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Sharks

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grizzly
100469.  Sat Oct 07, 2006 5:17 pm Reply with quote

Sharks are amongst the longest surviving species of animal of that size having been around since the early Devonian period (around 400m years).

Most sharks have a higher oxygen demand than many other fish so they require more oxygen to pass over their gills. They can do this by moving forward continuously (called "ram ventillation) although they can stay on the same spot if they are in a current that can pass more water over their gills (although obviously to stay in the same place they effectively have to swim forward against the current). Not all sharks do this though. The blacktip reef shark and nurse sharks for example can pump water over their gills whilst they are at rest.

Sharks use an oil-filled liver (unlike other fish with a gas-filled bladder) to provide boyancy. However, they do often need to continue swimming forward to prevent sinking (many sharks employ the same principle as a wing to create "lift").

Some larger species of sharks are some of the very few fish that are able to maintain a body temperature different to the temperature of the surrounding water. A rete mirabile system is employed in these species of shark (a counter current exchange system that reduces the loss of body heat).

Sharks are amongst the few fish to give birth to live young. There are 3 main methods by which sharks can give birth:

1. Oviparity - the shark lays an egg (often called a mermaid's purse)
2. Viviparity - the shark maintains a plecental link to the developing offspring like in mamalian reproduction, giving birth to live and fully-functional young.
3. Ovoviviparity - (most sharks) offspring grow in eggs, nourished by a yolk within the oviduct where they hatch and continue to be nourished by the yolk and fluids in the oviduct. They are then born as live offspring.

Perhaps the most disturbing feature of this particular process is that the first shark that hatches will eat the other eggs in the oviduct. The pups of the grey nurse shark do what is called intrauterine cannibalism which is where they also eat the other developing embryos (immagine if a twin would happen to consume its other twin whilst still in the womb).

Sharks also exhibit some extraordinary senses. Two of these being the ability to detect the tiniest amount of blood in the water and the other being the ability to sense electrical fields.

http://en.wikipedia.org/wiki/Shark

 
Paddy Boy
100482.  Sat Oct 07, 2006 6:17 pm Reply with quote

no one cares go get a girl or look at porn, just put down the text book and DO SOMETHING!

 
suze
100483.  Sat Oct 07, 2006 6:24 pm Reply with quote

Paddy Boy, some of us do care.

The topics discussed on this forum actually are of interest to a great many of us. Some of us might happen to like porn and girls as well, but there are other places on the Internet where I'm sure you can find them if you wish.

Could I respectfully suggest that you take your own advice. If this forum bores you so much, you could always go some place else.

 
Ameena
100495.  Sat Oct 07, 2006 7:14 pm Reply with quote

He appears to be one of those people who think that the enjoyment of learning is some kind of freakish mental disorder...

 
samivel
100522.  Sun Oct 08, 2006 1:10 am Reply with quote

Paddy Boy wrote:
no one cares go get a girl or look at porn, just put down the text book and DO SOMETHING!



Oh go away.

 
grizzly
100547.  Sun Oct 08, 2006 5:06 am Reply with quote

Paddy Boy wrote:
no one cares go get a girl or look at porn, just put down the text book and DO SOMETHING!


And just think, you could have pulled down your trousers in the length of time it took for you to write that.

(sorry suze for starting the sentence with and)

 
suze
100548.  Sun Oct 08, 2006 5:10 am Reply with quote

No apology needed, and no reason why you - or anyone else - should not do so.

I know little of matters zoological, but perhaps someone who is not challenged in this way could now be so kind as to post something about sharks...

 
Hans Mof
100555.  Sun Oct 08, 2006 5:30 am Reply with quote

Only four species of shark are known to fatally attack humans: great white, bull shark, tiger, oceanic whitetip. In 2005 there were 58 recorded unprovoked attacks of which four were fatal. It is more likely to die from lightning strikes or falling coconuts.

On the other hand, man kills 200 million sharks per year (6 per second).

 
cabs
100559.  Sun Oct 08, 2006 5:37 am Reply with quote

Hans Mof wrote:
Only four species of shark are known to fatally attack humans: great white, bull shark, tiger, oceanic whitetip. In 2005 there were 58 recorded unprovoked attacks of which four were fatal. It is more likely to die from lightning strikes or falling coconuts.

On the other hand, man kills 200 million sharks per year (6 per second).


Yeah. That showed 'em. Cartilagenous swine.

Do you think sharks hide behind cushions when there are films about humans eating sharks on Shark TV?

Mouth? Mouth 2 - The Return? Mouth 3D? Mouth : The Revenge?

 
Flash
100642.  Sun Oct 08, 2006 9:38 am Reply with quote

Hans Mof wrote:
It is more likely to die from ... falling coconuts.

Do you have the stats on that, Hans? It's an idea we have wondered about in the past.

 
Flash
100645.  Sun Oct 08, 2006 9:40 am Reply with quote

Quote:
In 1983, two researchers at the Massachusetts Institute of Technology published a study showing that shark cartilage contains a substance that significantly inhibits the development of blood vessels that nourish solid tumors, thereby limiting tumor growth.

Working independently, medical researchers at Harvard University Medical School found that if one could inhibit angiogenesis--the development of a new blood network--one could prevent the development of tumor-based cancer and metastasis.

In his book, SHARKS DON'T GET CANCER--HOW SHARK CARTILAGE COULD SAVE YOUR LIFE, Dr. I. William Lane ties together these two important findings regarding shark cartilage and angiogenesis. Dr. Lane also recounts his own involvement in the search for a truly effective treatment of tumor-based cancer and examines the work of researchers who have conducted studies that indicate that shark cartilage can be effective in reducing cancer related tumors and also reduce the inflammation and pain associated with other conditions, such as arthritis, psoriasis and enteritis.


http://www.realife.com/angioinhibitor.html

 
Flash
100649.  Sun Oct 08, 2006 9:42 am Reply with quote

Shark liver oil is an ingredient of the suppository Preparation H:
http://www.preparationh.co.uk/products/suppositories.htm

 
grizzly
100661.  Sun Oct 08, 2006 9:50 am Reply with quote

Flash wrote:
Hans Mof wrote:
It is more likely to die from ... falling coconuts.

Do you have the stats on that, Hans? It's an idea we have wondered about in the past.


I thought it had made it onto the show before in some form.

 
eggshaped
100668.  Sun Oct 08, 2006 9:53 am Reply with quote

Quote:
SHARKS DON'T GET CANCER--HOW SHARK CARTILAGE COULD SAVE YOUR LIFE


um...

Quote:
Researchers at George Washington University Medical Center in Washington, D.C., reported they have documented more than 40 cancerous and benign tumors in sharks and their close marine relatives, including skates and rays. Three of the tumors were chondromas tumors of cartilage in sharks.


http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Sharks_Get_Cancer.asp


Last edited by eggshaped on Sun Oct 08, 2006 9:54 am; edited 1 time in total

 
Flash
100669.  Sun Oct 08, 2006 9:54 am Reply with quote

Quote:
I thought it had made it onto the show before in some form.


Yes, but we put it on the show before we realised we didn't know the answer. Very edgy stuff.

Egg - VG

 

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