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cos they are cold blooded and use there stored energy up very quickly
 
Cause they get tired easily. I mean, you try not using your arms and legs and see how long you can be on the go for. :)
 
Being an ectothermic animal (cold blooded) they conserve there energy for more productive things like seeking food etc.If they sense that there is no food nearby they will use what little energy they have to soak up as much warmth as possible before going out for a hunt.
 
I. Body Size and Metabolism


A. For almost all animals, metabolic rate increases with size, but not as quickly as size
> B. Kleiber relationship: VO2= a mb, where VO2 is rate of oxygen consumption, but could be other measures such as total calories expended, a is a proportionality constant which differs among taxa for example, it is much higher in homeotherms than in poikilotherms, and b is an exponent, which is 0.67 [Kleiber relationship, by definition] and is -0.25 when plotting mass-specific metabolic rate (e.g. VO2/gram). Plotting VO2 and mass on a log-log plot, the slope equals the exponent (b).


II. Body Size, Metabolism, and Thermoregulation (McNab, B. 1983, J. Zool. 199(1))


A. The Kleiber relationship does not always hold for small mammals


1. Follow Kleiber (or fall below) and the animals show obligatory torpor

2. Increase above Kleiber and maintain endothermy


B. Minimal boundary curve


1. For endotherms it defines the difference between true endothermy and obligatory torpor

2. At a larger scale, the same curve defines endotherms and ectotherms


C. Reptile endothermy


1. Endothermy is merely a function of size * metabolic rate

2. Any animal with a small size can be endothermic if its metabolic rate is high enough

3. Any animal with a low metabolic rate can be endothermic if it is large enough.

4. Examples:


a. Python molorus: Through shivering thermogenisis while brooding they can maintain its body temperature 7 C above ambient. Comparison of metabolic rates when and when not brooding fall on either side of the minimal boundary curve.

b. Dermochelys coriacea (leatherback seaturtle): Can weigh 750 kg and maintain and 18 C differential with the environment. There are no measures of active metabolic rate.

c. Given the size of dinosaurs they would almost have to be endothermic.


III. Aerobic versus Anaerobic Metabolism


A. Energy is released by the breaking of high energy phosphate bonds of ATP, can be released in two ways (but there is a third)

B. Anaerobic Metabolism (Glycolysis): releases energy by fermentation of glucose to pyruvic acid, which then is converted to lactic acid.


1. Advantage: Does not require oxygen, thus can release energy very quickly, excellent for burst activities.

2. Disadvantage: Can only support activity for short periods of time before an oxygen debt accumulates; inefficient (below)


C. Aerobic Metabolism: releases energy by oxidizing pyruvic acid through the Krebs cycle and Oxidation.


1. Advantage: Can support activity for long periods of time and is very efficient relative to anaerobiosis (18:1 ATP yield)

2. Disadvantage: Requires a high and constant supply of O2.


IV. Metabolic Support of Activity: Herps versus Birds and Mammals


A. Endotherms can maintain high levels of activity for extended periods of time. E.g. in the cheetah it is the internal heat generated by the muscles rather than O2 depletion that limits performance

B. Herps exhaust quickly, and most of their activity is characterized by non-movement punctuated by short periods of movement. 50-98% of energy used to support high levels of activity are generated anaerobically.

C. Differences in aerobic capacity are due to the higher resting metabolic rates in endotherms, which make available a high and constant supply of oxygen to support aerobic metabolism.


V. Advantages of Low-energy Approach to Life


A. Lower resting rates means less energy needed


1. Metabolic rate of fence lizard (Sceloporus) at its activity temperature is 13% that of a similar sized endotherm. Since the lizard is not at its active temperature much of the time, the daily energy requirement is only 3%.


B. Lower metabolic rate allows smaller body size


1. Since metabolic rate is relatively higher for smaller endotherms, there is a severe limit to small size. Apparent from McNab's work as well as the general observation that small shrews, hummingbirds and bats can all die in traps and mist nest from starvation and hypothermia in short periods of time.

2. Herps are much smaller than birds and mammals, this obviously allows occupation of different adaptive zones.


C. Less energy allows dependence on temporally clumped resources


1. Egg-eating lizards (Heloderma) and snakes (Dasypeltis) can go months without food between nesting seasons of birds.

2. Desert geckos (Coleonyx) can store 9 months worth of food in 4 days of ad lib feeding.

3. Spadefoot toads (Scaphiopus) are active only during summer rains in the desert, and can spend 8-9 months underground, or even years, waiting for rains.


D. Less oxygen required so animals can survive longer in anoxic environs


1. Iguana iguana perches on branches overhanging water. They escape predators by jumping into the water and can stay submerged 4.5 hours.


E. High ecological efficiencies


1. Less energy goes into maintenance of metabolic rate so more energy available for secondary production.

2. No endotherms in table have net efficiencies greater than 2%, all herps (but python) are greater than 20% and the salamander Desmognathus ochropheus can be as high as 98%.

3. In the Hubbard Brook ecosystem, the energy intake of the red-backed salamander Plethodon cinereus is 0.20 that of endotherms of the same size but it total secondary productivity is equal.


VI. Metabolic Correlates of Activity


A. Main question: Is there a relationship between the level and kind of activity in which a species engages and the ability to physiologically support that activity?

B. Anurans: foraging mode


1. Aerobic capacity: here refers to max VO2 during forced locomotion; previously this measure was referred to as max VO2, but it was found that VO2 calling can be higher

2. Foraging mode: sit and wait versus active


a. Electivity: the degree of specialization on a particular food item. Higher electivity on ants implies more active foraging.


