• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Discuss the Advantages and Disadvantages of being Ectothermic and Endothermic in the Vertebrates.

Extracts from this document...


Discuss the Advantages and Disadvantages of being Ectothermic and Endothermic in the Vertebrates. Introduction: Vertebrates occupy a wide variety of habitats all over the world from the freezing poles to the heat of hot desserts. In order to survive in these areas all vertebrates have adapted to regulate their body temperature, because temperature affects biochemical reactions. Organisms have been described as "bags of chemicals catalysed by enzymes". Although narrow, this emphasises that organisms are highly influenced by the rate at which chemical reactions, and hence vital life processes, occur. At low temperatures the rate of diffusion can be so low that essential functions cease and the organism dies. Below freezing point the cells may freeze and the cell structure destroyed by ice formation. Above 45oC enzymes become denatured and cease to function, again the organism dies. Therefore, if vertebrates did not regulate their body temperature they would be unable to survive outside a narrow range of habitats. There is one final point: most chemical reactions double or triple in rate for every rise of 10oC, it is therefore in an organism's interest to increase its body temperature if it wants to move faster, or react quicker, and so on. At first, the thermoregulatory modes of animals were classified according to the stability of their body temperatures, as poikilothermic or homeothermic. A poikilothermic animal has a relatively variable body temperature; a homeothermic one has a relatively constant one. These terms, while useful, have become less appropriate as our knowledge of the temperature-regulatory capacities of animals has increased, because they communicate no information about mechanism. For example, mammals have been called homeotherms and fish poikilotherms. But some mammals become torpid at night or in winter, whereas many fish live in water of constant temperature. These inconsistencies led to the development of a second level of classification - endotherms and ectotherms. All living creatures metabolise and none are a hundred percent efficient. ...read more.


Often with lizards the body temperature may only vary by a few degrees. The "activity temperature range" (ATR) is the range of body temperatures at which a species carries out its normal activities. The advantage of limiting body temperature to a narrow range during activity is that it simplifies the integration of internal processes. This is an important benefit, which can be reached by ectothermy or endothermy. In both, for example, activity within the ATR yields a maximisation of oxygen consumption and a plateau in resting oxygen consumption (i.e. resting metabolic rate does not vary with body temperature within the ATR, whereas active metabolic rate is at a maximum). This increases energy efficiency. However in endotherms the ATR is narrower and the integration of biochemical processes hence more advanced. The ectothermic way of life is not, therefore, inferior to that of endotherms, it simply represents a slower low-energy-flow approach that has its own distinct advantages. Disadvantages of Ectothermy: However there are certain costs to the ectothermic approach. Ectotherms can only regulate their body temperature if the environment is permissive of such regulation. If it is not sunny lizards cannot warm up and must remain inactive. The ectothermic metabolism allows only brief periods of high activity, because the low rate of aerobic respiration in ectotherms leads to the quick development of oxygen debt due to anaerobic respiration (often anaerobic respiration can account for 50-98% of energy production during activity). Endotherms, by contrast, are able to reach far greater speeds for longer than equivalent sized ectotherms, because they are able to aerobically respire at a much greater rate. As a result many ectotherms rely on camouflage for defence. The low rate of metabolism also restricts the possibility of attaining large size. This is why there are few ectotherms that weigh over 100 kg whereas ten percent of mammals do. The result is that ectotherms are far more reliant on their physical environment than endotherms. ...read more.


