Why is it a good thing to have a body cavity?

... I'm assuming by "body cavity" you mean the mouth, ears, nose, anus?

Easiest way to explain is... it allows easier access to things that we cannot ourselves obtain through our skin, such as food, water, etc. And it also makes it easier for us to expel waste.

If we didn't have any of these body cavities, we would have to absorb all the nutrition we need via our skin, which would mostly be through endo/exocytosis. This takes too much energy, and can only support small cells/organisms. Can you imagine having to consume our daily requirement of nutrition through your skin?

Ah... yes! That make a lot of sense! Thank you so much for helping me :)

Are you sure they aren't asking about the value of the coelom?

I'm not sure... What would it be if they were asking about the value of the coelom?

We also need body cavities for our internal organs, so they will not be squashed !

While the cranial cavity houses the brain, and the vertebral or spinal cavity the spinal cord; the most crowded, I guess, would be the Abdominopelvic cavity, containing the stomach, intestines, spleen, liver, bladders, reproductive organs, even the rectum, and some others.

Also, the Thoracic cavity (pleural part for lungs, mediastinum part for the heart (pericardial cavity) and some place left for the oesophagus, trachea, etc, offers even some protection (ribs, muscles, pleura) for the incased organs.

Yeah, it's definitely a good thing to have body cavities.
:)

For more information, please see that which can be found via clicking on the following link.

Body cavity - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Pseudocoelom)

Thanks!

The primary protection for the organs in most animals is the skeleton, the ribs and other bones of the "endo"skeleton in vertebrates, the exoskeleton in arthropods. The fluid inside a coelom also provides modest resistance to squashing.

The coelom is a separation from the wall of the body, enclosed by a thin layer of membrane tissue. Inside this separate space--which is walled off from the ribs, hip bones, and muscles of the body wall-- is the intestinal tract and most of the organs of the body. Each organ is usually enclosed in its own thin, slippery membrane, so that the organs slip easily past one another inside the coelomic space when an animal (humans included) moves. After major surgery, scar tissue and "adhesions" can sometimes form, causing different organs or parts of organs to stick to one another.

We also need body cavities for our internal organs, so they will not be squashed !

While the cranial cavity houses the brain, and the vertebral or spinal cavity the spinal cord; the most crowded, I guess, would be the Abdominopelvic cavity, containing the stomach, intestines, spleen, liver, bladders, reproductive organs, even the rectum, and some others.

Also, the Thoracic cavity (pleural part for lungs, mediastinum part for the heart (pericardial cavity) and some place left for the oesophagus, trachea, etc, offers even some protection (ribs, muscles, pleura) for the incased organs.

Yeah, it's definitely a good thing to have body cavities.
:)

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Sorry, I made a mistake, by leaving one important word, "toghether", out:

We also need body cavities for our internal organs, so they will not be squashed TOGETHER !
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"Some advantages of having a true coelom...more space for complex organs and organ systems..."

Answer to 2 (http://highered.mcgraw-hill.com/sites/dl/free/0072919345/63803/30_1_2.html)

or Mader, Biology: Student Edition, eighth edition, Chapter 30.

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"The outer chest wall (thorax) is formed by 12 pairs of curved ribs, which join the sternum (breastbone) anteriorly and the thoracic vertabrae (backbone) posteriorly.

The rib cage provides bony protection for the lungs and heart."

Sherwood, Lauralee, 2005, Fundamentals of physiology: Chapter 12, p. 368, 3rd ed.
Publisher Thomson Brooks/Cole.

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My sincere thank you for each and all of you for your kind comments ! Regards: Liasdaughter