3. Linear correlation between electivity and aerobic capacity.

4. Question: Reflects differences in energetic demands of foraging?


a. aerobic capacity is correlated to distance moved.

b. prey capture attempts increase with distance moved.


C. Anurans: ontogenetic changes


1. Adult frogs are able to perform saltatory locomotion for relatively long periods without exhaustion.

2. Species that metamorphose at a larger size have aerobic capacities that are similar to adults after being adjusted for body size (Rana clamitans and Rana palustris need to grow 20-fold to reach adult size).

3. Species that transform at a smaller size have aerobic capacities much lower than that expected from the adult capacity (R. sylvatica [50x], Bufo americanus [2000x]).


a. Bufo americanus exhaust in 30 sec of locomotion.


4. Species do not attempt to disperse from the pond until they undergo a rapid increase in aerobic capacity


a. in Bufo americanus this is accompanied by drastic increase in heart size and hematocrit.


5. Ecological correlates: species that are much smaller relative to adult size reside in temporary ponds, and cannot afford the risk of a longer time to (and larger size at) metamorphosis.


D. Lizard foraging modes


1. Eremias lineoocellata, Meroles suborbitalis are sit and wait

2. E. lugibris, E. namaquensis, Nucras tessallata are active

3. Is endurance capacity related to foraging behavior?


a. E. lugubris has greater time to exhaustion on a treadmill

b. E. lugubris can endure higher speeds longer


4. Is sprint capacity related to foraging behavior?


a. E. lineocellata has higher burst (initial) speed b. E. lineocellata runs shorter distances and is faster in the beginning of its runs


5. Physiological bases for interspecific differences


a. E. lugubris has greater aerobic capacity (3.22 ml O2/g-h) than E. lineocellata (2.49 ml O2/g-h)

b. No differences in hind muscle mass, myoglobin concentration, citrate synthase activity, myofibril ATPase activity c. No difference in muscle contractile properties


E. Anuran: calling


1. Calling is most important reproductive behavior of a frog and has been focus of numerous studies in species recognition, sexual selection and neuroethology.

2. Primary goal of calling is energy transformation: convert metabolic energy to acoustic energy which then travels through the environment, causes a mechanical disturbance in the innerear which then results in a neural discharge that activates female reproductive behavior.

3. Very expensive, surprisingly so when first discovered, has become even more expensive as other species are studied.

4. It is also very inefficient: conversion of metabolic to acoustic energy in Physalaemus pustulosus is less than 1.5%. 98.5% of metabolic commitment to calling is wasted.

5. Most frogs make calls of wavelengths too long for their structures. Could increase radiation efficiency by making higher frequency (shorter wavelength) calls.

6. Energy not the only consideration, e.g. if Hyla crucifer increased call frequency to make louder calls:


a. heterospecifics: it would call in a less noisy channel, at least relative to two other hylids.

b. female tuning: it would not shifted away from the peak female tuning.

c. female preference: probably as a function of tuning, it would be less likely to be chosen by females.

d. transmission: it would be more intense at the source but would attenuate more rapidly in the environment.


7. Does energy limit calling strategies within a species?


a. there are calling and satellite strategies in many species

b. there is no difference between the aerobic capacity of calling and noncalling toads (Bufo americanus and Bufo woodhousii)


8. Do physiology and calling correlate among species?


a. some evidence that citrate synthase activity (an important enzyme in the Krebs cycle) is greater in trunk muscles of males than in females and also in species with higher calling effort, although samples are few and not phylogenetically controlled.
 
I would have given the ectothermic and slower metabolism response as per everyone else, are you looking for something along the lines of pythons being ambush predators who lie in wait maybe Slatey?
 
Cos they are happy just sitting around. whats wrong with being lazy?...
 
That is long answer Greg. I hope that you did not write this article your self. LOL
answer is more simple,
If snakes would be active for long period of time, they would build up lactic acid stores in the muscles. that is why they are limited.

Fangs.............. 1 point
reptile rascal.......... 6 points
Astrobeca ...................1/2 point
Fuscus ...................2 points
Morelia man ..............1/2 point
brendan_spencer ..........1/2 point
python_guy44 ..............1 point
Brodie..............1 point

Next question
which eggs take longer to hatch?
Slatey-gray snake or keelback egg.
 
I'll say it is a trick question and they take the same amount of time...
Now all bases are covered :) LOL
 
another one can be it depends on tempurature and humidity or if its a dud egg it will neva hatch
 
Well Nicole you didn't cover ALL bases. I'll say that evolution has taken a sudden turn and caused these snakes to give birth to live young and therefore neither lay eggs ;););)
 
I have a large natural history library including three dedicated books on Australian reptiles and found that ....... the slatey-grey lays eggs :-(
so I did a google and found ....... the slatey-grey lays eggs :-(
If it helps any one else , the keelback eggs take 12 to 15 weeks
 
Slatey-gray snake egg take mont longer to hatch then keelback egg in right conditions.
Well done Python guy44

Fangs.............. 1 point
reptile rascal.......... 6 points
Astrobeca ...................1/2 point
Fuscus ...................2 points
Morelia man ..............1/2 point
brendan_spencer ..........1/2 point
python_guy44 ..............2 point
Brodie..............1 point

Next question
Why sometimes male snakes mating with freshly killed female on side of the road?
 
You are right fuscus. Male is stimulated by chemical signals rather than the female's behaviours. Her smell is the go for it.

Fangs.............. 1 point
reptile rascal.......... 6 points
Astrobeca ...................1/2 point
Fuscus ...................3 points
Morelia man ..............1/2 point
brendan_spencer ..........1/2 point
python_guy44 ..............2 point
Brodie..............1 point
 
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