1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The Most Primitive Respiratory System

  1. Mar 19, 2012 #1
    1. The problem statement, all variables and given/known data

    Here is a question that I just came across while reading:

    Which of the following has the most primitive respiratory system? A. Rat B. Fish C. Toad D. Grasshopper E. Lizard
    I read thoroughly, with a view of having an answer to the question. Uptill now I have not made any success. Folks in the forum, please let's discuss it with a view of arriving at a correct answer.

    2. Relevant equations

    No equation is involved.

    3. The attempt at a solution

    The word primitive is used when one talks or make reference to something that has to do with acient period. Is use to refer to something that happened or done in early history of something.
    Now that the word (primitive) has come into this context. I don't know the type of respiratory system the first set of animal that elvoved used.
    I start by analyzing the respective ways each of the animal in question respire.
    The rat uses it's lung to respire. The fish uses it's gill for respiration in it habitat (water). The toad uses it's skin, mouth and lung to respire. The grasshopper respire by making use of it's spiracle under it (grasshopper) abodmen. The lizard uses it lung.
    From all my analysis, am choosing grasshopper as the animal that has the most primitive respiratory system based on the fact that it is the lowest in rank. What do I mean by lowest in rank? What I mean is this; all the animals mentioned are vertbrate while grasshopper is not.
    Does anyone have an idea about this?
     
  2. jcsd
  3. Mar 19, 2012 #2

    Borek

    User Avatar

    Staff: Mentor

    I don't like the question, but I would select grasshopper as well.
     
  4. Mar 21, 2012 #3
    Darwins's theory of evolution is the widely held notation that all life forms is related and has descended from a common ancestor; the birds and the bananas, the fishes and the flowers.
    Darwins's general theory presumes the development of life from non-life and stresses a purely naturalistic.
    Looking at "embroyology", one of the evidence of evolution.
    The embroyos (the earliest stage of and development of both plants and animals) of fish, reptile, birds and mammals are very similar and this are evidence that they evolved from a distant common ancestor. Embroyology shows that all have gill slits and tails in their embroyos like those of a fish.
    I can use this theory to pick fish out as the animal that has the most primitive respiratory system. How about that?
     
  5. Mar 22, 2012 #4

    Borek

    User Avatar

    Staff: Mentor

    Invertebrate trachea are definitely earlier than any respiratory system present in vertebrates.
     
  6. Mar 22, 2012 #5
    What theory or proof do you have on ground to support what you have just said?
     
  7. Mar 22, 2012 #6
    Invertebrates existed long before vertebrates came to being.
     
  8. Mar 23, 2012 #7

    Borek

    User Avatar

    Staff: Mentor

    Actually after checking different sources I am no longer sure I was correct. While arthropods are earlier than vertebrates, my understanding is that trachea similar to the one present in grasshopper didn't exist before insects colonized land (ca 400 millions years ago) - and that happened long after the first fish with gills used only for respiration entered the scene (ostracoderms - ca 510 millions years ago).

    Problem with the question is that it wants you to classify what is more primitive without defining what "primitive" means, so it leaves a lot of ambiguity.
     
  9. Mar 23, 2012 #8
    You have not made any sense yet because you are accepting something without knowing how true is it. You have to go and research and then come back with your findings.
     
  10. Mar 23, 2012 #9
    What do Borek has to say about my post in quote above?
     
  11. Mar 23, 2012 #10

    Borek

    User Avatar

    Staff: Mentor

    What tal444 wrote makes a perfect sense. We have a good fossil record proving it is true. For an outline see http://en.wikipedia.org/wiki/Timeline_of_evolution

    Hostility in your tone was noted.
     
  12. Mar 23, 2012 #11

    Borek

    User Avatar

    Staff: Mentor

    You are right about fish being the most primitive of the vertebrates listed. Question is - how to compare respiratory system with gills and respiratory system with trachea? You have to define a "primitivity" criteria before answering the question.
     
  13. Mar 23, 2012 #12
    The word "primitive" is used to refer to earliest form of something existence in link to this concept on disscusion. Is used to refer to something that happened or had earliar existed before another occured.
    Since embroyology, one of the evidence of evolution put it that the embroyos of all animal posses gill slit like those of a fish which later disappear as the embroyo grows but fish retains it own into a well developed gill system covered with opperculum and later used as organ of respiration, I put it that fish has the most primitive respiratory system.
     
  14. Mar 23, 2012 #13

    Borek

    User Avatar

    Staff: Mentor

    Define "earlier". Earlier in time, or earlier in the lineage? What if the same thing evolved more than once, like an eye, in completely different clades - which one is more primitive, the one that evolved earlier? What if the one that evolved earlier is a highly sophisticated structure, while the one that evolved later is just a light sensitive spot on the skin?

    Not all animals. Vertebrates that can trace their ancestry to fish. Grasshopper doesn't fit, as it is from completely different part of animal kingdom.
     
  15. Mar 23, 2012 #14
    Don't conclude yet. Have you taken your time to study the embryo of grasshopper?
     
  16. Mar 23, 2012 #15

    Borek

    User Avatar

    Staff: Mentor

    No. Did you?

    It works both ways - during epigenesis you can "see" evolutionary history, but you also can't see things that were not there. Last time I checked grasshopper didn't have a vertebrate ancestor with gills.
     
  17. Mar 24, 2012 #16
    Not only that, but gills and lungs are far more evolved and developed than the simple spiracles of insects. Gills are specially adapted to life in liquids. That doesn't automatically mean that it is more primitive. If we are discussing primitive as the most "simple" or least developed, than gills are certainly not the answer.
     
  18. Mar 27, 2012 #17
  19. Mar 27, 2012 #18
    Then bring a good point to back your conviction.
     
  20. Mar 27, 2012 #19
    ... I thought I made my point. Gills are adapted to living in water because lungs are useless in water, thus they have evolved. Lungs are specially adapted to life on land, because they have evolved to get the most surface area to obtain oxygen (alveoli). Insects, on the other hand, still only have relatively simple organs that allow diffusion of air in and out.
     
  21. Apr 26, 2012 #20
    It is very obvious that grasshopper has the most primitive respiratory system but according to the past question and answer booklet where I got the question from, the answer there is fish and am dragging hard to get a concrete explaination to that.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: The Most Primitive Respiratory System
Loading...