Both endothermic and some ectothermic animals (mammals and certain lizards) are known to produce fevers. Experiments have shown that fevers increase the survival rates of certain lizards, but it is not yet known why. Conclusion: Endothermy and Ectothermy represent a metabolic dichotomy affecting far more than body temperature. The implications of both modes of existence extend to such areas as activity, physiology and behaviour. Endothermy and ectothermy each have their own strengths and weaknesses, and neither is mechanistically less complex than the other. Some ectotherms are capable of regulating their body temperature around a variable fixed point, depending on the level of activity required. This has the advantage of fuel economy, because it is generally reliant on 'free' sources of energy. Endothermy and ectothermy also offer animals different advantages in different climates. In the tropics ectotherms can compete successfully with, or even outcompete, mammals both in abundance of species and in numbers of individuals because of the warm climate (that allows ectotherms to be active at night as well as day) and greater energy economy enjoyed by ectotherms. The energy they save from not maintaining an elevated body temperature can be diverted to reproduction and increasing biomass. In moderate to cold climates, however, the ectotherms are slower, are thus less competent as predators and are generally less successful than mammals. Near the poles, for example, there are no ectotherms only endotherms, because the endotherms' tissues are kept warm. The above examples have shown that there is no real example of a true endotherm or a true ectotherm, only degrees in between the two ideals. A true ectotherm is reliant totally on the physical environment for heat energy, and this environment is therefore to them primarily important. A true endotherm can maintain a constant body temperature totally independent of the physical environment, but at the cost of increased metabolism requiring extra food; to the endotherm the biological environment is primarily important. These two cases demonstrate the particular characteristics and difficulties with the two modes of life. As has been shown, neither is more advantageous than the other, overall, although one may enjoy local benefits. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Energy, Respiration & the Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Energy, Respiration & the Environment essays

  1. Marked by a teacher

    effect of temperature on the rate of respiration in yeast

    5 star(s)

    If I would measure the carbon dioxide produce by the yeast this would make me end up with more equipment such as: gas burette, tubes etc To measure the production of carbon dioxide it will take me longer to set up an apparatus there for it can be more time consuming.

  2. Marked by a teacher

    Effect of nitrate concentration on the growth of Duckweeds

    5 star(s)

    Each duckweed used was from the same pond, this increased the reliability of the results, because before staring the experiment the duckweeds all had the same nutrients and components inside the cells. As if they were all from different ponds, they may have been polluted and contained different nutrients inside them which could affect their growth rates.

  1. Marked by a teacher

    To make sure we have plenty of energy in the future, it's up to ...

    4 star(s)

    We can use the ocean's waves, we can use the ocean's high and low tides, or we can use temperature differences in the water. Let's take a look at each. Wave Energy Kinetic energy (movement) exists in the moving waves of the ocean.

  2. Marked by a teacher

    'An investigation into the ability of two strains of the yeast Saccharomyces cerevisiae to ...

    4 star(s)

    Results The following pages show the tabulated results obtained through the close following of the documented method. Manipulated data and graphical representation of the results have also been recorded. Analysis Table 5 contains the collation of all the mean volumes in cm3 of NaOH required to neutralise the 25cm3 samples of the yeast/sugar mixtures, displayed in tables 3 and 4.

  1. Field trip report Mangrove ecosystem

    However, the leaves of Aegiceras corniculatum have salt glands to secrete absorbed salts, which is not found in Kandelia candel. I suppose Aegiceras corniculatum grows better in the muddy soil which is at the lower gradient, since they seldom found on the stony ground from 0m to 30m and they are getting denser beyond 30m of the transect line (i.e.

  2. the effect of bile concentration on the activity of the enzyme lipase during the ...

    Take the pH probe rinse it with distilled water then put it into the beaker labelled pH buffer 7 5. Calibrate the pH probe so that it reads this as pH 7 this can be done by pressing the button "set as pH 7" on the pH meter 6.

  1. Describe the concept of homeostasis and the homeostatic mechanisms that regulate heart rate, breathing ...

    They filter your blood to remove excess water and waste products, which are secreted from your kidneys as urine. Temperature Body temperature is a measure of the body's ability to generate and get rid of heat. When you are too hot, the blood vessels in your skin expand (dilate)

  2. Energy absorbed by a bouncing ball.

    I think that this could be because at the smaller heights there is not much difference between the initial height and the rebound height so this will make it harder to read off an accurate value too. Again, to improve the reliability of these results I would take a few

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work