to what they’re different will depend on how much time has passed and also the animal’s metabolic rate
- if the animal was involved in a lot of activity - the difference will be greatest
- calibrated to how much time has passed and can compute the amount of metabolic activity
drinking water
- certain small mammals in the desert never drink water
- all animals need water
- OPTIONS TO GET IT
- get water from plants (water in the cells of those plants)
- or they can make water
- all they did was take on glucose, breath in O2, and make water –> they can metabolically produce wter
- mostly how a lot of desert dwellers obrain water
for a chuchwaller
- chart tells us how much water is produced for what they eat
- fat produces the most water per gram
- in the dead of summer –> the chuckwaller barely emerges from underground
—- too hot
seasonal changes in water balance of chuckwalla
- almost no food in september
- much more food in may
- most of water comes from what they eat, little is metabolized
spadefoot toad (common desert amphibians)
- have permeable moist skin (becasue it is an amphibian)
BUtttttt their moist skin is not a handicap - they will dig these burrows that are damp in the ground –> it makes the burrow very humid —>allows them to take up water
- helps animal as ling as a lot of time is spent in the burrow
tadpoles of yellow legged frogs
- each dot shows position of tadpoles throughout the day
- note that its pretty chilly at 9 in the morning but less chilly at the bottom, so they all huddle at the bottom
- at 10 in the morning, warmer at the margins than the bottom – move to edges
hebron sound
big body of water off the coast of laberor
- have different strategies for surviving the cold
- temp of deep water doesn’t mate if it’s summer or winter
- animals do not freeze
- for something to freeze some crystilization must form
- you need a nucleatoer – you need some solid object ex: a grain of sand –> for ice crystals to grow around
- the deep waters of the hebron sound are so pure that they lack nucleators and there is nothing for the ice crystals to grow around
SUPERCOOLING
- ice does form around the top though
- animals above the deep water do not supercool – they make their own anticoolant to precent themselves from cooling — will synthesize low molecular weight antifreeze that will prevent them from freexzing
- some vertebrates tolerate frozen tisue
—– the wood frog is capable of tolerating frozen tissue
huge difference between endotherms and non endotherms in terms of energy usage
no bird or mammal is actually 1g of body mass (not true for ectoderms)
WHY^^^
- it is too expensive
- they have similar upper boundaries
- but when it comes down to the funamental property of SA and VOlume
– small objects cool off faster
– they give less thermal inertia
– small objects relative to the numebr of things that are making heat loss a lot of it
– being so small as an ectoderm – they get their energy from outside, and it is energetically favorable to be an ectoderm – to small to be eficient for an endoderm
no flat kind of shapes for endoderms
- more SA – more susceptible to heat loss
efficiency numbers
how good are these tissues in the body as using energy
– ultimately all energy converted into heat
^^^^ the goal for endotherms, but terribly inefficient for other processes
- turbinate bonds in the nasal passages that provide a large moist surgace
- the need to insulate –> presence of hair –> mammals (mostly) or aquatic mammals use blubber
- in surapsids they have feathers
endotherny
- high production of metabolic heat
- need isulation
-problem for evolution
—- dammed if you do, dammed if you dont
if you have all this insulation but are not producing heat = selected against
—- if you produce all this heat but have insulation = selected against
-
HOW has endoterny evolved
- hypothesis that it evovled in herbivoers
- herbivores inherently have a problem
- they eat a lot of carbon and the body does not need that much
- herbivores tend to eat the quantity of other things that they need ex: nitrogen, which is on low amounts
- what do you do with all that carbon that you don’t need —— you BURN it off with that high metabolic inefficiency –> byproduct is heat
– then you need to dissipate that heat
^^^ letting the organism be more active in general upholds those high speeds
turbinates
- enable a keen snese of smell due to the surface area in the tubunates
- help to capture and slow down the movement of air that is carrying a lot of moisture and heat
- warmer air coming out of mouth and nose
teeth instead of muscular gizzard
- jaws break it down to easily digestible bits – increase surface area
only find turbinates in later groups of endotherms
were larger dinosaurs endotherms —> probably gigantotherny
—– maintained body heat but they did it by being so huge and having very little surface area
- skin type of ancestors dictated hair v. feathers in one group
2 functions of body heat regulation - endotherms
- one showing the change of body temp and one of metabolic rate relatice to the range of environemntal temp
- endotherms have the ability to maintain their body temo
- also in certain areas, endothersm can maintin their metabolic rate
- window where endotherms can maintain their metabolic rate where enegy expenditure is basicaly free
– curling up or branching out
– sweating
There comes a point where postural and behavioral modifications are insignificant for maintaining body temp and metabolic rate
we
– shiver
– contract superficial blood vessels
why is there an increase in metabolic rate when going from lower to critical and lower to leathal and maintaining body temp
- why does body temp drop
- if body temp gets too cold, bodily reactions can’t take place
- snowball effect
- in birds – gulard fluttering (like panting)
- causes air to pass over moist endotherlial tissue of the area and drive evaporation
metabolic rate
- point of inflection where the curve is flat then it kicks up
artic mammals
- some have really good insulation
- don’t have to deal with nearly as much temp change internalluy
- can have a much lower critical () temp?
grey whale migration
- in the summertime they are up in these polar waters
- they feed ravenously in preparation for winter
- they come down for calfs
- almost no feeding in the winter
lots of birds mugrate to try and get around the cost of lack of food in the winter
torpor
- animal will go through a period of low activity to drop its body temp and can save a lot of energy (kind of like hibernation)
black-capped chickadee
- would require almost 1 gram of fat to keep a normal body temp through the night of winter
- animal is barelt 5 or 10 grams total
^^ it tolerates a drop of body temp – it undergoes torpor
hummingbird
doesn’t eat that much in winter because the flowers close up
ground squirrel
goes in and out of torpor before entering hibernation
– a lot of energy is saved in torpor
there are also endotherms in the hot desert
- some challenges are to be able to keep cool
- ability of some animals can tolerate higher body temperatures
- many desert animals are either really large , but many are also quite mobile
— flying large distance can help water search
whats going on with camels pressed up against eachother
- SA TO V RATIO – heat moves down thermal gradient across surface areas
- animals are sometimes in a situation where its hotter outside than it is inside
- not good because heat goes from high to low
- resuces the SA where heat can enter by pressing up against eachother
gazelle
has a unique countercurrent heat exchange to keep brain cool
- as it breathes cool air in, get some evaporation that cools blood going to the brain, blood leaving the brain is warmer
some other animals `
- avoid heat by being nocturnal
- ## or live underground most of the time
cape ground squirrel
can shut off blood to tail and use it as a parasol (umbrella)
can birds normally tolerate the higher temps
yes
wild zebra finch
time breeding specifically when the rainy season comes
sand grouse
- mother has its young strip water from its specially coilded water holding feathers
- she soaks the water up using feathers when she flies
